Midterm

Prions

- Creutzfeldt-Jakob disease (CJD) is a rare and devastating disorder in which the patient becomes demented and ultimately dies, and the brain appears spongy on autopsy because many brain cells have died. - However, no virus or bacteria has been found responsible for causing the condition. In 1997, Stanley Prusiner, a scientist at the University of California Medical School in San Francisco, won the Nobel Prize for his controversial theory that this type of disease is caused by particles called prions, which contain protein but no nucleic acid and thus no traditional genetic material. In 1996, a paper appeared in a British medical journal reporting that ten persons in the United Kingdom younger than 45 years of age had been diagnosed with a CJD-like condition, an unusually high incidence in a group much younger than those usually struck by the disease. 88 The authors suggested a link with an epidemic of bovine spongiform encephalopathy (BSE), known as "mad cow disease," which had killed over 160,000 cattle in Britain over the previous decade. - A flurry of alarm and a European ban on British beef led the British government in 1996 to order the mass slaughter of all at-risk cattle to prevent the possibility of human exposure to infected beef. - The evidence is strong that consumption of contaminated beef is the cause of new variant CJD (vCJD). - Americans have little chance of being exposed to BSE in the United States. Regulations on cattle feed have been tightened, and certain ruminant parts are prohibited from entering the food supply. - Restrictions have been introduced that prohibit importation of live ruminants, such as cattle, sheep, and goats, except from Canada, which also implemented stricter feed regulations. Other prion diseases have been identified in humans and animals. Two of them, Gerstmann-Strausler-Schenk syndrome and fatal familial insomnia, are extremely rare genetic diseases. The third, kuru, was endemic in certain tribes in Papua New Guinea, where it was recognized and studied in the mid-20th century. The only one of these diseases that could potentially threaten human health in the United States is chronic wasting disease (CWD), which affects North American deer, elk and moose.

Cohort Studies and Relative Risk

Cohort Studies: linking exposures by observation and without actively involving in the lives of human subjects. (prospective study) Large number of people interviewed about health conditions during the beginning of the study. Observed over a period of time and then interviewed again to see how many developed the diseases and how many did not? Whether the exposed are likely to develop the disease as compared to those who are not exposed Relative Risk: Strength of an association between the exposure and the occurrence of the disease Ratio of the incidence rate per persons exposed to a disease factor to the incidence rate per persons in the unexposed group Relative Risk >1.0 indicated increased risk from exposure Relative Risk<1.0 indicates decreased risk Prospective study: means moving forward, find a cohort so group of people who lives in a specific city, then you collect all of their social demographic information such as where they live, age, whether they are married or not, gender, where do they work, what are their lifestyles Follow them up every 1 year, once in 6 months, once in 2 years, once in 3 years, and follow them up with each time asking the same set of questions and trying to see how or what are the different types of diseases developing or what happens to their life since each have a specific lifestyle (SO IN THIS STUDY YOU ARE ONLY DOING OBSERVATION) Cohort study: Since such experiments are not possible for most hypotheses that epidemiologists want to test, methods have been devised by which investigators can link exposures to results by observation alone, without actively intervening in the lives of the study subjects. Large group of people in cohort: all healthy at the time the study begins— are questioned concerning their exposures. They are then observed over a period of time to see whether those who were exposed to the factor being studied are more likely to develop the disease than those who were not. This approach is similar to performing an experiment, except that the people themselves have chosen whether they belong to the "exposed" group or the control group. Another well-known cohort study, still under way, is the Nurses' Health Study, which since 1976 has been following some 120,000 married female nurses, looking for factors that may be related to the development of breast cancer and other diseases. The participating nurses have been sent questionnaires every two years, asking about their diet, drinking and smoking habits, and use of drugs, including oral contraceptives. We calculate relative risk from a cohort study (asking how many people within the cohort was exposed and how many people actually developed the disease) The measure of the strength of association obtained by cohort studies and intervention studies is the relative risk, which is the ratio of the incidence rate for persons exposed to the factor to the incidence rate for persons in the unexposed group. A relative risk of 1.0 means that there is no association between the exposure and the disease. A value greater than 1.0 indicates an increased risk from exposure, while a value less than 1.0 indicates a decreased risk. Incidence rate per persons exposed to a disease: how many new cases have happened among people who are exposed to the disease Incidence rate per person in the unexposed group: among those who were not exposed but still developed the disease For example people who are smoking versus non smoking so how many people who were smoking developed the disease/ and how many people were non smokers but still developed the disease

Which of the following statements is true?

Costs of public health measures are easier to calculate than benefits.

Influenza-like illness

Cough and fever and cannot tell they have pneumonia, then it is an influenza like illness ILI could have a different type of virus such as respiratory viruses, bacteria, and other pathogens (track it because it is based on clinical symptoms)

Death Rate

Death Rate: number of deaths per 1000 people (500 per year is a low number in a city of 100,000, while it is high for a city of 50,000) Birth Rate: Number of live births per 1000 people It is important to know the population of that city/ area. Fertility Rate: Number of live births per 1000 women aged 15 to 44 years Infant Mortality Rate: Number of infants that die before their first birthday in a year, divided by number of live births that year Maternal Mortality Rate: number of deaths among women associated with pregnancy and delivery in a year, divided by the number of live births in that year. Infant mortality rate: not looking at all the children, only looking at the live births for that particular year and out of that there are 1,000 life births, out of 1000 children how many of them actually died before their first birthday For some purposes, the numbers can be made still more useful by converting crude rates into adjusted rates. Death rates are often adjusted for the age of the population. The adjustment uses a statistical calculation to make the populations being examined equivalent to one another. For example, the crude mortality rate in Florida is much higher than the crude mortality rate in Alaska. There is no cause for alarm in Florida, however. Since the average age of the Floridians is significantly higher than the average age of Alaskans— in fact many residents of other states retire to Florida and die there, while people who move to Alaska are likely to be young— it is to be expected that a higher percentage of Floridians die each year. After adjusting the mortality rate to what it would be if the average ages of the two populations were the same, the age-adjusted mortality rate for Alaska is higher than that in Florida, as seen in (Table 7-1). Rates may also be adjusted for other factors relevant to health, such as gender, race, ethnicity, and so forth. Rates are also calculated on a group-specific basis. Researchers may calculate rates for males alone or females alone, blacks, whites, Hispanics, members of other racial or ethnic groups, and people in defined age groups. This kind of data informs us, for example, that males have higher mortality rates than females in the same age group, and that blacks have higher mortality rates than whites of the same sex and age. It is common to break down death rates from various causes by age group, revealing that different age groups are more likely to die of different causes. For example, death rates from cancer, stroke, and heart disease increase steadily with age, except for a small peak in deaths of infants because of congenital heart defects. Another calculated concept that is sometimes used as a measure of premature mortality is years of potential life lost (YPLL). It gives greater weight to deaths of young people, appropriate to the priorities of public health, which has the goal not of eliminating death entirely but of enabling people to live out their natural lifespan with a minimum of illness and disability. Calculation of YPLL arbitrarily chooses 75 as the age before which a death is considered premature (age 65 was used before 1996). As an example, the death of a person 15 to 24 years of age counts as 55.5 YPLL before age 75. Unintentional injuries rank relatively high in YPLL because they are likely to kill young people, who have more years to lose.

Herd Immunity- the concept

Germ may affect girl If she hangs out and spreads it to others, to her dad, grandmother...etc.. What if you vaccinated some people (pentagon represents vaccination) so she cant affect these people anymore and even if people get sick (hard time spreading it to someone else) If you vaccinate or some people, most people are protected

Heart Disease

Heart disease has been the leading cause of death in the United States for both men and women. After World War II, one in every five men was affected with heart disease before the age of 60 In 1948, an epidemiologic study was launched in Framingham, Massachusetts, to investigate factors that might be causing the problem. It was the first major epidemiologic study of a chronic disease. The study identified three major risk factors: high blood pressure, high blood cholesterol, and smoking Weight gain and lack of exercise were found to be associated with increased blood pressure and cholesterol values and with an increased risk of heart disease. The Framingham findings had a major impact on the course of the heart disease epidemic. Publicity on the information gained by the study, confirmed and supported by other studies, persuaded some people to change their behavior and formed the basis of public health programs to encourage others to do the same The Framingham Study itself found in 1970 that the death rateover the previous 10 years had declined by 60 percent since 1950. This improvement was associated with a decline in risk factors: In 1970, blood cholesterol levels were lower; blood pressure was lower; and smoking was less common. Meanwhile, the Framingham Study has continued and expanded, and much more has been learned. For example, a smoker's risk of heart disease rapidly drops back to that of nonsmokers soon after the smoker quits; but low-tar, low-nicotine cigarettes are no better than the old-fashioned kind in their effects on risk of heart disease. Various forms of cholesterol have been identified, including high-density lipoprotein (HDL) cholesterol— the "good" kind that is protective— and low-density lipoprotein (LDL) cholesterol— the "bad" kind. Drinking alcohol in moderation has been found to increase HDL cholesterol and to protect against heart disease. Exercise also raises HDL levels. The scope of the Framingham Study has expanded: In 1978, the subjects began to be given neurological examinations in addition to tests for cardiac risk factors. The investigators were watching for the development of Alzheimer's disease in the aging study population, hoping that they would be able to detect risk factors for this increasingly common and tragic condition. An offshoot of the original study, the Framingham Offspring Study, was created in 1971; it included about 5000 children of the original participants and their spouses. Investigators use comparisons of risk factors within families and across generations, hoping to sort out the roles of genetics and environment in heart disease and other common disorders. The younger study population is being tested with more advanced medical technologies and more sophisticated blood tests, including genetic tests. In 1994, a more diverse sampling of Framingham residents, called the Omni Cohort, was added. Another expansion to form the Third Generation Study, which enrolled grandchildren of the study's original participants, was added in 2002 and a Second Generation Omni Cohort, as well as a New Offspring Spouse Cohort, in 2003. The diseases now being studied include diabetes, lung disorders, osteoporosis, arthritis, eye diseases, and hearing disorders

Steps Summary

Multi pronged approach Not enough to 'train' and 'educate' people on healthy life style Easy & affordable access to an environment that promotes healthy life style

Which of the following is NOT part the "who" question of disease distribution:

Neighborhood of residence

Cohort study characteristics

Often require long periods of follow-up • Good for diseases with short duration between exposure and outcome exposure and outcome • Pregnancy, viral illness • Good for rare exposures

Selection of controls examples

Testing hypothesis that tuberculosis protected against cancer • From autopsies identify 816 cases of cancer and 816 controls • Determine how many of each group had tuberculosis

Prevention of Chronic Diseases

The STEPS program This program funds 40 selected US communities to address 6 leading causes of death and disability and rising healthcare costs 2003-2006 and later extended till 2010 Jointly by CDC and DHS Focus on tobacco use, poor nutrition and physical activity Increase awareness and educate participants about chronic disease prevention Two phases: 1) Created education and awareness 2) Providing venues or opportunities to translate the knowledge on health behaviors into practice

Ecological Study example from graph

Trends in large populations Death rates due to coronary heart disease due to alcohol consumption Death rates increased as Per capita alcohol decreased

Distribution of disease

Who - sex age occupation race sex, age, occupation, race • When - season, year (long-term trends), elapsed time since an exposure (epidemic curve) time since an exposure (epidemic curve) • Where - neighborhood (e.g. clusters), latitude (climate) urban vs rural national variations (climate), urban vs. rural, national variations

Definitions of shift with influenza

Why do some seasons are not so bad as others? Because each year, the flu virus changes a bit Antigenic drift: small changes in the RNA sequence such as a nucleotide or substitutions Antigenic shift: more of a broad illness, people do not expect (more dramatic changes in the antigen structure of the virus such as H2N2 and H3N2)

Disease investigation

Who? Characteristics of disease victims such as age, sex, race and economic status When? Looks for trends in disease frequency over time: whether the incidence is increasing? Decreasing? Or remaining same? Epidemic curves gives us an understanding of who got the disease when? Who was exposed when? Where? Comparison of disease frequency in different counties, states, countries or other geographical regions. This helps in generating a hypothesis about cause of the disease. All the above explain distribution of disease which gives clues on determinants of disease The distribution of disease is comprised of the answers to the who, when, and where questions. The who question characterizes the disease victims by such factors as age, sex, race, and economic status. The who question characterizes the disease victims by such factors as age, sex, race, and economic status. For example, the incidences of cancer and heart disease are greater in older people; measles and chicken pox occur more often in the young. Old women and young men are more likely to suffer broken bones than old men and young women. During the early months of the AIDS epidemic, the answer to the who question was gay men and intravenous drug abusers. When question looks for trends in disease frequency over time, so is the disease decreasing, increasing, or remaining the same over a period of time?? Posing another kind of when question, epidemiologists look for seasonal variations in incidence. The incidence of respiratory infections is always higher in the winter. The when question is crucial in tracking an outbreak of infectious diseases such as hepatitis and legionellosis. Epidemiologists construct epidemic curves by plotting the number of cases identified over a period of time The where question looks at comparisons of disease frequency in different countries, states, counties, or other geographical divisions. It may also look at comparisons between urban and rural populations. The relevance of the who and when questions is clearly illustrated in the evidence that smoking is a determinant of lung cancer. Men began smoking cigarettes early in the 20th century, and lung cancer rates began rising 20 years later. Women did not begin smoking in large numbers until the 1940s and 1950s. Lung cancer rates for women did not begin to rise sharply until the 1960s. The hypothesis that fluoride protects against tooth decay arose from the observation that dental cavities were less common in children who lived in parts of the country that had high concentrations of fluoride in the water. Statistics on causes of death in different countries can be very suggestive in generating hypotheses about the causes of disease. The wide international variation in death rates from heart disease has been interpreted in a variety of ways, including that diet is a factor and that the pressures of urban life have a negative effect on health. Distribution of disease gives us clues on determinants of disease Some world examples of determinants: Cancer of the colon and rectum was much more common in industrialized countries than in developing countries, which led to the hypothesis that the difference is due to differences in diet: Americans eat meals rich in fat, meat, and dairy products, while diets in China are traditionally high in fiber, cereals, and vegetables. Evidence that environmental factors rather than genetics are to blame comes from studies of people who move from a low-rate country to a high-rate country. They tend to develop higher rates of the disease as they acquire the habits of the host country. In Japan, the rates of colorectal cancer more than doubled between the 1950s and the 1990s as Japanese adopted more Western-style diets. However, as more is learned about other risk factors for breast cancer, such as hormonal and reproductive history, it has become clear that diet is not the whole story. The incidence of breast cancer in Japan is less than half the rate in the United States. Rates of stomach cancer are much higher in China and Japan than in the United States, evidence that different dietary factors may be involved; diets high in smoked foods, salted meat or fish, and pickled vegetables increase the risk of stomach cancer. However Helicobacter pylori, the bacteria that cause ulcers, also play an important role in causing stomach cancer.

Clinical symptoms of influenza

abrupt onset of fever, myalgia, and malaise cough and sore throat patients with uncomplicated influenza improve over 2-5 days the major complication of influenza is pneumonia Over a few hours can go from well to completely whipped out Myalgia: muscle aches Malaise: general feeling of weakness and tiredness, so people would rather lay in bed Pneumonia: can be caused by flu, after the lung has been attacked, can be susceptible to other times of pneumonia like bacterial pneumonia and that is very bad one

Options for public health control

annual vaccination Chemoprophylaxis: prevent people from getting it in first place nonpharmacologic: improved handwashing and improved respiratory hygiene community-level strategies such as closing schools, avoiding mass gatherings Vaccinations and herd immunity They did not vaccinate kid for flu because kid was allergic to eggs and they also seemed to be allergic to flu vaccine Kid may be protected if other kids are vaccinated because they will not get flu, will protect unvaccinated from getting flu immunity that occurs when the vaccination of the portion of the population (herd) provides protection to unvaccinated individuals

Which of the following is not part of the chain of infection?

immunization

Influenza transmission

infection can be transmitted through coughing, sneezing, and talking via large-particle droplets Cough hands and shake someone else's hand: droplets can spread virus People will be infected a little bit before sheading and day 2 is peak shedding before exposure Need to be very close to people

Biomedical sciences role in public health does not include:

surgery for breast cancer

Blinding is not generally used in community trial.

true

Types of infectious pathogens

virus bacteria prions helminths parasites Virus: single cell without a cell wall Bacteria: cell wall and single cell Prions: contagious, pieces of DNA material that are associated with disease and transmitted and cause bad health issues Helminths: worms, flukes, causes of health issues in children, anemia, low blood count Parasites: such as the parasite that causes malaria and parasites associated with opportunistic infections and HIV

Determinants of disease

• Why is distribution as it is? Why is distribution as it is? • Can make inferences from distribution • Risk factors

Which of the following is not true of intervention studies?

Subjects choose for themselves what their exposure is

Study Design 1st step

Identify exposure and outcome of interest Identify exposure and outcome of interest • Exposure: the variable hypothesized to be related to the outcome the outcome • Outcome: any disease state, condition, or other variable examined as the end point • Formulate your research question and hypothesis

Incubation Period

Incubation Period: defined as the interval from receipt of infection to the time of onset of clinical illness Time needed for the organism to multiply and reach a critical mass that could result in infection Dose of infectious agent received

Understanding cancer, therefore, requires understanding normal cell function, so that it is possible to recognize what goes wrong in a cancer cell. In general, a normal cell turns cancerous through a mutation in the genetic material, DNA— usually a mutation in one of the genes that regulate cell growth and differentiation.

- When the cell divides, the mutation is transmitted to the daughter cells, which, because of the disruption in control caused by the mutation, tend to divide more rapidly than normal. As the cells continue to divide abnormally, errors tend to occur as the DNA is copied, leading to additional mutations and more abnormalities in the cells that are becoming a tumor. Other changes that may accompany the formation of a tumor are the stimulation of the growth of blood vessels that feed the tumor and the tendency to metastasize— a process by which cancer cells detach from the main tumor and spread to distant parts of the body.

Which of the following statements about infectious diseases is NOT true?

All are not true- these are all true Most infectious diseases can be cured by antibiotics Infectious diseases are the leading cause of death in the United States. Infectious diseases cannot be transmitted from animals to human

What are some of the characteristics of 'vulnerable subjects' in while obtaining informed consent for research?

All of the above is the answer Powerdifference between researcher and participant Cognitive and communicative difficulties of participants You Answered Socially and economically disadvantaged population

Influenza infections

Annual epidemics of seasonal influenza occur typically during late fall through early spring FLU in southern hemisphere is how we base our next season, antibiotic vaccine recommendations rates of infection are higher among children rates of serious illness and death are highest among people aged less than 65 years of age and children less than 2 years old and medical conditions such as Complications: chronic respiratory diseases, diabetes, kidney disease, liver disease

Three core functions of public health

Assessment • Constitutes the diagnostic function in which a public health agency collects, assembles, analyzes and makes available information on health of population Policy Development • Involves the use of scientific knowledge to develop strategic approach to improving community's health Assurance • Involves assuring public that the services needed for protection of public health, including environmental, educational and medical services, in the community are available and accessible to everyone

The Uncertainty of science

But the answers are not as definitive as people want them to be. Science has shown that the human immunodeficiency virus (HIV) causes AIDS. But that does not mean that a woman will definitely contract AIDS from having sex with an HIV-positive man. Her chance of becoming infected with the virus from one act of unprotected intercourse is about one in 1000. However, a woman who chooses the lumpectomy still has a 10 percent chance of cancer recurrence. 2 Both the woman who had unprotected intercourse and the woman who chose the lumpectomy would dearly like to believe that they will be one of those in the majority of cases who will have a positive outcome, but science cannot promise them that. It can only say, statistically, that if 1000 women like her have unprotected sex with an HIV-positive man, 999 probably will fare well while one will not, and if 100 women with early breast cancer have a lumpectomy with radiation, 90 probably will be cancer-free after 12 years while 10 will have a recurrence. In 1995, the New England Journal of Medicine published a report that the Nurses' Health Study (a cohort study), which had monitored 122,000 nurses for 14 years, found a 30 to 70 percent increased risk of breast cancer in women who had taken hormone replacement therapy after menopause. 3 One month later, the Journal of the American Medical Association published the results of a case-control study that found no increased risk from the hormones. Some 500 women who had newly diagnosed breast cancer were no more likely to have taken postmenopausal hormones than a control group of 500 healthy women. In The New York Times article reporting on the studies, each researcher is quoted suggesting possible flaws in the other study. There was little comfort in these results for women seeking certainty on whether the therapy would improve their health. According to one view, postmenopausal estrogen was clearly worth the possible risk of cancer because it appeared to decrease a woman's risk of heart disease and osteoporosis. In the opposing argument, women could achieve similar benefits without the possible risk through exercise, avoiding smoking, eating a low-fat diet, maintaining a normal weight, and taking aspirin. Now a clinical trial has contradicted some of the findings of each of these studies; hormone replacement therapy has been found to increase cancer risk and not to benefit the heart. People sometimes demand certainty even when science cannot provide it, as occurred in 1997 over the issue of whether women ages 40 through 49 should be screened for breast cancer using mammography. Studies had shown that routinely testing women aged 50 and over with the breast x-rays could reduce breast cancer mortality in the population. However, studies done on younger women had not demonstrated a life-saving benefit overall for this group. Routine screening of these women increases their radiation exposure, perhaps raising their risk of cancer. It also yields many false alarms, leading to unnecessary medical testing, and major expense. When Dr. Richard Klausner, the director of the National Cancer Institute (NCI), called together a panel of experts in early 1997 to advise him on the issue, the panel concluded that, for younger women, the benefit did not justify the risks and costs, and recommended that each woman make the decision in consultation with her doctor, considering her own particular medical and family history. The public and political response was heated: After a barrage of media publicity, the Senate voted 98 to 0 to endorse a nonbinding resolution that the NCI should recommend mammography for women in their 40s. A letter signed by 39 congresswomen stated that, "without definitive guidelines, the lives of too many women are at risk to permit further delay," assuming that screening could save lives despite the lack of evidence. In the end, director Klausner, with the support of President Clinton and Secretary of Health and Human Services Donna Shalala, recommended that women in their forties should be screened. However, because the incidence of breast cancer is lower in women in their 40s, and the effectiveness of mammography is also lower in the denser breasts of the younger women, the benefit of screening is less for them. In a review of the evidence published in 2007, the conclusion seems to echo the NCI's original recommendation that individual women, in consultation with their doctor, should decide whether to be screened. The authors suggest that, "a woman 40 to 49 years old who had a lower-than-average risk for breast cancer and higher-than-average concerns about false-positive results might reasonably delay screening. Measuring risks and benefits accurately enough to identify these women remains a challenge." Remarkably, the whole political uproar was repeated in 2009, when an independent panel of experts, appointed by the Department of Health and Human Services, issued a recommendation that routine breast cancer screening begin at age 50, not 40. Because the recommendation was published in the midst of the public debate over health care reform, conservative politicians cried "rationing." As science reporter Gina Kolata pointed out in a New York Times article, the dispute gives many people "a sense of déjà vu." 10 The data hadn't changed much since the earlier debate, except that new evidence was published in 2008 suggesting that some invasive breast cancers may spontaneously regress, supporting the argument that screening may lead to unnecessary treatment

Limitations of Observational studies

Difficult to avoid or assess causal relationships • Because treatment or exposure is not assigned, it occurs by choice or chance • Possible that exposed and unexposed differ in important ways other than the exposure

Experimental study design

Experimental design sits at the top of the level and produce most valid results but come at a high cost

Constructing a Cohort

Exposed and unexposed should be: • From the same source population • As similar as possible (other than exposure status) • Free of outcome at the beginning - we are measuring incidence disease/events

Which of the following studies has given the most valid result:

Exposure to aspirin during a viral infection causes Reye's syndrome (odds ratio 42.7)

Which of the following explains external validity?

Extent to which the results can be applied to people not in the study Generalizability Representativeness of the population from which the sample was drawn All of the above is the answer

Clinical symptoms of influenza includes a delayed onset of fever, headache, myalgia and malaise

FALSE

Public health law is determined by all of the following bodies, including the legislature, the executive, the courts, and nongovernmental agencies.

FALSE

Case Series Example

Five chest x Five chest x-rays of young men in a San Francisco rays of young men in a San Francisco hospital that showed an unusual type of pneumonia, Pneumocystis Carinii Pneumonia • First description of Gay related immunodeficiency later remained HIV that causes AIDS • The young men also had sex with men in their history

Constructing a Case Control Study

Have the disease cases: either were exposed or not exposed do not have the disease controls: were exposed or were not exposed assess whether or not the participant has the disease first Cases are those with the disease or outcome of interest Controls should be people from the same population as cases who are at risk of developing the outcome but do not currently have it • Interview both cases and controls on exposure status So exposure histories of controls are compared to one another, essential feature is comparison of cases and controls and exposure histories

Types of epidemic study

Intervention studies: used to test a new treatment for a disease One group is exposed to the treatment and the other group (control group) is not exposed Enough justification that treatment is somewhat effective and will not harm any people (eg: Fluoridation of drinking water) Placebo: Control group may receive a placebo (an inactive substance similar in appearance to drug or vaccine given to the intervention group Randomized double-blind trials: participants are assigned randomly to the control or the intervention group; both the participant as well as the treating doctor is blind to whether the participant is receiving a drug or a placebo Intervention studies: Look whether to see the intervention we gave to the treatment group has been successful or not They are usually done to test a new treatment for a disease, such as a chemotherapy drug for cancer, or a preventive measure, such as a vaccine. In a clinical trial, one group is exposed to the intervention, while a control group is not exposed. The control group may be given a placebo— an inactive substance similar in appearance to the drug or vaccine being tested. When a treatment for a disease is already known to exist, trials may compare the new treatment with the existing treatment. The purpose of the placebo is to prevent subjects from knowing whether they are receiving the intervention. Many trials over the years have found that up to a third of patients respond to a placebo as if it were the intervention, reporting that they feel better or that they suffered side effects- this is the placebo effect The drug being tested must show a higher response rate than the placebo if it is to be considered effective. Fluoridation of drinking water: please read the textbook to have a better understanding, looked at two cities and did a dental check up for the children in the schools In NY, added fluoride to the drinking water in one city and not the other and in 10 years they did a check up on the study More people had to ticket the city where the water was not fluoride, did not observe the side effects of adding fluoride on people therefore led to the policy that fluoride is being added to drinking supply in all cities and it prevents children from getting tooth decay The most convincing clinical trials are conducted in a randomized, double-blind manner. Randomized means that each subject is assigned to the treatment group or the control group at random. This helps to equalize the groups with respect to unknown and known factors that might affect the results. Double-blind means that both the patient and the doctor are blind as to whether the patient is receiving the drug or a placebo. One reason that the doctor should also be blinded is that studies have shown patients to respond more favorably to a treatment that the doctor believes in. Another reason is to prevent the possibility that doctors might interpret the patient's condition differently if they know how the patient is being treated. A classic example of a randomized, double-blind clinical trial of a preventive intervention is the field trial of the polio vaccine in 1954. Polio, then a greatly dreaded disease in the United States, killed and paralyzed children and adults. Before the vaccine could be approved for widespread use, however, it had to be tested in a clinical trial to determine if it really could protect a large number of people against the disease. In 1954, some 400,000 school children in 11 states were given the Salk vaccine or a "dummy" vaccine (the placebo); they were then tracked through the end of the year to see whether they became ill with polio. The incidence of polio among the children who had received the vaccine turned out to be less than half that of those given the placebo vaccine. This result demonstrated that polio immunization could reduce the incidence of disease; in fact, the use of the vaccine Another randomized controlled trial of a preventive intervention is the Physicians' Health Study, in which 22,000 American physicians participated. Two hypotheses were being tested: whether aspirin reduced mortality from heart disease and whether beta carotene decreased the incidence of cancer. The physicians were randomly divided into four groups: those who took aspirin and beta carotene, those who were given one or the other and a placebo, and those who were given placebos only. The trial began in 1983 and was scheduled to run until 1995. The aspirin part of the trial was halted in 1988, however, because it was clear by that time that the physicians taking aspirin had a much-reduced risk of suffering a heart attack. 11 They were only 56 percent as likely to have a heart attack as the group taking the placebo. The beta carotene part of the trial, which continued until 1995, found no significant difference in the incidence of cancer between the group receiving the beta carotene and the placebo group. The Kingston- Newburgh study of fluoride for the prevention of tooth decay was another form of intervention. The children of Newburgh were found to have approximately half as many decayed, missing, or filled teeth as the children of Kingston had. No adverse health effects were found in the Newburgh children. This evidence was strongly supportive of the value of fluoridation in preventing tooth decay.

John Snows pumps

John Snow created a table where he looked at all the houses and water supplies that lived in the area where the disease had occurred Found that all the people in the area had two sources of water supply One is the Southwark and Vasshall Co and other one was by the Lambeth Company Each company had different sources for their water supply and when he enumerated the people who got effected by cholera, looked at each company to see where they were getting their water source He found that if people get their water supply from one company it is more effective and caused more debt as compared to others who got their water supply from pipelines supplied by another company

Which of the following measures would NOT be considered primarily an attempt to legislate morality?

Laws against drinking and driving

what types of flu vaccine are available?

Live virus works better (nasal) Fluzone intradermal: get away from needles, new virus this year killed attenuated virus (intramuscular) Trivalent: this year we cover two types of influenza A and one for influenza B (Covers 3 different influenza variants each year)

Which of the following diseases is transmitted by a vector:

Malaria

Other Chronic Diseases:

Mental illness is a major cause of disability in this country, and yet very little is known about its causes and prevention. - Alzheimer's disease and other forms of dementia in older people cause anguish to their families and force affected people into nursing homes at a tremendous cost to society. - NIH sources are supporting a great deal of research on understanding genetic and other factors that affect people's risk of developing dementia as they age, but not much is known yet on how people can protect themselves. Arthritis, while not a major killer, can severely impact the quality of life for many older people, causing great pain and suffering in their last years.

Public health law is determined by all of the following bodies except:

Nongovernmental agencies

Analytic study design

Observational studies: No intervention implemented Observational studies: No intervention implemented, no randomization • Ecologic • Cross-sectional • Case-control • Cohort • Experimental (or intervention) studies: Test an intervention, groups are randomized to eliminate differences between study groups • Randomized clinical trials • Group randomized trials

P-value

P value: if you toss a coin and repeat the same test a hundred times, you will get the same results 95 times Probability: Scientists quantify uncertainty by measuring probabilities. Since all events, including all experimental results, can be influenced by chance, probabilities are used to describe the variety and frequency of past outcomes under similar conditions as a way of predicting what should happen in the future. Aristotle said that, "the probable is what usually happens." Statisticians know that the improbable happens more often than most people think. One concept scientists use to express the degree of probability or improbability of a certain result in an experiment is the p value. The p value expresses the probability that the observed result could have occurred by chance alone. A p value of 0.05 means that if an experiment were repeated 100 times, the same answer would result 95 of those times, while 5 times would yield a different answer. If a person tosses a coin 5 times in a row, it is improbable that it will come up the same— heads or tails— every time. The probability of that occurrence is 1 chance in 16, or 0.0625 (p = 0.0625). Thus a p value of 0.05 says that the probability that an experimental result occurred by chance alone is less than the probability of tossing 5 heads or 5 tails in a row. A p value of 0.05 or less has been arbitrarily taken as the criterion for a result to be considered statistically significant. Another way to express the degree of certainty of an experimental result is by calculating a confidence interval. This is a range of values within which the true result probably falls. The narrower the confidence interval, the lower the likelihood of random error. Confidence intervals are often expressed as margins of error, as in political polling, when a politician's support might be estimated at 50 percent plus or minus 3 percent. The confidence interval would be 47 percent to 53 percent. If a p value of 0.05 is taken to imply statistical significance, 5 out of every 100 ineffective treatments would appear to be beneficial, errors caused purely by chance. 11 Thus, large numbers of cancer treatments could be in clinical use that are actually not effective. Other reasons that a low-p-value study could lead to an erroneous conclusion could be bias or confounding, which are systematic errors. The results of the study that linked coffee drinking with pancreatic cancer were statistically significant with a p value of 0.001.12 The conclusion is thought to be wrong not because of random error but because the cancer was caused by smoking rather than coffee drinking. The fact that the probable is not always what happens leads to the Law of Small Probabilities. 11 The most improbable things are bound to happen occasionally, like throwing heads 5 times in a row, or even— very rarely— 99 times. This means, for example, that a few people with apparently fatal illnesses will inexplicably recover. They may be convinced that their recovery was caused by something they did, giving rise— if their story is publicized— to a new vogue in quack therapies. But because their recovery was merely a random deviation from the probable, other patients will not get the same benefit. Another consequence of the Law of Small Probabilities is the phenomenon of cancer clusters. Every now and then a community will discover that it is the site of an unusual concentration of some kind of cancer, such as childhood leukemia, and everyone will be highly alarmed. Is there a carcinogen in the air or the drinking water that is causing the problem? Could the cause be electromagnetic fields, which residents blamed for the cluster of six cases of childhood cancer between 1981 and 1988 among the pupils of an elementary school in Montecito, California? In the case of the electromagnetic fields, it could not be proven that they were not responsible for the cluster, but as more studies are done the evidence is still ambiguous. Most such clusters are due to statistical variation, like an unusual run of tails in a coin toss. Such an explanation tends to be unsatisfactory to community residents, who may accuse the government of a cover-up; but after the investigation the number of new cases usually returns to more or less normal levels, and the sense of alarm subsides. If a cluster is very large, it is likely not to be a random variation— just as in coin tossing, 50 heads in a row is a much less likely outcome than five heads unless there is somethingwrong with the coin. A large number of cases is said to confer power on a study. Power is the probability of finding an effect if there is, in fact, an effect. Thus, an epidemiologic study that includes large numbers of subjects is more powerful than a small study, and the results are more likely to be valid, although systematic errors due to bias or confounding can be present in even the largest studies. In designing studies of any kind, statisticians can calculate the size of the study population necessary to find an effect of a certain size if it exists. Studies with low power are likely to produce false-negative results (i.e., to find no effect when there actually is one). False-positive results occur when the study finds an effect that is not real (e.g., when a random variation appears to be a true effect). In a study of epidemiologic studies, a statistician examined the power of each of 71 clinical trials that reported no effect. He concluded that 70 percent of the studies did not have enough patients to detect a 25 percent difference in outcome between the experimental group and the control group. Even a 50 percent difference in outcome would have been undetectable in half of the studies. 11 This common weakness in epidemiologic studies is probably one reason for the contradictory results so often reported in the news.

History of influenza

Pandemic: an epidemic that has spread through many places in world Epidemic: refers to a condition that is occurring at a higher rate Endemic: a disease is spreading, but at rate you would expect it to (flu) Unclear yet whether the strain would kill people or cause more illnesses in 2009 the 2009 H1N1 virus emerged in 2009 causing the first global pandemic in more than 40 years

Types of Cohorts

Prospective • Everyone is free of disease at the start, we follow people over time see who develops disease and people over time, see who develops disease, and compare the groups Retrospective • We know who has the outcome of interest, but still divide into two groups based on past exposure and compare

Risk Assessment and Risk Perception

Public health's mission to protect the population from disease and injury requires governments to minimize risks or at least weigh risks against expected benefits, just as individuals do in their own lives. The formal process of risk assessment identifies events and exposures that may be harmful to humans and estimates the probabilities of their occurrence as well as the extent of harm they may cause. Risk assessment is often done on the basis of historical data: For example, one may predict that the number of motor vehicle crashes next year will be similar to the number this year, increasing or decreasing according to the trend established over the past several years. For many situations, however, there is little basis on which to make comparisons. In such cases, assessing risks involves making many assumptions, some of which may be little better than guesses. To estimate the probability of a mishap in a new technology, various possible chains of events are considered, and a risk for something going wrong is estimated for each step, perhaps by analogy with conventional technology. Risks of the individual steps are then added or multiplied to obtain a risk for the whole. This approach was used, for example, when nuclear power plants were first introduced, and it helped engineers to identify what kind of safety devices should be incorporated to reduce the probability of failure. According to an analysis published in 1987, experts said that the most risky activities and technologies were motor vehicles, smoking, alcoholic beverages, handguns, and undergoing surgery. Nuclear power, which was ranked 20th by the experts. Other risks that people tend to rank higher than the experts do are electromagnetic fields, genetic engineering, and radioactive waste. Risk perception researchers have found that people's concern about a risk is affected by certain associated factors. For example, familiar risks are more acceptable than unfamiliar ones. Risks that people perceive they have control over are more acceptable than those that are uncontrollable. A risk with potentially catastrophic consequences is unacceptable, even if it is highly unlikely to occur. People are more likely to accept a risk from an activity that is perceived as beneficial, but they want the risks and benefits to be distributed equitably. Risk perception researchers classify risks on two scales: Dread and knowability. The more dreaded the risk, the less acceptable it is; similarly, unknown risks are less acceptable than known risks. (FIGURE 7-2) maps various risks according to the concern they evoke on the two scales. Thus although driving an automobile is, statistically, one of the most risky activities, it does not arouse great anxiety because it is neither dreaded nor unknown. Moreover, people perceive that they have control when they are driving, and the benefit is obvious to them. Conversely, a nuclear reactor accident is highly dreaded, and thus is perceived by the public as more risky than the experts believe it to be. People perceive that they lack control over nuclear reactors, and the benefits of nuclear power may not be clear to people who live in their vicinity. The public's perception about nuclear power gained credibility after the 1979 accident at the Three Mile Island nuclear reactor in Pennsylvania. According to the experts, numerous safeguards were in place to prevent an accident, and the chance of a serious breakdown was remote. In fact, the safety systems worked to the extent that there was no disaster; no one was killed, and there was no significant radiation leak. Nevertheless, the fact that the breakdown occurred at all sent a signal that the experts may have underestimated the risks. The 1986 reactor meltdown at Chernobyl, in the Ukraine, further squelched interest in nuclear energy in the United States, as did the 2011 accident at the Fukushima Daiichi plant in Japan. No new plants have been opened in the United States, although a handful are under construction. 26 Concern about climate change caused by the burning of fossil fuels alters the risk- benefit balance for nuclear power. An interesting example of anomalous risk perception— one that is of great relevance to public health— is the paradox that adolescents so often engage in activities that they "know" to be dangerous, such as smoking, drunk driving, drug use, and unprotected sex. Studies aimed at understanding why teens engage in health-threatening behaviors can help to design interventions to prevent such behaviors. In the case of smoking, for example, surveys have shown that teenagers can fairly accurately predict the probability that smokers will die of lung cancer and other diseases. However, the same surveys have found that teenage smokers perceive themselves to be at little or no risk. It turns out that they plan to quit smoking in the next few years, an inaccurate perception because they underestimate the addictive nature of nicotine and the difficulty of quitting once they are addicted.

Quarantine

Quarantine: when people who are infected or suspected to have the infection is kept isolated in order to prevent infecting others - generally quarantine occurs under close medical supervision and is beneficial to the community as well as the patient. Quarantine: beneficial to the patient because they are monitored closely by other health professionals

Influenza virus

RNA core: genes that make proteins that helps virus survive Identity Surface of coat: things body might react to it Once body learns to attack, these two surface proteins can eliminate virus If body has previously seen it, can do it before people get sick has RNA core (8 gene segments) surrounding coat of proteins the most significant surface proteins are hemagglutinin and neuraminidase

Experiments on rats, rabbits, and monkeys have clarified the process by which high cholesterol and fat in the blood interact with other risk factors such as smoking, high blood pressure, and diabetes to form plaque in the arteries. These factors cause chronic injury of the artery's inner wall, which the body attempts to repair, leading to a "healing" process that runs wild, becoming a disease in itself. The higher the levels of cholesterol and other fats in the blood, the more they are incorporated into the scab-like buildup, and the faster the plaque forms.

Recent evidence suggests that atherosclerosis may also have an infectious component caused by bacteria that are often found in plaque. The blood cells in plaque are characteristic of an immune response and a number of chemicals in the blood suggest that atherosclerosis is an inflammatory condition like arthritis.

Measures of Association

Relative measure of comparison: based on ratio of two measures of disease frequency, this measure is generally called the risk ratio, the rate ratio, relative rate or relative risk

Influenza treatment

Resistance to medication: continue to use certain antiviral drugs too much can do resistance on individual level and public health level 2009- Did not have billions of medication available, if you had some medications- will make decision on who would get the treatment so maybe first come first serve or serve people who seem the most vulnerable

Study design- next step

Review the literature Review the literature • Select a study type or design that fits the research question • Develop the protocol • Pilot test study protocol • Collect data • Analyze data • Write the report and disseminate findings

What term correctly fills in the blank in the following sentence: Smoking is a(n) ________ for lung cancer.

Risk Factor

Mammograms to detect breast cancer are an example of

Secondary prevention

Criteria for effective screening

Should detect it early on before it becomes more serious Screening should be tested before and has been proven effective and appropriate follow up available for those who test positive (if there is a cist or abnormality in the breast and if there are no follow up measures it can cause more distress in the individual Access to diagnosis and follow up so that a good screening is followed by a diagnostic test followed by early intervention treatment and cure Life threatening disease Treatment of diseases at their earlier stages should be more effective than treatment begun after the development of symptoms. The prevalence of the detectable preclinical phase of disease has to be high among the population screened. A suitable screening test must be available. Appropriate follow-up of those individuals with positive screening results to ensure thorough diagnostic testing occurs.

Which one of these is NOT an emerging threat?

Smallpox

Statistics of screening

Statistics of Screening In public health's mission to prevent disease and disability, secondary prevention— early detection and treatment— plays an important role. When the causes of a disease are not well understood, as in breast cancer, little is known about primary prevention. The best public health measure is to screen the population at risk so as to detect the disease early, when it is most treatable. Screening is also an important component of programs to control HIV/ AIDS by identifying HIV-infected individuals so that they can be treated and counseled about how to avoid spreading the virus to others. As discussed later in this volume in the section of genetic diseases, newborn babies are routinely screened for certain congenital diseases that can be treated before permanent damage is done to the infants' developing brains and bodies. Tests may be highly sensitive, meaning that they yield few false negatives, or they may be highly specific, meaning that they yield few false positives. Many highly sensitive tests are not very specific and vice versa. For most public health screening programs, sensitive tests are desirable in order to avoid missing any individual with a serious disease who could be helped by some intervention. When a positive result is found, more specific tests are then conducted to determine if the first finding was accurate. For example, if a sensitive mammogram finds a suspicious spot in a woman's breast, the test is usually followed up with a biopsy to determine whether the spot is indeed cancerous. When screening is done for rare conditions, the rate of false positives may be as high as or higher than the number of true positives, leading to a lot of follow-up testing on perfectly normal people. Such a situation occurred in 1987 when the states of Illinois and Louisiana mandated premarital screening for HIV. 16 With the rate of HIV infection in the general, heterosexual population quite low, a great many healthy people were unnecessarily alarmed and subjected to further tests, while very few HIV-positive people were identified. Some couples went to neighboring states to marry to avoid the nuisance. The programs were discontinued within a year. There are other conditions for which screening may not be as beneficial as expected. One of these is prostate cancer, discussed elsewhere in this text. Another is lung cancer screening of smokers. Lung cancer is usually a fatal diagnosis; by the time most patients suffer symptoms, it is too late for medicine or surgery to make a difference. The idea of screening smokers so that cancers can be detected and treated earlier in the course of the disease has been around since the 1970s and 1980s. However, at that time, the only method of screening was to use chest x-rays, and it turned out that cancers detected by x-ray screening were almost always too far advanced to be treatable. screening with spiral CT scans (a kind of three-dimensional x-ray) could detect lung cancers early enough that treatment allowed 80 percent of patients to survive for ten years, compared to a 10 percent survival rate for patients who had been diagnosed the usual way. 17 A few months later, the Journal of the American Medical Association published another study, concluding that spiral CT scanning does not save lives and may actually cause more harm than good. 18 An analysis of the findings of the first trial revealed two sources of bias: lead-time bias and overdiagnosis bias. 19 The former may occur in all cancer screening and must be taken into consideration before concluding that screening saves lives. Lead-time bias occurs when increased survival time after diagnosis is counted as an indicator of success. If early detection of a cancer does not lead to a cure, the only result of early diagnosis is that patients will live longer with the knowledge that they are sick before dying at the same time they would have died anyway. This appears to be the case in the New England Journal of Medicine study of lung cancer screening. In fact, the effects of the additional diagnostic tests and surgeries that follow the early diagnosis may hasten the patients' death. Overdiagnosis bias occurs when the tumors that are detected by the screening are not likely to progress to the stage that they cause symptoms and be life-threatening. Such small tumors had also been found in the earlier lung cancer screening trials using x-rays. Overdiagnosis bias is also a problem with prostate cancer screening, and perhaps with breast cancer screening, as discussed earlier in this chapter. The only way to be sure that screening actually saves lives is to conduct randomized controlled trials, comparing mortality among patients who are screened with that of patients who are not screened.

An epidemiologist investigating an outbreak of encephalitis in New York City reports that there have been 17 new cases this week. Incidence of encephalitis is the best term that describes the number he reports:

TRUE

Randomization makes the treatment and control groups more comparable.

TRUE

Which of the following is not included in influenza surveillance?

Water Surveillance

Which of the following statements about measles is not true

Wild animals are a reservoir for measles

Noncompliance

• Overt • The participants notify the researchers that they are dropping out • Loss to follow-up Covert • Stop taking the assigned treatment without telling the researchers • Compliance assessments are very important • If a medication, we can test urine, ask patients to bring back pill bottle to count the remaining pills, use questionnaires • If behavioral intervention, we can track attendance (how many sessions did the participant come to) Covert: Don't know this is occurring, need to build compliance tests to make sure they understand how treatment is taken by participant

Preventive vs. Therapeutic

• Preventive • Does pre- and/or post-exposure prophylactic medication given to HIV-uninfected healthy or high-risk individuals prevent acquisition of HIV-infection Does a vaccination given to healthy or high risk individuals prevent a disease? Therapeutic • Does treatment given to individuals with breast cancer reduce or eliminate cancer cell replication, reduce risk of recurrence, improve survival and quality of life? Does treatment given to diseased individuals reduce the risk or re occur or quality of life?

Generalizability

• Internal Validity • Extend to which the study groups are comparable • Affected by selection and randomization • Are the results generalizable to the study sample? • External Validity • Extent to which the results can be applied to people not in the study • Generalizability • Representativeness of the population from which the sample was drawn

Issues in Experimental Studies

• Loss to follow-up • Noncompliance • Generalizability • Ethical considerations

Randomization that worked well

Secondary purpose: create equal groups Cardiovascular disease: outcome of interest Groups are comparable

Restricting individual freedoms for public health purposes is NEVER constitutional.

FALSE

The chain of infection includes understanding the immunization, the pathogen and the reservoir.

FALSE

Vaccination recommendation in 2013 recommends all person, regardless of age, should be vaccinated annually.

FALSE

Exposures versus outcomes

"Exposures" Smoking could be a researchable outcome for health behavior scientists "Outcomes" Prostate cancer could be an exposure for another scientists. researcher, divided into stages to research mortality research mortality One person's exposure is another person's outcome

Several drugs appear to show promise in treating Ebola, although none has yet proved itself effective in a clinical trial. ZMapp, a combination of three antibodies, proteins that can attach to the virus and neutralize them, has shown promise in monkey studies.

- A drug called favipiravir, developed in Japan as a treatment for influenza, works by interfering with the virus's ability to copy itself. It was given to a number of patients in Guinea and appeared to be helpful in patients whose viral load was low to moderate. It was given to a number of patients in Guinea and appeared to be helpful in patients whose viral load was low to moderate. - An older anti-Ebola drug, TKM-Ebola, created to fight the strain prevalent in an earlier outbreak in Central Africa, has been adapted to the current West African strain and was found to be effective in treating monkeys infected with the virus. In March 2015, a clinical trial of TKM-Ebola was launched in Sierra Leone, where the disease was still spreading. - An older anti-Ebola drug ,TKM-Ebola, created to fight the strain prevalent in an earlier outbreak in Central Africa, has been adapted to the current West African strain and was found to be effective in treating monkeys infected with the virus. In March 2015, a clinical trial of TKM-Ebola was launched in Sierra Leone, where the disease was still spreading.

Bacteria, which a few decades ago seemed easily controllable because of the power of antibiotics to wipe them out, have, like viruses, emerged in more deadly forms.

- A great cause for concern is the development of resistance to drugs. Resistance can spread among pathogens of the same species and even from one bacterial species to another. Legionnaires' disease and Lyme disease are not new, but only recently have they become common enough to be recognized as distinct entities and for their bacterial causes to be identified. Legionella bacteria were able to flourish in water towers used for air conditioning. Regulations requiring antimicrobial agents in the water have been effective in limiting the spread of Legionnaires' disease. - The pathogen that causes Lyme disease was identified in 1982 as a spirochete that is spread by the bite of an infected deer tick. - The reservoir for Lyme disease is the white-footed mouse, on which the deer tick feeds and becomes infected. Deer, on which the ticks grow and reproduce, are an important step in the chain of infection, and it is because of the recent explosion in the deer population in suburban areas that Lyme disease has now become such a problem for humans. Infection with streptococci, the bacteria that cause strep throat, had normally been easily cured with penicillin. - However, for reasons that are not well understood, a more lethal strain of the bacteria, called group A streptococci, has become increasingly common. The sudden death of Muppets puppeteer Jim Henson in 1990 from fulminating pneumonia and toxic shock was caused by this new, virulent strain. The headline-grabbing "flesh-eating bacteria" that infect wounds to the extent of necessitating amputations and even causing death are also group A streptococci.

In the United States, HIV/ AIDS has become a disease of minorities

- Although African Americans make up only about 12 percent of the U.S. population, almost half of new cases being diagnosed in recent years are among blacks. According to the Centers for Disease Control and Prevention (CDC), in 2013, the rate of infection was almost seven times higher in black men than in white men and 15 times higher in black women than white women. Hispanics are diagnosed at three times the rate of whites. Among the factors that contribute to the higher rates among minorities are the fact that people tend to have sex with partners of the same race and ethnicity; minorities tend to experience higher rates of other sexually transmitted diseases, which increase the risk of transmission of HIV; socioeconomic issues associated with poverty; awareness of HIV status, and perceptions about HIV testing

In 2014, a major Ebola epidemic spread through the populations of several countries in West Africa. Hardest hit were Liberia, Guinea, and Sierra Leone, poor countries that have been plagued by political unrest and inadequate medical care systems. Ebola spread easily to healthcare workers and to family members who cared for patients. Corpses of people who died of the disease teemed with the virus, and the West African funeral customs of touching and kissing the dead contributed to the contagiousness of the disease.

- An explosion of cases in Sierra Leone was triggered by the funeral of a traditional healer in early summer. 29 Medical workers learned to don protective clothing that covered all surfaces of their bodies. However, in the heat of the West African summer, it was hard for workers to spend much time in such cumbersome garb. - More than 28,600 cases, with about 11,300 deaths, have been reported in the West African epidemic This time, the virus came to the United States. The first patient was a Liberian man who became ill while visiting relatives in Dallas, Texas in September 2014. Thomas Eric Duncan was taken to a hospital, examined, and sent home with antibiotics. Although hospital staff were told he had been in Guinea, the information did not trigger alarm, and Ebola was not suspected. Three days later, Duncan's condition worsened and he was taken back to the hospital, where he died on October 8.

Improper use of antibiotics favors the development of resistance, and the current widespread existence of resistant bacteria testifies to the carelessness with which these life-saving drugs have been used. For example, since antibiotics are powerless against viruses, the common practice of prescribing these drugs for a viral infection merely affords stray bacteria the opportunity to develop resistance.

- Another example of improper use is the common tendency of patients to stop taking an antibiotic when they feel better instead of continuing for the full prescribed course A practice that significantly contributes to antibiotic resistance is the widespread use in animal feeds of low doses of antibiotics for the purpose of promoting the growth of livestock and to prevent disease among animals living in crowded, unsanitary conditions. - More antibiotics are used in this manner than in medical applications, and the practice has clearly led to the survival of resistant strains of bacteria that may not only contaminate the meat but that may also spread the antibiotic resistance genes to other bacteria. - Studies have shown that these "superbugs" can be transmitted to humans. The bacteria Salmonella and Campylobacter are estimated to cause 3.8 million cases of food-borne illness in the United States each year. In a 1999 study, 26 percent of the salmonella cases and 54 percent of the campylobacter cases were found to be resistant to at least one antibiotic, probably because of antibiotic use in animal feed. Infection with methicillin-resistant Staphylococcus aureus (MRSA) is a major problem in hospitals, burn centers, and nursing homes, where hospital staff may carry the bacteria from one vulnerable patient to another. succeeded in reducing the rates of MRSA infections in hospitalized patients by 54 percent between 2005 and 2011

Public health measures to control the spread of disease are aimed at interrupting the chain of infection at whichever links are most vulnerable.

- At link 1, the pathogen could be killed, for example, by using an antibiotic to destroy the disease-causing bacteria. - At link 2, one could eliminate a reservoir that harbors the pathogen. For example, controlling rat populations in cities by picking up garbage is a way of preventing the spread of plague to humans. Adequate water and sewage treatment prevents the spread of water-borne diseases, and proper food-handling methods eliminate reservoirs of food-borne pathogens. - At link 3, transmission from one host to another could be prevented by quarantining infected individuals, for example, or by warning people to boil their water if the water supply becomes contaminated. Hand washing is an important way to prevent the spread of disease: it prevents restaurant workers from contaminating food, hospital workers from carrying pathogens from one patient to another, and allows all individuals to protect themselves against pathogens they may pick up from the environment and put in their mouth. The spread of sexually transmitted diseases can be prevented by use of a condom, a simple matter of blocking the movement of the pathogens to the uninfected person. - At link 4, the resistance of hosts can be increased by immunization, which stimulates the body's immune system to recognize the pathogen and to attack it during any future exposure. Vaccination not only keeps the individual from contracting a disease but also makes it harder for the pathogen to find susceptible hosts. - Possible to completely eliminate a pathogen from the earth by eliminating the susceptibility of its potential hosts. Other links are often included separately as part of the chain of infection when it is useful to consider them as sites for public health intervention For example, the port of entry into the host for a mosquito-borne disease would be the skin, a link that could be interrupted if the potential host wears long sleeves and gloves. Similarly, the place of exit is the route by which the pathogen leaves the host

The classic public health measures of surveillance and quarantine were key components in combating severe acute respiratory syndrome (SARS), a highly infectious new disease that first broke out in southern China in November 2002

- Because China did not at first report the disease, it was not recognized as a major threat until March 2003, when the World Health Organization (WHO) issued a global alert and a travel advisory - WHO had been alerted by Dr. Carlo Urbani, an infectious disease specialist working in Vietnam, who noticed that a patient who had recently arrived in Saigon from Hong Kong was suffering from an atypical form of pneumonia. - Epidemiologic detective work found that the patient in Saigon, as well as patients soon identified in Toronto and Singapore, had all stayed in the same hotel in Hong Kong where a traveler from southern China had spent one night before falling ill with the syndrome - Who declared that SARS had been contained, the disease had infected 8439 people in 30 countries and had killed 812 people. SARS was contained by old-fashioned measures: quickly isolating patients who were suspected to have the disease— because of fever, cough, and previous contact with a known SARS patient— and quarantining anyone who had come in contact with them.

Scientists conjecture that the human form of the virus may have existed in isolated pockets of Africa for some time, but that its rapid spread was the result of social conditions in Africa and the United States in the late 1970s.

- Because symptomatic AIDS does not appear until several years after the original infection, the first victims of the 1980s were probably infected in the early and mid-1970s. Investigators trying to track the early spread of the epidemic have gone back to test stored blood samples drawn in earlier times, and they have found HIV-infected samples from as early as 1966, in the blood of a widely traveled Norwegian sailor who died of immune deficiency. - An even older blood sample drawn from a West African man in 1959 has been found to contain fragments of the virus, but it is not known whether the man developed AIDS. This evidence implies that sporadic early outbreaks of the disease occurred in isolated African villages, going undetected for decades. The reasons for the recent emergence of HIV disease as a significant problem include the disruption of traditional lifestyles by the movement of rural Africans to urban areas, trends magnified by population growth, waves of civil war, and revolution. The

By 1958, routine immunization had eliminated smallpox in the United States and other industrialized countries. However, it was still widespread in 33 underdeveloped countries, killing two million people per year. With support from both the United States and the Soviet Union, WHO developed plans for a program to eliminate smallpox.

- Because the lesions of smallpox were so conspicuous, it was possible for the investigators to track outbreaks by showing pictures of victims and asking people if they knew of anyone with this disease.' - The decision to destroy the virus was controversial, with some scientists believing that valuable information might be gained in future studies using techniques that were not yet known. In 1999, WHO decided to defer the destruction for a few more years. - Meanwhile, word was leaking out of the former Soviet Union that the Soviets had been working on smallpox as a bioweapon. There were fears that they had shared their stocks of the virus with rogue states such as Iraq and North Korea. The anthrax attacks of 2001 further raised fears about bioterrorism. One concern with smallpox is that the molecular sequence of the virus is publicly known, meaning that, even if all smallpox viruses are eliminated, someone could synthesize it in a laboratory and loose it on the world.

That MDR TB can be a threat to all strata of society was made clear by an epidemic that was finally recognized in a suburban California school in 1993.

- By the time the county authorities took over her case in 1993, the girl had developed a drug-resistant strain. In accordance with standard public health practice, the health department then began screening all the girl's contacts for tuberculosis infection. Some 23 percent of the 1263 students given the tuberculin skin test were found to be positive for exposure to the infection. Of those, 13 students had active cases of the drug-resistant strain of the disease. Fortunately, no one died. New York City has proven that, by applying public health measures, it is possible to reverse the trend of increasing MDR TB, a trend that had been worse in that city than anywhere else in the nation. In 1992, the number of tuberculosis cases diagnosed in the city had nearly tripled over the previous 15 years, and 23 percent of new cases were resistant to drugs. The city and state began intensive public health measures, which included screening high-risk populations and providing therapy to everyone diagnosed with active tuberculosis. A program of directly observed therapy (DOT) was instituted for patients who were judged unlikely to take their medications regularly. Outreach workers traveled to patients' homes, workplaces, street corners, park benches, or wherever necessary to observe that each patient took each dose of his or her medicine.

Smoking is believed to increase the risk of cardiovascular disease through the actions of two components of tobacco smoke: nicotine and carbon monoxide. Nicotine, the addictive component of tobacco, is a stimulant that raises blood pressure, increases the pulse rate, stimulates release of stress hormones, and increases irritability of the heart and blood vessels.

- Carbon monoxide, a poisonous gas, binds to hemoglobin in the blood, blocking the hemoglobin's ability to carry oxygen throughout the body. - Both nicotine and carbon monoxide place stress on the heart and blood vessels, with the long-term effect of contributing to atherosclerosis. In the short term, the effects of nicotine and carbon monoxide can provoke irregularities in heartbeat, which may result in sudden death. - One epidemiologic study found that smokers in this age group have a five times greater rate of heart attacks than nonsmokers.

Bats are the most dangerous rabies threat to humans. Even in parts of the country where the disease is not endemic among most wildlife, rabid bats are likely to be found. Because the animals are nocturnal and elusive, contact with bats may go unnoticed.

- During the period between 2003 and 2013, 20 of the 36 cases of human rabies in the United States were caused by a strain of the virus that is associated with bats. Many of these victims were not aware of having been bitten by a bat and did not realize that any exposure to bats might constitute a rabies risk. - Of the 13 cases not attributable to bats, eight were caused by dog bites outside of the United States, three were from a viral strain associated with raccoons, one was from a fox bite in Mexico, and one was suspected to be caused by a feral cat in California - One patient who died in 2013 was found to have contracted the virus through a kidney transplant. The donor's cause of death was not recognized as rabies, but later was found to have had the same raccoon strain as the transplant recipient. Three other recipients of organs from the same donor were offered post-exposure prophylaxis. By the time the puppy was diagnosed, the animals had been dispersed to 16 states around the country. Concerned that the puppy might have bitten other animals in the group, federal and state public health workers tracked them all down, vaccinated them and placed them in quarantine for six months. 11 As a result of this incident, the Centers for Disease Control and Prevention (CDC) issued new regulations on the importation of animals to the United States

Progress in treating HIV/ AIDS over the past two decades has been dramatic.

- Early therapy focused on treating opportunistic infections, which were often the immediate cause of death in AIDS patients. The first antiretroviral therapy, zidovudine (AZT), was approved by the Food and Drug Administration (FDA) in 1987.The drug interfered with the replication of HIV by inhibiting the enzyme that copies the viral RNA into the cell's DNA. However, the virus's tendency to mutate rapidly leads to the development of resistance to the drug, meaning that its effectiveness can wear off. - Protease inhibitors, which interfere with the ability of newly formed viruses to mature and become infectious, were introduced in 1995. - At the same time, scientists recognized that treating patients with a combination of drugs that attack the virus in different ways reduces the opportunity for HIV to mutate and develop resistance. The introduction of these drug combinations, called highly active antiretroviral therapy (HAART), led to dramatic improvements in the survival of HIV-infected patients. As a result, the number of AIDS deaths fell by more than half between 1996 and 1998 and has continued to decline since then. - The development of effective treatments for HIV/ AIDS has had many beneficial consequences. HAART can reduce viral load to undetectable levels in the blood and body fluids of many patients, which greatly reduces the likelihood that the virus will be transmitted to others through sexual contact and other means. The availability of effective therapy also encourages at-risk people to be tested and counseled on ways to protect themselves and to prevent transmission of the virus to others. Scientists hoped that HAART would be able to completely eradicate HIV from the body, but this hope has not been realized. The virus manages to survive in protected reservoirs of the body, rebounding into active replication when the drugs are withdrawn. - For some patients, side effects of the drugs can be severe and even fatal; about 40 percent of patients treated with protease inhibitors develop lipodystrophy, characterized by abnormal distributions of fat in the body, sometimes accompanied by other metabolic abnormalities. New drugs continue to be developed, including a class called "fusion inhibitors," introduced in 2003, which interfere with HIV's ability to enter a host cell, and a class called integrase inhibitors, introduced in 2002, which prevents the virus from integrating into the genetic material of human cells. A totally new approach, published in 2014 but not ready for clinical application, uses genetic engineering to knock out a receptor on the membrane of T cells, making them resistant to HIV.

More often, the public health response when an outbreak is detected by surveillance is to locate people who have had contact with the infected individual and to immunize them or give them medical treatment, as appropriate

- For tuberculosis, contact tracing is used in addition to quarantine: people who have been exposed to the patient are given prophylactic doses of antibiotics. - Contact tracing is also routinely used for controlling sexually transmitted diseases, such as syphilis and gonorrhea - Syphilis, which tends to affect the poor, the homeless, drug users, and prostitutes, can be diagnosed by a blood test - Once a case is identified, public health workers try to discreetly alert those who have been exposed. The public health worker asks the person who has been diagnosed to identify sexual contacts; the worker then notifies the contacts that they have been exposed without identifying the source of the exposure. Syphilis is readily cured by penicillin. If untreated, it may cause long-term damage to the heart and brain; congenital syphilis in infants born to infected mothers can be lethal

The major pathways of HIV transmission vary in different populations.

- Homosexual relations between men are still the leading route of exposure for men in the United States. Injection drug use accounts for 10 percent of new HIV infections in Americans. - Transmission by heterosexual relations, especially male to female, is becoming increasingly common in this country; it is the leading route of infection for females. - The sharing of needles is a common route of transmission in developing countries because of insufficient supplies of sterile equipment for medical use. - In poor countries, including Russia and some nations in Eastern Europe, medical personnel often use one syringe repeatedly for giving immunizations or injections of therapeutic drugs. If one of the patients is HIV positive, this practice may transmit the infection to everyone who later receives an injection with the same needle. - According to the World Health Organization (WHO), 40 percent of injections worldwide are given with unsterile needles. - A special case of HIV transmission occurs from mother to infant, in utero or during delivery, in 25 to 33 percent of births unless antiretroviral drugs are given. The virus can also be transmitted to breast-fed babies in their mother's milk. All infants of HIV-positive women will test positive during the first few months after birth. This is because fetuses in the womb receive a selection of their mothers' antibodies, providing natural protection against disease (though not HIV) during their first months of life.

Although known to infect monkeys, the primary hosts for monkeypox are rodents.

- However, the incident raised alarms about exotic pets. The illness in the prairie dogs was traced back through pet stores and animal distributors to an Illinois distributor, who in April had imported several African rodents, including a Gambian giant rat that had died of an unidentified illness. In June 2003, the U.S. government banned the import of all rodents from Africa. Careful surveillance and isolation of exposed people and animals halted the outbreak by the end of July, and no further cases of monkeypox have been reported since then. Named after the Hantaan River in Korea, the hantavirus had been responsible for kidney disease among thousands of American soldiers in Korea during the 1950s. In New Mexico, the virus was found to be carried by deer mice, which had been unusually plentiful in the Four Corners area because of an unusually wet winter. All of the human victims of hantavirus had had significant exposure to mouse droppings, either in their homes or in their places of work. - Rodents are suspected as carriers of several hemorrhagic fevers with symptoms similar to those caused by hantavirus or the Ebola virus: Bolivian hemorrhagic fever (caused by the Machupo virus), Argentine hemorrhagic fever (caused by the Junin virus), and Lassa fever in Sierra Leone are all carried by rats. Well-known, insect-borne viruses, such as yellow fever and equine encephalitis, are resurgent in areas of South and Central America where they had been thought to be vanquished.

One of the reasons China is an especially fertile source of new flu strains is that animal reservoirs for influenza— pigs and birds— are common there, living in close proximity to humans.

- Human and animal influenza viruses incubate in a pig's digestive system, forming new genetic combinations, and are then spread by ducks as they migrate. While such hybrid viruses, containing human and animal genes, are only rarely capable of infecting humans, those that are able to do so are the most likely to be deadly. Thus influenza experts were alarmed in 1997, when a 3-year-old Hong Kong boy died from a strain of influenza virus that normally infected chickens. There had been an epidemic of the disease in the birds a few months earlier. Antibodies to the virus were found in the blood of the boy's doctor, although he did not become ill, and public health authorities watched for more cases with great concern. - To prevent further transmission from chickens to humans, the Hong Kong government ordered that all 1.5 million chickens in the territory be killed. Bird flu emerged again in 2003 and has become widespread in Asia, Africa, Europe, and the Middle East, despite efforts to eliminate it by killing millions of birds. - Thus far it appears that most of the human victims of the bird flu caught the virus from chickens, not from other humans. There is great concern that mixing of the viral genes could occur in a person infected with both the bird virus and a human flu virus, resulting in a much more virulent strain capable of spreading among humans. An outbreak of avian influenza struck the United States in spring 2015. Millions of turkeys and chickens have died or been culled in Midwestern states. No humans have caught this flu, but there is concern that it might happen. - shares some genes with the avian flu that infected poultry in Asia and Europe, is believed to have been carried to this continent by migrating ducks, geese, and swans. The National Institutes of Health developed an experimental vaccine against the bird flu when it first affected humans in Asia. The CDC is considering whether it might provide some protection to workers dealing with infected flocks. It is also working on a vaccine against the new virus.

In the 1990s, even more threatening strains of tuberculosis began to appear around the world— extensively drug-resistant tuberculosis (XDR TB). While strains of MDR TB are resistant to the most common anti-TB drugs, there are still some drugs that are effective against them, although they are more expensive and are difficult to administer. XDR TB is resistant to virtually all antituberculosis drugs, leading to a mortality rate of 50 percent or more. According to one expert, this raises "concerns about a return to the pre-antibiotic era in TB control."

- In May 2007, an American lawyer, Andrew Speaker, caused an international health scare when, after being tested for tuberculosis in Atlanta, he flew to Paris to be married in Greece and spend his honeymoon in Europe. When the test results came in a few days later, showing that he had XDR TB, the CDC contacted him in Rome and recommended that he make arrangements for medical treatment there. - The incident inspired headlines around the world as U.S. authorities tried to locate Mr. Speaker and to track down passengers and crew members on the two trans-Atlantic flights so that they could be tested for the infection. Back in the United States, Mr. Speaker was held in isolation and eventually had surgery to remove the infected portions of his lung. Further tests showed that he did not have XDR TB after all, although his infection was MDR TB. 85 The incident presumably inspired the development of Do Not Board lists, as described above.

Research into the causes of chronic disease, like research into the causes of infectious disease, relies on epidemiologic methods and laboratory research, which usually includes studies of animals as models, or stand-ins for human patients. The importance of research on animal models to the understanding of human disease cannot be overemphasized. Epidemiology is generally limited to observation and analysis of events that occur spontaneously.

- In experiments on laboratory animals, scientists can carefully control the conditions so that cause-and-effect relationships can be clearly proven. Mice and rats are the most commonly used laboratory animals; as mammals, they share the majority of biochemical and physiological processes with humans. Because of their short life spans, the effects of various exposures and interventions can be studied over the lifetime of the animals.

The greater concern is saturated fat and trans fat, as well as a deficiency of fruit and vegetables.

- In humans, as in rabbits, vegetarians have lower cholesterol levels than meat eaters. Vigorous exercise lowers total cholesterol and increases HDL - Moderate consumption of alcoholic beverages has a similar effect, although heavy drinking damages the heart. - Other dietary substances such as fish, olive oil, and oat bran also appear to have favorable effects on blood lipids. - Smoking lowers HDL levels. Genes play an important role in the HDL- LDL balance. Some people can eat lots of fat with very little effect on their blood cholesterol, while others must work much harder to maintain favorable levels

As chronic degenerative diseases became a growing problem during the 20th century, scientists began to focus on efforts to understand their causes. The growth of the National Institutes of Health (NIH), which sponsors most biomedical research in the United States, has reflected the growth of concern about these diseases.

- In its early days as a one-room Laboratory of Hygiene that opened in 1887, the NIH conducted research primarily on infectious diseases. Congress created the National Cancer Institute in 1937 and the Heart Institute— now called the National Heart, Lung, and Blood Institute (NHLBI)— in 1948. Currently there are 27 different institutes and centers, each of them focused on a different organ or problem, mostly chronic diseases. One institute, for example, is concerned with arthritis, one with diabetes, and one with neurological disorders and stroke.

The measles outbreaks in 2011 and 2014, discussed above, illustrate the dangers of leaving children unvaccinated.

- Most of the cases were linked to people who had traveled abroad or visited from another country and spread the virus to unvaccinated children in this country. - It is often in wealthy communities that parents refuse to subject their children to the small risk of immunization. - However, much of the protection afforded by a high rate of immunization in a population comes from "herd immunity," the phenomenon by which even infants too young to be vaccinated and people with weakened immune systems for various reasons, as well as those who refuse to be immunized, are unlikely to be exposed to a disease because the majority of the population is immune. If the percentage of immunity in the population falls too low, however, outbreaks are likely. Then even vaccinated people are at risk, because no vaccine is perfect. In Orange County, California, where Disneyland is located, some private schools have immunization rates as low as 60 percent. Parents of children with cancer and other conditions that preclude vaccination are becoming increasingly angry at the risk their children are being exposed to as a result of other parents' refusal to vaccinate their children. 32 The news about the Disneyland measles outbreak led California to put an end to the personal belief exemption in 2015

Tuberculosis, which is spread by aerosol, used to be a major killer in the United States. Between 1800 and 1870, it accounted for one out of every five deaths in this country. Worldwide, it is still the leading cause of death among infectious diseases.

- Much of the success came from the early public health movement, which emphasized improvement of slum housing, sanitation, and pasteurization of cows' milk, which harbored a bovine form of the bacillus that was pathogenic to humans. - With the introduction of antibiotics in 1947, mortality from tuberculosis was dramatically reduced, sanatoriums were closed, and tuberculosis seemed vanquished. In 1985, however, the trend reversed. There were several reasons for the increase in the incidence of tuberculosis, which was particularly concentrated in cities and among minority populations. The HIV epidemic was certainly a major factor. - People with defective immune systems are more susceptible to any infection, but HIV-positive people are especially vulnerable to tuberculosis. An increasing homeless population and the rise in intravenous drug use, both of which are associated with HIV infection, were also factors in increasing tuberculosis rates. Homeless shelters, prisons, and urban hospitals are prime sites for the transmission of tuberculosis.

The better outcomes achieved by American patients, compared with the high death rate among West Africans— which in some West African countries was more than 70 percent— is due in part to excellent supportive care provided them in U.S. hospitals.

- One measure some of them received was transfusion with serum from survivors, which contains antibodies to the virus. Some patients were treated with ZMapp, an experimental drug. Whether either of these treatments contributed to their survival is not certain and would need to be tested in a clinical trial. - A surprising finding has been that, even after a patient appears to be fully recovered, the virus may linger in his/ her body. Male survivors have been warned to use condoms because their semen contains Ebola virus for a still unknown period after recovery. Many of the survivors have also reported other aftereffects of the disease, including extreme fatigue, joint and muscle pain, and hearing loss.

The identification of an animal model can significantly improve progress toward understanding a disease. It is not always easy to find an experimental animal that is susceptible to the disease one wishes to study. For instance, there is no good animal model for AIDS, a fact that has hampered progress in developing drug therapies or vaccines. Asian macaque monkeys, which can be made sick by simian immunodeficiency virus, a relative of human immunodeficiency virus (HIV), are the closest substitute.

- Only chimpanzees can be infected with HIV, and chimps are no longer used for research for ethical reasons and cost. Animals also differ in how they metabolize some chemicals; a dose of dioxin that would kill a guinea pig has no effect on a mouse or rat, and it is difficult from this evidence to predict the chemical's toxicity to humans.

The greatest hope for controlling AIDS, especially in the developing world where the new drugs are unaffordable, is to develop an effective vaccine. Prevention through immunization has been the most effective approach for the viral scourges of the past, including smallpox, measles, and polio. Early hopes for the rapid availability of a vaccine against AIDS have faded, however. In fact, after several promising vaccine candidates failed in clinical trials, the National Institutes of Health (NIH) held a meeting of vaccine researchers in March 2008, to reassess whether a vaccine will ever be possible and what new approaches could be tried.

- Part of the difficulty in developing an effective vaccine is that the virus itself is constantly changing its appearance, making it unrecognizable to the immune mechanisms that are mobilized against it by a vaccine. This quality is common to RNA viruses. Another difficulty is that there is no good animal model for studying HIV/ AIDS. - At present, the most effective way to fight AIDS is to prevent transmission (step 3 in the chain of transmission). This requires education and efforts at motivating people to change their high-risk behavior, an exceedingly difficult task. - Genetic studies of HIV show that it is related to viruses that commonly infect African monkeys and apes, and it seems likely that a mutation allowed one of these viruses to infect humans. evidence that this type of event— cross-species transmission of viruses— may occur fairly frequently. Monkeys and chimpanzees are killed for food in parts of Africa, which could explain how humans were exposed. HIV is remarkable, however, for the speed with which it has spread into the human population worldwide.

It has been known for decades that atherosclerosis— hardening of the arteries— is part of the development of cardiovascular disease.

- Pathologists performing autopsies on people who died of heart attacks found, within the inner-wall lining of the deceased's arteries, a buildup of plaque composed of fat and cholesterol, blood cells, and clotting materials. The formation of plaque begins at an early age in the United States. Fatty streaks, the first stage in the development of plaque, have been found on autopsy in half the children aged 10 to 14 who died of accidental causes. - A classic study, published in 1955, examined the arteries of American soldiers killed in the Korean War and found that 77 percent of the men, whose average age was 22, showed some signs of atherosclerosis. 3 More recent studies have confirmed these findings and have shown that plaque was more likely to be found in adolescents and young adults with risk factors such as smoking, hypertension, obesity, and high levels of low-density lipoprotein cholesterol. - Animal studies showed that diet plays a role in the formation of plaque. Rabbits fed milk, meat, and eggs instead of their normal vegetarian diet were found to develop atherosclerotic plaque very similar to that found in humans. American diet was due to the high rate of cardiovascular disease

India has made major effort to vaccinate children with repeated rounds of National Immunization Days each year, but in poverty-stricken areas of the country children suffering from other intestinal infections tend not to develop immunity even after multiple doses of the vaccine.

- Political upheaval has interfered with immunization campaigns in some countries. In Pakistan and Nigeria, for example, polio vaccinators have been killed by Islamic extremists. Some experts have argued that the goal of eradicating polio is unrealistic and that efforts should be focused on "control" rather than eradication. Other vaccine-preventable diseases are being neglected because of the intensive effort on polio, that the campaign has been going on too long and has become too expensive. However, India was removed from the list of endemic countries in 2012, giving hope that success can be achieved elsewhere, and the effort continues.

Rabies

- Rabies, a fatal disease of the nervous system caused by a virus, kills an estimated 60,000 people around the world each year, usually contracted through a dog bite. - In the United States, transmission of the disease to humans is very effectively prevented by routine public health measures. Although there is an effective human vaccine against rabies, routine immunization of everyone is not recommended - The rabies virus infects only mammals, and it is almost always transmitted when a rabid animal bites another animal or a human. - Since the animal most likely bit a human is the dog, mandatory immunization of dogs against rabies is the first line of defense in the protection of people. Wild animals serve as the reservoir of rabies, and dogs are most likely to be exposed by being bitten by a rabid wild animal. Domestic cats are also at risk for exposure to rabies from wildlife, and immunization is recommended for them as well. - Because immunization of dogs is widespread in the United States, less than 100 cases of rabies occur annually in the 60 million dogs in this country, and a dog bite is considered unlikely to transmit the disease. If the biting dog (or cat) appears to be healthy, it need only be observed for 10 days to ensure that it remains healthy. - Rabies virus affects the brain and from there travels to the salivary glands and is secreted in saliva. An animal capable of transmitting the virus in its saliva will already have brain involvement, exhibit symptoms, and be dead within a few days. That is sufficient time for the bitten person to be given the series of vaccinations that will protect him or her from the disease.

Cardiovascular disease encompasses two of the three leading causes of death in the United States: heart disease and stroke.

- Risk for dying from cardiovascular disease increases with age, is higher in men than in women, and is higher in blacks than in whites The causes of cardiovascular disease have been relatively well established through epidemiologic studies, including the Framingham Study, which identified high blood cholesterol, high blood pressure, and smoking as major risk factors.

Smallpox is an example of no bacterial agent to be found

- Smallpox was known to be transmitted from a sick person to a healthy one by the pus in the persons lesions - Agent that caused the disease could pass through the finest filters and could not be observed in a microscope - Caused by filterable agents or viruses 1935 was when Stanley crystallized tobacco mosaic virus and the nature of viruses was demonstrated

Viruses have long been known to cause some cancers in plants and animals, but only recently have some human cancers, including liver cancer and cervical cancer, been shown to be of viral origin. Cancer viruses transform cells by integrating themselves into the DNA of the host cell; the viral genes may override the host's genes, for example, by turning on inappropriate cell division. In fact, viruses that cause cancer in humans have been found to carry altered forms of human genes.

- Some of the genes that, when mutated, lead to cancer— known as oncogenes— stimulate cell division; others, known as tumor suppressor genes, normally function to keep cell division turned off. The new genetic understanding of cancer causation also helps to explain why some families are more susceptible to some kinds of cancer. Since in most cases more than a single mutation is required before a cell is fully malignant, a member of a family that carries one mutation in a gene might need only one additional event to develop a tumor.

The public health approach to primary prevention of cancer is to prevent human exposure to the agents that cause mutation. In the case of ionizing radiation, the danger of which was recognized early, government standards have been developed to protect the population against exposure from various sources such as nuclear power plants, medical and dental x-rays, and radon gas.

- Sunlight, another proven cause of cancer, cannot be regulated: Education in the importance of sunscreen and hats is the favored approach. - Because viruses have only recently been recognized to cause cancer in humans, the public health response to these agents is evolving. - Immunization is one approach: Hepatitis B vaccination is now recommended for all children, not only to prevent acute hepatitis infection but because chronic infection with hepatitis B virus has been shown to lead to liver cancer. - A recently developed vaccine against human papilloma virus has been shown to be effective for the prevention of cervical cancer. It is controversial, however, because it must be given to young girls before they become sexually active. The tars in tobacco smoke are clearly a major cause, and the American Cancer Society estimates that almost one-third of cancer deaths in the United States are due to tobacco use.

The target of HIV is a specific type of white blood cell called the CD4-T lymphocyte, or T4 cell. T4 cells are just one of many components of the complicated immune machinery that is activated when the body recognizes a foreign invader such as a bacterium or a virus. The T4 cell's role is to divide and reproduce itself in response to such an invasion and to attack the invader. In a T4 cell that is infected with HIV, activation of the cell activates the virus also, which then produces thousands of copies of itself in a process that kills the T4 cell.

- T4 cells are a key component of the immune system because, in addition to attacking foreign microbes, they also regulate other components of the immune system, including the cells that produce antibodies, the proteins in the blood that recognize foreign substances. - The course of infection with HIV takes place over a number of years. After being exposed to HIV, a person may or may not notice mild, flu-like symptoms for a few weeks, during which time the virus is present in the blood and body fluids and may be easily transmitted to others by sex or other risky behaviors. - The body's immune system responds as it would to any viral infection, producing specific antibodies that eliminate most of the circulating viruses. The infection then enters a latent period, with the viruses mostly hidden in the DNA of the T4 cells, although a constant battle is taking place between the virus and the immune system. Billions of viruses are made, and millions of T4 cells are destroyed. - During this time, the person is quite healthy and is less likely to transmit the virus than during the early stage of infection (although transmission is still possible). Eventually however, after several years, the immune system begins to lose the struggle, and so many of the T4 cells begin to die that they cannot be replaced rapidly enough. When the number of T4 cells drops below 200 per cubic millimeter of blood, about 20 percent of the normal level, symptoms are likely to begin appearing, and the person is vulnerable to opportunistic infections and certain tumors. At this stage, the person meets the criteria for AIDS, which is defined by the T4 cell count and/ or the presence of opportunistic infections.

shiga toxin gene had "jumped" from one species of bacteria to another while they were both present in human intestines. The resulting strain, called E. coli serotype O157: H7, is now quite common in ground beef, leading public health authorities to recommend or require thorough cooking of hamburgers.

- The "jumping gene" phenomenon has also been found in cholera and diphtheria bacteria, bacterial strains that can be benign or virulent depending on the presence or absence of genes that produce toxins. - Since the finding that E. coli O157: H7 is common in hamburger, it has been discovered to cause illness by a number of other exposures, including unpasteurized apple cider and alfalfa sprouts. In 1999, there was an outbreak in upstate New York among people who had attended a county fair. The bacteria were found in the water supplied to food and drink vendors. It turns out that E. coli O157: H7 is widespread in the intestines of cattle, especially calves, which excrete large quantities of the bacteria in the manure - The manure may contaminate apples fallen from trees or other produce, which if not thoroughly washed before being consumed, may spread the disease to people. At the New York State county fair, the water was contaminated because heavy rain washed manure from the nearby cattle barn into a well. Perhaps the most disturbing development in infectious diseases is the antibiotic resistance among many species of bacteria, a development that leaves physicians powerless against many diseases they thought to be conquered. - In the presence of an antibiotic drug, any mutation that allows a single bacterium to survive confers on it a tremendous selective advantage. That bacterium can then reproduce without competition from other microbes transmitting mutation to offspring and the result is a strain of the bacteria that is resistant to that particular antibiotic. The mutated gene can also "jump" to other bacteria of the same or different species by the exchange of plasmids, small pieces of DNA that can move from one bacterial organism to another. Different mutations may be necessary to confer resistance to different antibiotics. Some bacteria become resistant to many different antibiotics, making it very difficult to treat patients infected with those bacteria.

Dietary salt (sodium chloride) is believed to be a factor in causing some cases of essential hypertension, but sensitivity to salt is variable and is probably determined by genetics. Laboratory studies have found that some strains of rats get high blood pressure when fed large amounts of salt, while rats of other strains do not seem to react to salt. Rats of one sensitive strain tend to have strokes when subjected to salt and stress, while rats of some other strains are unaffected.

- The NHLBI recommends that everyone limit their salt intake to about a teaspoon a day, but the question of whether this measure would reduce blood pressure in the average person is controversial. Some researchers have argued that high dietary salt damages the heart and kidneys even in people with normal blood pressure. - At a population level, it is clear that hypertension has a higher prevalence in groups that consume greater amounts of sodium, and that sodium intake is higher in the United States than in many other countries. The prevalence of hypertension in the United States is high; one in three adults have high blood pressure; about 65 percent of those age 60 or older have it. - Therefore public health experts have noted that reducing the amount of salt in the American diet would be expected to reduce the prevalence of hypertension. They estimate that, for example, if the average systolic blood pressure could be reduced by five points, mortality due to stroke would be reduced by 14 percent. Because Americans tend to get most of their salt from packaged foods and restaurant meals, the American Public Health Association together with an interagency committee coordinated by NHLBI, has recommended that the food industry, including manufacturers and restaurants, reduce sodium in the food supply by 50 percent over the next decade.

In the summer of 1999, the United States first experienced the effects of West Nile virus, which spread rapidly across the country over the next few years.

- The disease was suspected to be St. Louis encephalitis, a mosquito-borne disease that is endemic in the southern United States, and the diagnosis was supported by the patients' reports that they had been outdoors in the evenings during peak mosquito hours. - Soon, however, it became obvious that a great number of dead crows were being found in the New York area, and a veterinarian at the Bronx Zoo reported that there had been unprecedented deaths among the zoo's exotic birds. - West Nile virus was well known in Africa, West Asia, and the Middle East. It is known to be fatal to crows and several other species of birds. It also infects horses. - The virus is easily spread among birds by several species of mosquitoes, some of which also bite humans. - While the infection proves fatal to a small percentage of human victims, it often leaves patients with long-term impairments, including fatigue, weakness, depression, personality changes, gait problems, and memory deficits. Public health professionals fight the virus by educating the public about eliminating standing water where mosquitoes breed, wearing long sleeves, and using repellant. A vaccine is available for horses, and scientists are working on developing a vaccine that will be effective for humans.

It turns out that mutations in DNA can be caused by many different types of agents, including chemicals, viruses, and radiation. Other factors, such as hormones and diet, play a role in determining whether a mutation progresses to the development of a tumor. Hormones, which function in the body to stimulate or inhibit cell growth, may have an enhanced effect on a mutated cell.

- The mechanisms by which dietary factors influence the development of cancer— in addition to the fact that some foods may contain carcinogens, or cancer-causing chemicals— are less well understood. There is some evidence that dietary fiber protects against some cancers, perhaps because it speeds the passage of possible carcinogens through the digestive tract, lessening the likelihood that they will be absorbed. High fat in the diet increases the risk of many forms of cancer, but it is not clear why. Diets high in fruits and vegetables seem to be protective.

The development and licensing of a screening test in 1985 was a major step forward in the fight against HIV.

- The test measures antibodies to the virus, which begin to appear 3 to 6 weeks after the original infection. The test is used for three purposes: diagnosing individuals at risk to determine whether they are infected so that they may be appropriately counseled and, if necessary, treated; monitoring the spread of HIV in various populations via epidemiologic studies; and screening donated blood or organs to ensure that they do not transmit HIV to a recipient of a transfusion or transplant. - A major drawback of the antibody screening test is the absence of antibodies in the blood during the initial 3- to 6-week period after infection. This "window" of nondetectability may give newly infected people a false sense of security. Tests that directly measure a virus in the blood have contributed a great deal to understanding the biomedical basis of HIV infection. Measurement of "viral load"— the concentration of viruses in the blood— is a valuable tool for evaluating the effectiveness of therapeutic drugs.

Ebola

- The virus was spreading silently into African cities, another viral illness broke out with much more dramatic effect in Zaire and Sudan. Symptoms caused by the previously unidentified Ebola virus include fever, vomiting and diarrhea, and severe bleeding from various bodily orifices. Several hundred people became ill from the disease, and up to 90 percent of its victims died. - The disease spread rapidly from person to person, affecting especially family members and hospital workers who had cared for patients. Investigators from the CDC and WHO identified the virus and helped devise measures, including quarantine, to limit the spread of the disease, which eventually disappeared. The Ebola virus broke out again in Zaire in the summer of 1995, killing 244 people before it again seemed to vanish. - The Ebola virus broke out again in Zaire in the summer of 1995, killing 244 people before it again seemed to vanish. 23 Since then, there have been repeated outbreaks in West and Central Africa. According to CDC data, more than 800 Africans died of Ebola between 1996 and early 2013. - Ebola virus affects monkeys and apes as well as humans and sometimes monkeys - In 1989, a large number of monkeys imported from the Philippines died of the viral infection at a primate quarantine facility in Reston, Virginia. In that episode, which served as the basis for Richard Preston's book, The Hot Zone, several laboratory workers were exposed to the virus, which fortunately turned out to be a strain that did not cause illness in humans. - There are indications that, like HIV, Ebola may spread to humans when they handle the carcasses of apes used for food. Unlike HIV, the Ebola virus kills the apes it infects, leading to significant declines in populations of gorillas and chimpanzees; outbreaks in humans have been preceded by the discovery of dead animals near villages where the outbreaks occur. There is now concern that Ebola may be pushing West African gorillas to extinction.

Diabetes is a deficiency in the body's ability to metabolize sugar, a function that is normally controlled by the hormone insulin.

- There are two major forms of diabetes: Type 1 diabetes, which usually has its onset in childhood, is caused by a failure of the insulin-producing cells of the pancreas; type 2 diabetes, more common with increasing age, is a more complex mix of impaired insulin production and resistance to the hormone's action. Both forms of diabetes are significantly affected by genetics. Research on the causes of diabetes has thus far yielded very little information on how type 1 diabetes could be prevented. Type 2 is closely correlated with obesity, and is largely preventable with proper diet and exercise. However, public health has not been very successful in persuading most people to adopt such healthy behaviors, which could prevent a number of other chronic diseases as well.

Bacteria is a single-celled organism that can reproduce outside the body while viruses are not complete cells

- Viruses are complexes of nucleic acids and protein that lack the ability to reproduce themselves - Viruses impact both animal and plant cells such as tobacco mosaic virus impacts bacteria and tobacco - Viruses can survive in extreme conditions with alcohol and drying in a vacuum to be active again when they are injected in a living cell - Viruses reproduce themselves by taking control of the cell's machinery and often killing the cell in the process - The human diseases caused by viruses include smallpox, yellow fever, polio, hepatitis, influenza, measles, rabies, and AIDS, as well as the common cold. Human diseases can also be caused by protozoa or a single cell-celled animals that live as parasites in the human body - Malaria, spread by mosquitoes; - cryptospiridiosis, which caused the Milwaukee diarrhea epidemic - giardiasis, also known as "beaver fever" are examples of protozoal diseases Other parasites, such as roundworms, tapeworms, hookworms, and pinworms, are the most common source of human infection in the world. Except for pinworms, they are not common in the United States today.

Smallpox

- While constant vigilance is required to protect people from rabies because wild animals serve as a reservoir of the disease, some pathogenic viruses, including measles and polio, have no nonhuman reservoir. - The universal immunization against these diseases could eliminate the measles and polio viruses from the earth. This has been achieved with smallpox, one of public health's greatest victories. - Smallpox was a particularly feared disease that is believed to have first emerged in Asia about the time of Christ and tended to spread in major epidemics that claimed millions of lives in China, Japan, the Roman Empire, Europe, and the Americas. - It was highly contagious, spread by aerosol or by touch. The concept of vaccination originated with smallpox: the observation that survivors of the disease were immune to future infection inspired the idea that people could be protected against serious illness by inoculating them with small amounts of infected matter from a person suffering a mild case. British physician Edward Jenner— inspired by the observation that milkmaids appeared to be immune to smallpox— proved that inoculation with cowpox matter, which was harmless to humans, provided immunity against smallpox.

Poliovirus, like smallpox virus, infects human beings only, and polio similarly has the potential to be eradicated. In 1988, at a time when 350,000 children were being paralyzed each year, WHO set a goal of eradicating polio by the year 2000

- polio has been essentially eliminated from the Western Hemisphere, Europe, Southeast Asia, and the Western Pacific, and by 1999, annual polio cases were reduced by 99 percent worldwide. - Only three countries continue to have endemic polio— Nigeria, Pakistan, and Afghanistan— but eradication from these countries has proven extremely difficult. Rumors spread in 2003 among Muslims, especially in Nigeria, that the polio vaccine had been deliberately contaminated to cause AIDS or infertility. - Several Nigerian states halted vaccinations, the number of cases in Nigeria jumped to 800 in 2004, and the virus spread to several other African countries that had previously been polio free. Under pressure from WHO, Nigeria resumed polio immunizations the following year. There are several reasons why polio is proving more difficult to eradicate than smallpox. Unlike smallpox, there are many "invisible" cases of polio, in which children may be infected, able to spread the virus by the fecal-oral route but not show symptoms.

Another drawback of people's fear of vaccines is that pharmaceutical companies have become reluctant to invest in developing them

- serious health problem suffered by their children leads them to sue the company that made the vaccine. This experience, together with the fact that prices that can be charged for vaccines tend to be low, has caused many companies to drop vaccine production altogether. - While immunization is considered the most effective intervention for preventing disease and promoting health, it is not clear that even the current vaccines will continue to be available. The example of the former Soviet Union stands as a warning to us. Diphtheria is virtually unknown in the West now, but in the 1980s, when the public health system in Russia was in chaos and immunizations stopped, the disease surged, with 200,000 cases and 5000 deaths there. Public health in the United States can celebrate success in the fight against many common diseases. In 2007, the CDC reported that death rates for 13 infectious diseases were at all-time lows; for nine of them, including whooping cough, polio, and diphtheria, deaths and hospitalizations declined by more than 90 percent sin

"The principal risk behavior for acquiring TB infection is breathing," as one expert says.

. - When tuberculosis bacilli are inhaled by a healthy person, they do not usually cause illness in the short term. Most often, the immune system responds by killing off most of the bacilli and walling off the rest into small, calcified lesions in the lungs called tubercles, which remain dormant indefinitely. For reasons that are not well understood, probably having to do with individual immune system variations, a small percentage of people develop active disease soon after exposure; others may harbor the latent infection for years before it becomes active, if ever. - Infected people have a 10 percent lifetime risk of developing an active case. The risk for people who are HIV positive is much higher: up to 50 percent. - Most cases of active tuberculosis are characterized by growth of the bacilli in the lungs, causing breakdown of the tissue and the major symptom— coughing— which releases the infectious agents into the air. However, the development of multidrug resistance (MDR), in some strains of the bacilli, has meant that the disease is much more difficult and expensive to treat, and the mortality rate is much higher. The tuberculosis bacillus is a particularly difficult pathogen to deal with because it grows slowly and because diagnostic testing can take several weeks. Once the disease is diagnosed, even the most potent antibiotic must be taken for several months to wipe out the pathogens. Patients commonly begin to feel better after 2 to 4 weeks of taking an effective prescribed drug and, if they stop taking the medication at that point, they may relapse with a drug-resistant strain.

Five types of influenza surveillance

1. Viral Surveillance: works with specific labs such as university of Florida health care service, gets clinicians to send swabs to CDC and tested to see if they have flu and what subtype they have Colors represent different types of flu virus Purple: 2009, H3N2 Red- influenza A with H3 which is a hemogluten type Yellow: influenza A without subtyping Green: influenza B which includes lots of different types of influenza 2. Influenza like-illness monitoring: track doctors diagnosis and how many people they see with influenza like illnesses 5 or 6 percent one out of 25 has influenza like illness Underline: One of 100 has influenza like illness In December of January: have a lot more influenza like illness and now reduced 2003- Came a bit sooner in December 2009- H1N1 early Normal flu graph 3. Mortality Surveillance: Mortality: percentages of deaths reported with pneumonia Seasonal: expect people to have flu at certain times 10 percent of all deaths reported due to pneumonia influenza More deaths in December and January Deaths is 5-10 4. Summary of geographic spread of influenza Is flu having a local spread, regional, or widespread?Week ending in January 26, 2013 in the US reported by state and territorial- most country in widespread flu epidemic

Costs of Chronic Diseases

84% of all health care spending in 2006 was for the 50% of population who had one or more chronic diseases and conditions Total cost of heart disease and stroke in 2010 estimated to be $315.4 billion Diabetes is $245 billion in 2010 Cancer care cost $157 billion in 2012 Economic cost due to smoking in 2009-2012 is more than $289 billion a year Economic cost of drinking too much alcohol $223.5 billion in 2006 Losses in workplace productivity, health care expenses including direct medical costs, crimes related to excessive drinking

Characteristics of case control

A single point of observation • Unit of observation and analysis are the individual • Participants are defined by whether or not have disease or outcome of interest • Exposure is determined retrospectively Example of case control: Table look and see high percentage with coronary heart disease who smoke cigarettes

Sources of Cases

A tumor registry public health reports or vital statistics bureau may provide a complete listing of all diagnosed cases • Who are we missing? • Medical facilities may , be a source of cases, but not always incident cases. People who may not be captured in larger registries Why incident cases? Need to know new number of cases of disease outcomes What bias may arise from finding cases at a specialty clinic? Incident cases for people newly diagnosed with HIV: sample from men and women getting help services at clinic , we miss those who do not have access to those resources and may actually those most interested and they represent arrange of socioeconomic risk factors that we can attribute to increased risk or give us a better characteristic profile for those at high risk to HIV

Relative Risk Frequency

A: was exposed and developed a disease B: exposed but did not develop a disease C: was not exposed but still had the disease D: was not exposed and did not develop the disease Relative risk: number of people in exposed group so amount of people who were in new cases Relative Risk= a/a+b divided by c/c+d rate of risk in exposed group/ rate of risk in unexposed group

Priority interventions

Accelerated tobacco control Salt reduction Promotion of healthy diets and physical activity Reduction of harmful alcohol consumption Access to essential drugs and technologies Clinical services- highly cost effective in low resourced countries and will reduce the chances of premature deaths All the other 4 are population white Feasibility of priority intervention depends on factors 1. Politics 2. Resource availability 3. Health system capacity 4. Community support 5. Power of commercial interest 6. Experiences of other countries International commitments and support

Leading causes of death, why are they important?

Account for almost half of all deaths Most are preventable For example smoking is preventable and eating an unhealthy diet is preventable Most are premature Lot of people die due to heart failure or cardiovascular diseases at a much younger rate than actual should live Most are caused by individual behavior Targets for public health intervention

Cross Selectional Advantages and Disadvantages

Advantages • Quick, simple, inexpensive • Good approach for generating hypotheses and Good approach for generating hypotheses and estimating prevalence/disease burden Disadvantages • Do not provide incidence data (usually) • Imp practical for low prevalence diseases • Cannot determine temporality of exposure and disease (cannot prove causality)

When epidemiologists are called on to investigate an outbreak of an infectious disease, what is the first thing they must do?

Agree on a case definition

Example of Ecological Study

Air pollution and asthma emergency room visits • Air quality samples are taken throughout cities in the US and hospital records are available for the US and hospital records are available for the reasons for ER visits • One days of very poor air quality in Los Angeles ER, visits for people reporting asthma attacks increase significantly Problems with Example: Air quality samples may not reflect quality of air where individuals who visit the ER live/work • Poor air quality may occur in tandem with other Poor air quality may occur in tandem with other events that trigger asthma attacks (i.e. season) • On poor air quality days people with asthma may stay inside, so it is the indoor rather than outdoor air quality that is causing their symptom

Smoking being the major cause of lung cancer, smoking increases the risk of cancer in many other organs, including the mouth, lips, nose and sinuses, larynx, pharynx, esophagus, stomach, pancreas, kidney, bladder, uterus, cervix, colon and rectum, ovary, and some kinds of leukemia.

Although Americans are greatly concerned about the possibility of cancer-causing chemicals in their food, water, or air, little is known about whether these sources contribute significantly to the number of cases diagnosed each year. Most industrial chemicals have not been tested for carcinogenicity. Chemicals added to food, however, must be tested. The testing of chemicals for carcinogenicity in humans is fraught with difficulties. The standard, most definitive approach is a controlled experiment in which a large group of rats, mice, or guinea pigs is fed a diet containing the suspect chemical over their whole lifetime— about two years for these animals— and the incidence of tumors in this group is compared with that in an equivalent group of animals that did not receive the chemical. - If the exposed animals have more tumors than the unexposed, the chemical is labeled a carcinogen. Aside from the potential frustration of the experiment by some unpredictable factor— for example, an outbreak of mouse flu that kills off all the animals after the first year, necessitating a new start— there are many reasons why this approach may not accurately predict carcinogenicity in humans. Differences in metabolism between mouse and human sometimes mean differences in carcinogenicity of a chemical in the two species; or the dose of the chemical necessary to produce a detectable increase in tumors may be so high that it disrupts the animals' metabolism, making the results meaningless.

Eosinophilia- Myalgia Syndrome:

Although infectious agents are usually suspected first in any outbreak of a new disease, epidemiologists must also consider exposure to a toxic substance as an alternative cause. Physicians and epidemiologists found this to be the case in a puzzling outbreak first reported in New Mexico. In October 1989, several Santa Fe doctors were comparing notes on three patients suffering from a novel condition involving fatigue, debilitating muscle pain, rashes, and shortness of breath. Blood tests on all three had revealed very high counts of white blood cells called eosinophils. However, they were struck by the fact that all three patients, when questioned about drugs or medications they were taking, had mentioned a health food supplement called L-tryptophan. L-tryptophan is a "natural" substance, a component of proteins, that had been publicized as a treatment for insomnia, depression, and premenstrual symptoms. A team of health department investigators interviewed these 12 people and found that they all had used L-tryptophan. They also interviewed 24 people of the same age and sex as the patients who lived in the same neighborhoods— a control group— and found that only two had taken the supplement. This strongly suggested that there was a link between L-tryptophan exposure and the illness. Why had this natural substance caused such severe consequences? L-tryptophan is an amino acid, present in many foods including meat, fish, poultry, and cheese. It is also added to infant formulas, special dietary foods, and intravenous and oral solutions administered to patients with special medical needs. No cases of EMS had been reported from these products. The fact that many people took the supplements with no apparent harm suggests that individual variations in susceptibility may exist. To many public health experts, the EMS epidemic of 1989 resembled an illness with similar symptoms that affected some 20,000 people in Spain in 1981, killing more than 300 of them within a few months. An infectious agent had first been suspected, but epidemiologists noted an odd geographical distribution of the outbreak. Patients lived either in a localized area south of Madrid or in a corridor along a road north of the city. The epidemiologists found that the affected households had bought oil for cooking from itinerant salespeople, who were illegally selling oil that had been manufactured for industrial use. They now suspect that a range of chemicals, even at very low concentrations, may induce autoimmune responses in susceptible people, causing the body's immune system to attack its own tissues. Such outbreaks caused by toxic contamination of foods and drugs may be much more common than is generally recognized

Lung cancer

An exception was the link between smoking and lung cancer. Mortality from lung cancer had been increasing dramatically since the 1930s. Because it was logical to suppose that the cause might be something that was inhaled, the two main hypotheses proposed to explain this increase were tobacco smoking and air pollution, both having increased during the same period that lung cancer was rising. In late 1950 and early 1952, two major epidemiologic studies were started that convincingly established a link between lung cancer and tobacco smoking. The British epidemiologists Richard Doll and A. Bradford Hill sent out a questionnaire to all physicians in the United Kingdom, asking whether they were smokers, past smokers, or nonsmokers. Smokers and ex-smokers were asked to provide additional information on their age at starting to smoke and the amount of tobacco smoked, and ex-smokers were asked when they had quit smoking. First, the death rate from lung cancer was about 20 times higher among smokers than among nonsmokers, increasing as the amount smoked increased. Second, the death rate among ex-smokers was lower than that of smokers and declined as the length of time increased since the doctor had quit smoking. Third, the contrast in lung cancer mortality between smokers and nonsmokers was the same whether the doctors lived in rural or urban areas. Therefore, the difference could not be attributed to air pollution. Fourth, deaths from heart attacks were also significantly higher among heavy smokers aged 35 to 54 than among nonsmokers. A similar study on a much larger group of people was conducted in the United States by epidemiologists E. Cuyler Hammond and Daniel Horn. They obtained smoking histories from almost 188,000 men aged 50 to 69 and followed them over a period of 3 years and 8 months. For all the study participants who died, they obtained the cause of death from death certificates. Their findings confirmed and extended the results of the Doll and Hill study of British doctors. First, cigarette smokers were more than ten times more likely to die of lung cancer than nonsmokers. Second, cigarette smokers were about five times more likely to die of cancer of the lip, tongue, mouth, pharynx, larynx, and esophagus as nonsmokers. Several other types of cancer were also more common among smokers. Third, heavy smokers (two or more were 2.4 times more likely to die of heart disease than nonsmokers. The British study continued until 1971, tracking all the doctors for 20 years, by which time about 33 percent of them had died. The longer period of observation confirmed the results obtained earlier. An interesting finding was that many physicians reacted to the earlier reports by quitting smoking. By 1971, the average number of cigarettes smoked per day by the physicians in the study was less than half what it had been in 1951, and as a result, lung cancer became relatively less common as a cause of death in this group. The Framingham Study and the two lung cancer studies are examples of prospective cohort studies, following large numbers of people over extended periods of time. These are considered among the most reliable kinds of epidemiologic studies for investigating causes of chronic diseases.

The group A strain, which produces a potent toxin, was prevalent in the early part of the 20th century, when it caused scarlet fever, frequently fatal in children, and rheumatic fever, which often caused damage to the heart.

Another bacterium that has recently become more deadly is Escherichia coli, which is normally present without ill effect in the human digestive tract. - In 1993, the new threat gained national attention when a number of people became severely ill after eating hamburgers at a Jack in the Box restaurant in Seattle, and four children died of kidney failure. - The culprit was found to be a new strain of E. coli, which had acquired a gene for shiga toxin from a dysentery-causing bacterium. The toxin, against which there is no treatment, causes kidney failure, especially in children and the elderly

Threat of bioterrorism

Anthrax: nail, someone spreading it in letter, postal workers died Smallpox: eliminated but still some stocks of vaccines, consider it to be the worst infectious disease (stop getting vaccinated for it) Multidisciplinary approach: not everyone agrees

Chronic Disease Statistics

As of 2012, about half of all adults-117 million people-have one or more chronic health conditions One of four adults has two or more chronic health condition 7 out of top 10 causes of death in 2010 were chronic diseases Two chronic diseases-heart disease and cancer together accounted for nearly 48% of all deaths Arthritis-most common cause of disability Out of 53 million people with arthritis diagnosis, 22 million have trouble with their daily activities Diabetes. Leading cause of kidney failure, lower limb amputations (without an injury), new cases of blindness among adults 1990, CDC Leading causes were not actual causes of death but were the diagnosis done at the time of death Disease actually resulted from inborn and external factors Scientists compiled a list of preventable behaviors and conditions that resulted in a disease that caused the mortality Actual causes of death are defined as lifestyle and behavioral factors such as smoking and physical inactivity that contribute to the nations leading killers including heart disease, cancer, and stroke

The Ten Essential Public Health Services

Assessment: 1. Monitor health status to identify community health problems 2. Diagnose and investigate health problems and health hazards in the community Policy Development: 3. Inform, educate, and empower people about health issues 4. Mobilize community partnerships to identify and solve health problems 5. Develop policies and plans that support individual and community health efforts Assurance: 6. Enforce laws and regulations that protect health and ensure safety 7. Link people to needed personal health services and assure the provision of health care when otherwise unavailable 8. Assure a competent public health and personal healthcare workplace 9. Evaluate effectiveness, accessibility, and quality of personal and population-based health services Serving all functions: Research for new insights and innovative solutions to health problems

Infectious diseases are spread through a variety of routes including directly from person to another or indirectly through by way of water, food, or vectors as insects or animals

Bacteria and viruses that cause respiratory infections, including colds, influenza, and tuberculosis, are transmitted through the air on aerosols, water droplets produced when an infected person coughs or sneezes - Can be transmitted from an infected person to objects he or she touches, such as doorknobs, utensils or towels to be picked up by the next person to touch the contaminated object and transferred by hand to nose - The early European settlers made use of this route of transmission to inflict a primitive form of germ warfare on the Native American people, giving them blankets that had been used by patients suffering from smallpox. - The disease decimated Native American populations because they had no immunity to the virus. Gastrointestinal infections such as cholera, cryptospiridiosis, and diphtheria are generally spread by the fecal- oral route, by which fecal matter from an infected person reaches the mouth of an uninfected person. - This may occur as a result of poor personal hygiene or by contamination of drinking water because of inadequate sanitary systems. Vector-borne diseases, including malaria, yellow fever, and West Nile encephalitis, generally use a more complex route from one person to another, most often through an insect

Temporality problem

Because exposure and outcome are assessed at the same time in cross-sectional studies, it can be hard to determine which came first • Called temporal sequence - Problem with temporality : because exposure and outcome are assessed at the same time in cross-selection studies (difficult to assess the causal relationship) it can be hard to determine what came first known as a temporal sequence We do not know which came first, do opiates cause people to fall or are people fell and now they are on medication

Biomedical sciences

Biomedical sciences: provide epidemiologists a clear understanding of the disease or infection causing agents in the environment, control of infections was a major focus in 19th century and biomedical sciences have been extremely successful in identifying and controlling several life disease threatening agents in environment by increasing life expectancy in individuals

Continuing PublicHealth Challenges

Bioterrorism: happenings of 2001, made the nation in shock and feeling unsafe, several threats of anthrax after the September attack confounded the fears and feelings of insecurity among people Lifestyle and behavioral changes: in order to protect themselves from chronic diseases, until people understand prevention it is difficult to bring about lifestyle changes (these issues are compounded by the funding cuts in public health due to economic recession and changes of priority of government based on ruling party preference) Bioterrorism • Lifestyle and behavior changes • Chronic diseases prevention and control • Emerging infectious diseases • Funding cuts

Cancer

Cancer has proven much more difficult to understand than cardiovascular disease, in part because it has so many different manifestations. It is sometimes said that cancer is not one disease, but 100 diseases. In many ways, breast cancer is different from lung cancer, which is different from leukemia. What all cancers have in common is that they arise when the activities of a cell are transformed and the cell begins to grow out of control.

Epidemiology and other causes of chronic diseases:

Cancer, heart disease, and other diseases of aging do not have single causes. They tend to develop over a period of time, are often chronic and disabling rather than rapidly fatal, and cannot be prevented or cured by any vaccine or "magic bullet." The best hope for protecting the public against these diseases is to learn how to prevent them, or at least how to delay their onset. Prevention, however, requires an understanding of the cause or causes of a disease and the factors that influence how it progresses. Epidemiology has made major contributions to the current understanding of the causes of heart disease and some cancers and what can be done to prevent them. Most chronic diseases cannot be attributed to a single cause There may be many different factors that play a part in causing a disease, factors that epidemiologists call "risk factors." Epidemiologists must determine which of a person's many experiences over the previous decades are relevant, and what significant exposures might have occurred 10 or 20 years ago that may have increased the person's risk of developing the disease today.

Case Control Study

Case Control Studies: looks at people who are already ill and investigate backwards to determine the exposures (retrospective study) (select people with heart disease vs without heart diseases and retrospectively study their exposures) More efficient than cohort studies, focusses on smaller number of people, can be completed relatively quickly Strength of association between exposure and disease - odds ratio (relative risk in cohort studies) Odds ratio= exposed/non exposed in case group divided by exposed/non exposed in control group We go backwards and do a lot of questioning, home visit, talk to the family or talk to the patient to determine the exposures (questions like what did you do, what was your lifestyle, what happened, how did you develop the disease) In a case-control study, cases— people who have the disease— are compared with controls, healthy individuals chosen to match the cases as much as possible in age, sex, and other factors that might be relevant to the disease. The investigator asks all participants the same questions concerning the extent of their exposure to factors hypothesized to have caused the disease.. An important case-control study conducted in the mid-1980s sought the cause of Reye's syndrome, a deadly disease of children that occurred a few weeks after a child had recovered from a viral infection such as chicken pox.- the hypothesis that the development of Reye's syndrome was linked to medications the child was given during the viral illness. Also another study that looked at the cause of breast cancer, the results indicate that use of oral contraceptives did increase the risk of developing breast cancer for women aged 45 and under and that the risk increases with longer exposure. As a result of this study, the FDA required drug producers to put warning labels on aspirin containers and told pediatricians to advise parents to give their children acetaminophen (Tylenol) rather than aspirin to treat infections. Case-control studies estimate the strength of the association between exposure and disease by calculating an odds ratio which is an estimate of what the relative risk would be if a cohort study had been done. A smaller odds ratio (or relative risk) leads to a much less certain conclusion. Retrospective: look at why certain people developed a heart disease and some people did not

History of Epidemiology

Cholera strikes London in 1848 John Snow, a British anesthesiologist noticed certain key issues Water supply from same two companies: Southwark & Vauxhall and Lambeth Company Formulated the hypothesis: cholera spreads through polluted water 1853-severe outbreak concentrated in Broad Street area of London 'shoe-leather epidemiology' He looked at number of houses, number of deaths from cholera and deaths per 10,000 houses During period of 1848-1849 Several theories during that time that was predicting the cause of disease ONE OF THE MOST PROMINENT THEORIES DURING THE TIME WAS THE MIASMIC THEORY which says that bad air is the cause of all the diseases so people who inhale air get the disease Dr. Kar who was the registry general at that time in London believed in bad air or the Miasmic theory, tried to formulate interventions based on this theory However, John Snow at the time believed that something else was the cause of the disease and he also believed that the disease was being caused due to polluted water consumer by people but he did not have enough evidence to prove this theory John Snow was the first man who compiled disease data and what he did is known as the shoe-leather epidemiology where they go to the site and go around to each household talking to individuals to try to investigate and find the cause of the disease Concerned with cholera epidemic in London of 1848, Snow noticed that death rates were High in parts of the city where the water supply was supplied by 2 private Companies both from Thomas river

Biomedical Basis of Chronic Diseases:

Chronic degenerative diseases, especially heart disease and cancer, are now the leading causes of death in the United States. - Cancer is the leading cause of death among Americans aged 45-65 - Prevention of disease usually requires some understanding of the cause, a requirement that is generally much more difficult to fulfill for chronic diseases than for infectious ones. There is no single pathogen that causes cancer or heart disease, nor is there one for arthritis, diabetes, or Alzheimer's disease. - In most cases, chronic diseases have multiple causes, making it more difficult for scientists to recognize significant risk factors and establish preventive measures. Chronic diseases develop over long periods of time- the gradual onset allows for a period of early detection

Evolution of the Global Burden of Disease, 2002 to 2030

Chronic disease evolved: More infectious disease in early years and period of time conquered infectious diseases and now have chronic disease as the most important global burden of disease Except for south Africa, all other countries have seen or will see a decline in infectious diseases and increase in chronic diseases in the next few decades

What are chronic diseases?

Chronic disease is a long lasting condition that can be controlled but not cured (WHO) Have multiple causes- difficult to recognize risk factors and establish preventive measures Tend to develop over long periods of time (gradual onset - early detection) Leading cause of death or disability in US Covers 75% of health care costs 4 main types: Cardiovascular diseases Cancers Chronic respiratory diseases Diabetes Mental illness Alzheimer's disease Arthritis (LAST ARE APART)

Water supply issue

Clearly shows which water supply is clearly creating the problem Dr. Snow actually went to remove the hand pump in order to prevent people from drinking from that pump ( no more new incidences of cholera being reported) Broad street pump in London: one of the important landmark of the city The rate of deaths was 8.5 times higher in houses supplied by the Southwark and Vauxhall Company than those supplied by the Lambeth Company. Snow would not have been able to test his hypothesis without the data on cholera deaths, which had been collected by the British government as part of a system for routine compilation of births and deaths, including cause of death, since 1839. Now, the governments of all developed countries collect data on births, deaths, and other vital statistics. These data are often used for epidemiologic studies. Because it is preferable to recognize that an epidemic is occurring before many people start dying, governments also use a system called epidemiologic surveillance, requiring that certain "notifiable" diseases be reported as soon as they are diagnosed. In the United States, approximately 60 diseases have been identified by law as notifiable at the federal level, including, for example, tuberculosis, hepatitis, measles, and syphilis. While the surveillance system was created to control the spread of known diseases, the established network of reporting can facilitate the recognition that a new disease may be emerging. The first step in recognizing that a community is facing a new problem is usually a report to the local or state health department or the CDC by a perceptive physician who notices something unusual that he or she thinks should be investigated further. Epidemiologic surveillance is a major line of defense in protecting the public against disease. It is the warning system that alerts the community that something is wrong, that a gap has opened in the protective bulwark against preventable disease or that a new disease has appeared on the horizon. The sooner the surveillance system kicks in, the sooner action can be taken to stop the epidemic. After the epidemic is recognized, all the resources of the community— local, state, or national— can be mobilized to prevent the disease's spread. Whether it uses vaccination campaigns against measles, isolation of hepatitis-infected food workers, new regulations on air conditioning systems, or recall of contaminated food or drugs, the government must act to protect the health of the public.

Which of the following is a common source of error in a large cohort study?

Confounding variables

Sources of Controls

Controls must be people who do not have the outcome of interest and also people who have not been exposed to the pathogen or risk factor being exposed Population-based controls (random sample) • Likely to be the most representative • People in the same geographic region • Driver's license list; voting lists, random digit dialing Patients from the same hospital as the cases • Relatives or friends of cases

Cost-Benefit Analysis

Cost- Benefit Analysis Cost- benefit analysis weighs the estimated cost of implementing a policy against the estimated benefit, usually in monetary terms. In the benzene example discussed previously, the industry argued that setting a low exposure limit would be very expensive and that the benefit in lives saved would be small. Part of the difficulty in conducting such an analysis is the determination of what monetary value to place on a life saved. In other situations, the analysis provides a clearer justification for a program. For example, an analysis of the costs and benefits of immunizing children against measles, mumps, and rubella— comparing the costs of the immunization program with the costs of caring for the thousands of patients whose disease would not have been prevented if no immunizations had been done— yielded a 13 to 1 ratio of benefits to costs. Another evaluation technique is cost-effectiveness analysis, which compares the efficiency of different methods of attaining the same objective. For example, it may be so expensive to prevent heart attacks in healthy men by prescribing cholesterol-lowering drugs that a cost-effectiveness cost-effectiveness analysis would conclude that it is cheaper to skip the drugs and provide cardiac care for the men who do suffer an attack. Cost- benefit analysis and cost-effectiveness analysis "cannot serve as the sole or primary determinant of a health care decision," according to a congressional report, but the process of identifying and considering all the relevant costs and benefits can improve decision making.

Disease Frequency

Count number of people with disease and relate Count number of people with disease and relate to the population at risk (PAR) • PAR (denominator) may be total population or PAR (denominator) may be total population or exposed population, or one gender or age group; often comes from census • Two ways to measure frequency: • Incidence - number of new cases • Prevalence - number of existing cases • Incidence is used for studying causes of disease If causes or risk factors increase incidence and If causes or risk factors increase, incidence and prevalence increase • If ability to diagnose increases incidence and If ability to diagnose increases, incidence and prevalence increase • Prevalence depends on incidence and prognosis

Crude Mortality vs. Adjusted Mortality

Crude Mortality rate Vs. Adjusted Mortality rate Death rates are adjusted according to population to make it more comparable. Crude Mortality rate of FL higher than Alaska, however age-adjusted mortality rates of Alaska is higher than Florida! Could be adjusted to race, gender and so on. Life Expectancy: The average number of years remaining to people at a particular age Years of Potential Life Lost: Measure of premature mortality. Help to enable people to live out their natural life span with a minimum of illness and disability Florida has a large elderly popular is why its crude mortality rate is higher in Florida than Alaska, once we adjust the mortality rate and make it comparable, we find that Alaska has a higher age adjusted mortality rate How long a person lives in a certain are, lower developed countries have a smaller life expectancy rate compared to developed countries like INDIA for example compared to US When people lose their life like young people due to accidents or sudden diseases, that's when you calculate years of potential life loss

Step 1: define the disease

Death is easy to determine Death is easy to determine - death certificates death certificates have cause of death • Some diseases need blood tests or stool Some diseases need blood tests or stool cultures to verify diagnosis • Some diseases are hard to define Some diseases are hard to define - e g EMS e.g. EMS, SARS • Sometimes definition changes as more is learned - e.g. AIDS • Other health outcomes - injuries, risk factors

International comparisons of cancer mortality suggest that which of the following factors accounts for differences among countries in colon and rectum cancer:

Diet

Poor Diet

Dietary fat Sedentary behavior Obesity Dietary salt Leading to heart disease, stroke, several forms of cancer and diabetes 22% of death due to this cause Public Health Programs: sidewalks, university gyms and other activities Known leading cause of chronic diseases

Too much alcohol

Drinking too much alcohol causes 88,000 deaths each year, more than half due to binge drinking About 38 million US adults report binge drinking an average of 4 times a month- with an average of 8 drinks per binge Most binge drinkers are NOT alcohol dependent

Which kind of loss to follow-up would not affect the internal validity of the clinical trial?

Dropping out of the study due to miscellaneous issues, like pregnancy, hit by a car, or bereavement

Stating an association at the individual level based on data at the group or population level. What is it called?

Ecological Fallacy

Promoting health behaviors

Education is called awareness creation For instance smoking is bad, recommend dietary elements, sex education, physician recommends walk 10,000 steps Mass advertising Direct Indirect Social norms approach Doctor's office visit counseling Regulation Passing and enforcing laws - prohibitions! To retrain people from harming themselves and others Prohibition on selling alcohol or certain drugs Laws under murder assault, traffic regulation, restrictions on drug/alcohol/tobacco 18th amendment which banned alcohol was effective in reducing diseases caused by alcohol to some extent so prohibition does work to some extent but not always

Randomization

Eligible and willing participants are assigned to exposure status independent of other factors • Each participant's assignment is unpredictable (like a coin toss) After we established person is eligible, will go through informed consent to understand the conditions Experimental studies: one study to receive intervention and other receives placebo Have a 50/50 chance for either condition, has to be explained because some may feel that it's a reasonable chance they want to take while others don't want to given their condition So an assignment to a particular control group or experimental group is completely unpredictable

Factors that lead to emergence of infectious diseases

Emerging infections can be old infections that come into new populations or ones we have never seen before Ecologic: interaction of people with environment, animals with people, people with vectors, new urban areas grow that use to be not urban, will see the humans against pathogens and see disturbances of ecology such as killing off wolves that previously killed the mice that carried vectors International travel: more people traveling, more emergence of infections, international travel can be involved with mosquitos Contacts with foods: lots of outbreaks associated with food, animals can be vectors of the pathogens themselves to humans or they could be carrying vectors such as ticks to spread disease Health care systems: have seen lots of great moments due to antibiotics, a lot seen with sick and vulnerable people susceptible to pathogens on their body Ticks and mosquitos are responsible for transmission of lots of pathogens and they can transmit pathogens to other animal vectors such as animal- animal, person-person and create new illnesses Hepatitis C can be associated with injection usage

Concepts of Epidemiology

Endemic: defined as the habitual presence of a disease within a given geographical area/ usual occurrence of a given disease within such an area (eg: avian flu, SARS) Habitual presence of disease: Diseases present often in certain geographical areas: avian flu, SARS so they are called endemic in those geographical areas Epidemic: defined as the occurrence in a community or region of a group of illnesses of similar nature, clearly in excess of normal expectancy derived from a common or from a propagated source Clearly in excess of normal expectancy: Sudden occurrence coming from a common source such as polluted water, infected food product from shelf, or food you ate out can cause epidemics Pandemic: refers to a worldwide epidemic Pandemic: one of the most common worldwide epidemics are HIV/AIDS because it has affected people all over the world and all across different populations

Environmental health sciences

Environmental health sciences: our environment is getting polluted by agents and gases everyday, a clear understanding of the various disease causing agents and its spread through air, water, and food is necessary to control them Though it is not a separate science, environmental specialists work very closely with biomedical sciences in order to identify and understand the channels of transmission for various contagious disease causing organisms in the environment

Definition of Epidemiology

Epidemiology is the study of the distribution and Epidemiology is the study of the distribution and determinants of disease frequency in human populations ◊ Have surveillance: which monitors disease occurrence ◊ Epidemiological research: harvest valid and precise information about the causes, preventions, and treatments for disease (experimental studies, observational studies such as cohort and case control studies) Disease: refers to a broad array of health states (events that include injuries, deaths, and disabilities)

Human population

Epidemiology observes humans in contrast to Epidemiology observes humans, in contrast to biomedical sciences, which can do experiments on laboratory animals ◊ With experimental issues also known as trials, we investigate some factor or agent ◊ Sometimes experimental studies are infeasible due to high costs and ethical issues (so some research is done doing observational studies) Observational studies: considered natural because the investigator lets nature take its course, take advantage that people are exposed to healthy substances (studies provide exposures that occur in natural settings)- do not suffer from ethical and feasible issues of experimental studies

Epidemiology

Epidemiology: is the study of epidemics focusing on human populations, usually starting with an outbreak of disease within the community, epidemiologists look for exposures or other shared characteristics in the people who are sick and seeking the causative factor, helps with understanding new diseases, preventing spread new/old/ and well understood diseases Epidemiologists are people from health departments that track down the source of the disease to the very beginning which is also known as shoe leather epidemiology

Influenza— the "flu"— may seem like an old familiar infectious disease.

Even in the average year, influenza kills 250,000 to 500,000 people worldwide. Like HIV, influenza is an RNA virus, constantly changing its appearance and adept at eluding recognition by the human immune system. Each winter, viral samples are collected from around the world and sent to WHO, where biomedical scientists conduct experiments designed to predict how the virus will mutate into next year's strain. At unpredictable intervals, however, a lethal new strain of the flu virus can come along, as it did in 1918. A strain that caused the Asian flu emerged in 1957, and a third, called Hong Kong flu, arrived in 1968. Neither of the latter outbreaks was as deadly as the 1918 epidemic, although a not insignificant 70,000 Americans died from the Asian flu. In 1976, CDC scientists thought they had evidence that another deadly strain— swine flu— was emerging, and the country mobilized for a massive immunization campaign. That time, the scientists had made a mistake; the anticipated epidemic never occurred.

Public health measures to control the spread of infectious disease include both routine prevention measures and emergency measures to control an outbreak once it has begun - Many of the measures referred to above— especially those concerning links 2 and 3— come under the category of "environmental health." - Immunization— link 4— is a major weapon that has had great success against the dread diseases that created the epidemics of the past.

Even when vaccines do exist, some diseases are too rare to justify the trouble and expense of vaccinating everyone. This is where surveillance is especially important - Epidemiologic surveillance is the system by which public health practitioners watch for disease threats so that they may step in and break the chain of infection, halting the spread of disease - In the early history of public health, the solution was often quarantine— isolation of the patient to prevent him or her from infecting others. Quarantine is still used occasionally, when the disease is serious and there is no effective vaccine. For example, a patient diagnosed with tuberculosis— which is slow to respond to medication— might be ordered to stay home for 2 to 4 weeks after treatment is started until the disease is no longer infectious.

False Positives and False Negatives

False Positives & False Negatives When screening tests are highly sensitive they yield more false positives When they are highly specific they yield less false positives PH programs requires highly sensitive test to avoid missing individuals with symptoms Once you find a positive test result, they are confirmed using a more specific test Eg: mammograms followed by biopsy These two are used during screenings, for example mammograms Example of mammogram: A mammogram test is highly sensitive , any change in a woman's breast will be detected by a mammogram (could be a false positive because it is not necessary that everything picked up in a mammogram is cancer) Want to have a highly sensitive test so we do not miss people who are at high risk for developing symptoms Once an abnormality is detected, the next step is a biopsy which will make us reach a final diagnosis to see whether the abnormality seen was cancerous or not Public health programs: requires highly sensitive tests to avoid missing individuals with symptoms

Specificity

False positive: subject without the disease is misclassified as having the disease on the basis of the screening test Found something wrong with screening test and she has abnormality and then she goes to get a biopsy and then they realize she has nothing wrong So subject is getting a misleading impression that he or she has the disease and therefore undergoes psychological and economic consequences Consequences of both false positive and false negative need to be carefully utilized in a screening test When you alter decision criteria of a decision making test is when you alter the spasticity or sensitivity of the test and therefore able to make trade off The specificity of a test is its ability to designate an individual who does not have a disease as negative. A highly specific test means that there are few false positive results. It may not be feasible to use a test with low specificity for screening, since many people without the disease will screen positive, and potentially receive unnecessary diagnostic procedures.

Example of incidence and prevalence with a beaker

Flask is the community and beads represent the disease within the community As more and more beads are added, the prevalence increases Picture second on right showed the baseline prevalence and when more beads were added the prevalence rate increased Bottom picture on left: where prevalence is being studied and new incidences are being added while some cases are being removed in the deaths/ cures part of the flask Increasing prevalence is paradox of public health program When we find cure for disease or maintaining it like providing insulin for diabetes, the number of people living with diabetes increased which means the prevalence increased Prevalence can also be increased when we create new effective measures to diagnosis or detect disease A lot of time it is difficult for public health or policy people to tell people a specific treatment is effective because the prevalence has remained the same so it makes it hard to win an argument in a social political arena Increase in prevalence happens when you have early treatment and maintaining which prevents death Sometimes there are equal people being added with disease and equal people get cured or die of the disease which keeps the prevalence steady Decreased prevalence in the last picture is when prevalence lowers either through death or cure

Kinds of Epidemic studies

Goal is to determine an association between an Goal is to determine an association between an exposure and a disease or other health outcome • May be prospective or retrospective May be prospective or retrospective • Intervention study • Cohort study • Case-control study

Why do we conduct experimental studies?

Goal of public health and medicine is to modify natural history of disease to improve morbidity and mortality • We strive to provide the best preventive and medical treatment • We carry out experiments to determine the best measures of treatment based on evidence

Advantages of Case Control

Good for rare outcomes (may be only option) • Good when time between exposure and outcome is long • Can assess the relationship between multiple exposures and the outcome of interest • Typically less time consuming and less expensive than cohort and experimental studies

Governments ultimately have the responsibility of making the organized community efforts necessary to protect the health of the population, although many other organizations and community groups are also important participants.

Government's role is determined by law; that is, government's public health activities must be authorized by legislation at the federal, state, or local levels. The broad decisions of the legislative and judicial branches of government are worked out in detail by the executive branch, usually the agencies which issue regulations and carry out public health programs The ultimate authority that allows the laws to be written is the constitution or charter, whether federal, state, or local. Many nongovernmental organizations (NGO) play an important role in public health, especially through educational programs and lobbying. In recent years, stimulated in part by the Institute of Medicine's The Future of Public Health, 1 there has been increasing emphasis on community involvement in public health planning and in generating support for and participation in public health activities. This process expands the concept of the public health system to include, for example, hospitals, businesses, and charitable and religious organizations.

Case Series

Group of individuals with the same or similar illness and with the same or similar factors that may be related to the disease or injury • Descriptive design, not analytic

Virus emerging threats

HIV Influenza Ebola and Hemorrhagic fevers Hantavirus West Nile Virus SARS Dengue Virus HIV: whipped out large populations and endemic because it continues to be present Influenza: virus Ebola: once people get it, can spread rapidly and tends to kill more people, kills so many people that it limits ability to spread Hemorrhagic fevers: things that cause bleeding and difficult to treat Hantavirus: last summer in 2012, outbreak in one of national parks and caused some pneumonia (associated with mice and camping) West Nile Break: largest outbreak in 2012 in Dallas, Texas (mosquito is the vector)- spraying chemicals to kill mosquitos, usually cant see the symptoms, 1 out of 10 causes headache and 1 or 2 out 100 cause severe neurological conditions and kill people SARS: respiratory virus, spreading in ASIA, caused pneumonia Dengue Virus: emerging as global warming, cases in south Florida and keys, mosquito born virus and responsible for lots of illness and deaths especially in the tropical Virus has broad range of pathogens that do not have a good cure and some have vaccinations to prevent them

Hepatitis A

Hepatitis A is a notifiable disease in all 50 states. Because it is caused by a virus that contaminates food or water, it is important to identify the source of any outbreak so that wider exposure to the virus can be prevented. Because hepatitis is a notifiable disease, the local public health department is able to recognize when an outbreak occurs. A county may normally record only a few cases of hepatitis each year. This is the endemic level, the background level in a population. A sudden increase in the number of cases signifies an epidemic and calls for an epidemiologic investigation to determine why it is occurring. Knowing that hepatitis has an incubation period of about 30 days, it is possible to work back to an estimated date of exposure. The where question is the hardest: Where did the victims obtain their food and water during the period of likely exposure and what sources did they have in common? A large number of these investigations deal with food poisoning outbreaks caused by contamination with Salmonella or Shigella, bacteria that commonly infect carelessly prepared or preserved food, both of which cause notifiable diseases. The Milwaukee cryptosporidiosis outbreak was solved by such an epidemiologic investigation. Although cryptosporidiosis was not a notifiable disease, the epidemic was recognized because it was so severe and widespread. With some diseases, even a single case amounts to an epidemic. Measles, which is highly contagious, is preventable by vaccination. Although measles immunization for children was required by all states beginning in the 1970s, a number of measles epidemics occurred between 1989 and 1991 on college campuses. A reported case triggered a need for mass immunizations on campus. When epidemiologists found that many of the affected students had been immunized as infants, they concluded that a second vaccination was necessary for older children.

More terms

Herd Immunity: is the resistance of a group to an attack of a disease to which a large proportion of the members of the group are immune. If a large percentage of population is immune then the entire population is likely to be protected Presence of a large proportion of immune persons in the community prevents the chance of an infected person coming into contact with an unprotected person Conditions: disease agents restricted to a single host Transmission direct from one member to another Population constantly mixing together Incubation Period: interval from receipt of a infection to the time of onset of clinical illness

Herd Immunity

Herd immunity: another reason why governmental and health agencies campaign for maximum vaccination breed so many people can be perfected even if some are not vaccinated Can only work if an optimum amount of people in community is immunized or vaccinated and EDM use this certain number with a formula to see whether the particular population has achieved herd immunity For herd immunity to work, certain conditions have to be set Person can only get disease from one host, if you use multiple hosts then herd immunity might not work Transmission has to be from person to person (if you get infected from multiple agents then herd immunity will not work) Want to be in contact with people who are already vaccinated within your population

STEPS PROGRAM

Here you could see that from 2003-06 the focus was on awareness creation and later 2007-10 it was more of providing facilities where people could actually put those behaviors into practice. Similarly in schools too initially it was awareness creation and later providing actual facilities for use. All of these have in common: First there was an awareness creation and provided provisions to practice the behaviors

While the availability of statins appears to be good news for secondary prevention in people who already have atherosclerosis or who have risk factors that put them at high risk, the preferable public health approach to preventing heart disease is primary prevention such as exercise, not smoking, and eating a healthy diet. Eating a healthy diet is not easy in American society.

High blood pressure— hypertension— is a major risk factor for cardiovascular disease, especially stroke, contributing to the injury in the artery walls that is part of atherosclerosis. It also increases the risk of kidney disease. While some medical conditions are known to cause high blood pressure, most cases occur without known cause, and these people are said to have "essential hypertension." - Factors that have been linked with essential hypertension are obesity, smoking, lack of exercise, and stress. In the United States, 140/ 90 is generally considered the borderline above which blood pressure is considered too high. In this reading, 140 is the systolic pressure, that pressure exerted by the blood on the artery walls during the heart's contraction when the pressure is greatest. The diastolic pressure— 90 in this case— occurs between contractions, when the heart is relaxed. - In the United States, 140/ 90 is generally considered the borderline above which blood pressure is considered too high. In this reading, 140 is the systolic pressure, that pressure exerted by the blood on the artery walls during the heart's contraction when the pressure is greatest. The diastolic pressure— 90 in this case— occurs between contractions, when the heart is relaxed. New evidence prompted the NHLBI to issue guidelines in 2003 that classified blood pressure as "normal" only if it is below 120/ 80. Pressures between this level and 140/ 90 are classified as "prehypertension," meaning that individuals with these readings are at risk of developing hypertension.

The New York State Health Department reported in 1997 that the death rate for AIDS in the state had fallen over the past year due to the efficacy of the new drugs. The incidence of HIV remained constant. What happened to the prevalence of HIV infections?

INCREASED

Screening

Identify chronic disease early is by screening So mammograms for above women 40 yearly is being done for early diagnosis of breast cancer Screening - application of a medical procedure or test to people who as yet have no symptoms of a particular disease, for the purpose of determining their likelihood of having the disease. Have not shown, but looking to screen to see if they have early symptoms The screening procedure itself does not diagnose the illness. Those test positive in screening test will need further evaluation with subsequent diagnostic tests or procedures. All women undergo mammogram and if positive, will undergo another test which is biopsy Biopsy is a stronger diagnostic test

Objectives of Epidemiology

Identify the etiology or cause of a disease and the risk factors To determine the extent of disease found in the community To study the natural history and prognosis of disease To evaluate both existing and new preventive and therapeutic measures and modes of health care delivery To provide the foundation for developing public policy and making regulatory decisions relating to environmental problems Etiology or cause of disease: Risk factors: associated with the happening of the disease Extent of disease: how many people got the disease, who all got the disease, people in which geographic area got the disease Natural history and prognosis: what happens during the course of infection, how fatal it is, how many days does it take for people to develop symptoms , what is an incubation period, what happens if left untreated or delay the treatment, Evaluate: what are the current treatments available and are they very effective, what are the preventable measures that are currently available and how can they be changed according to the new data, are they tested, are they found effective, is there a better way of delivering it Provide the foundation: decisions for disease occurrence, signs of a host, ways of transmission

H5N1 Avian Flu

In 1997, an avian subtype of of influenza A H5N1 was described in Hong Kong Infections confirmed in 18 individuals and 6 died At the fall of 2008, more than 390 human cases had been accounted and more than 246 persons had died following H5N1 outbreaks among poultry and resulting bird-to human transmission

Legionnaires' disease

In July 1976, the American Legion held a 4-day convention in Philadelphia. Before the event was over, conventioneers began falling ill with symptoms of fever, muscle aches, and pneumonia. By early August, 150 cases of the disease and 20 deaths had been reported to the Pennsylvania Department of Health, and the CDC was called in to help determine what was causing the epidemic. The investigation determined that the site of exposure was most likely the Hotel Bellevue-Stratford, one of four Philadelphia hotels where convention activities were held. 6,7 Delegates who stayed at the Bellevue-Stratford had a higher rate of illness than those who stayed at other hotels, and many of those who fell ill had attended receptions in the hotel's hospitality suites. However, cases also occurred in people who had only been near, not in, the hotel, suggesting that exposure could have occurred on the streets or sidewalks nearby. The evidence suggested that the causative agent was airborne, but it did not appear to spread person-to-person to the patients' families. The hotel was searched for the source of the bacteria. It was eventually found in the water of a cooling tower used for air conditioning. Legionella bacteria had been pumped into the cooled air and inhaled by the victims. The bacteria were also identified in preserved blood and tissue samples collected in 1965 from victims of a previously unsolved outbreak of pneumonia which affected some 80 patients at St. Elizabeth's psychiatric hospital in Washington, DC, killing 14 of them.

Odds Ratio

In a case control study we still use a 2x2 table to determine whether there is an association between exposure and outcome, but we cannot use RR • No incidence - the investigator determines the number of cases • In case In case-control studies we calculate an odds ratio control studies, we calculate an odds ratio (OR) • OR (a/b)/(c/d) =ad/bc Case control: Investigate the wide exposures to lifestyle, genes, diet, education Controls are a sample of the population that produced the cases however in most instances the sampling fraction is not known (investigator cannot fill the whole population in the margin of 2 by 2 table or determine the rates of disease) So instead the researcher obtains odds as a rate or risk Odds is the probability that an event will occur divided by the probability that it will not occur Calculation shown at bottom: calculate the odds being the case among the exposed compared to being the case of the non exposed Example 2 times 4/ 2 times 3 In this case we would say the odds of developing In this case, we would say the odds of developing diabetes for someone who had high sugar intake were 1.33 times the odds of diabetes for someone with low sugar intake (or 33% higher). • If the disease outcome is rare, the OR is approximately equal to the RR • It is possible for an exposure to be protective (RR<1) • Diabetes (outcome) and exercise (exposure) might Diabetes (outcome) and exercise (exposure) might have an OR of 0.29 • The odds of diabetes are 71% lower in the exercise group compared to no exercise, or 0.29 times the odds • RRs and ORs can be inverted if the 2x2 table is set up differently

Cross- Sectional Study Example 2

In a survey of high school teens we ask students about symptoms of depression and also if they currently smoke • Our research question: Is smoking cigarettes associated with depression in teenagers? • The cross-sectional results would make us pause on which direction the causal effects work • Depressive symptoms could cause an increase in tobacco intake ◊ Example 2: in a survey of high school teens, we ask students about symptoms of depression and also if they currently smoke - Research question: is smoking cigarettes associated with depression in teens? - The cross selection results would make us pause on which direction the causal effects work Depressive symptoms could increase intake in tobacco consumption

Cross-Sectional Example

In a survey of older adults we ask people if they In a survey of older adults, we ask people if they have fallen in the last week and if they are taking medications for pain (opiates) • Our research question: Do opiates cause people to fall?

First, the epidemiologist must define the disease in a clear way so that there is no doubt about whether an individual case should or should not be counted. Some diseases are easier to identify than others. In a hepatitis outbreak, the symptoms are fairly nonspecific, and not every patient who comes to an emergency room with vomiting and diarrhea has hepatitis. Therefore, the epidemiologist must include the results of blood tests for liver function in his/ her case definition.

In defining a disease to be studied, epidemiologists use the term "disease" broadly: "Health outcome" is a more accurate but cumbersome description of what is to be studied. For example, epidemiologists might study the frequency and distribution of high blood cholesterol, which is not a disease but is related to the risk of heart attack, or they might study injuries due to traffic accidents, which are not diseases but are certainly significant to health. In measuring disease frequency, it is necessary not only to count the number of cases but to relate that number to the size of the population being studied, yielding a rate. Six cases of Legionnaires' disease among 1000 vacationers on a cruise ship, as happened in June 1994, is of much greater concern than if the same number of cases were diagnosed in the whole country. In calculating a rate, the denominator is generally the population at risk. The rate of ovarian cancer in a city of one million, for example, would be calculated by dividing the number of cases by the female population, not the total population of the city. Two kinds of frequency measures are commonly used in epidemiology: incidence rates and prevalence rates. Incidence is the rate of new cases of a disease in a defined population over a defined period of time. For notifiable diseases, it is ascertained by counting cases reported to the local or state health departments and dividing by the population at risk. Incidence measures the probability that a healthy person in that population will develop the disease during that time. Incidence rates are useful in identifying causes of a disease. For example, the incidence of birth defects in Europe rose dramatically in 1960 after the introduction of thalidomide, a drug used in sleeping pills. This sudden increase and its timing aroused suspicions that thalidomide use by pregnant women was the cause of limb deformities in their infants, a suspicion that was soon confirmed by epidemiologic studies. Prevalence is the total number of cases existing in a defined population at a specific time. It would generally be measured by doing a survey. Incidence and prevalence are related to each other, but the relationship depends on how long people live with the disease. A disease with high incidence could have a low prevalence if people recover from it rapidly, or if they die from it in a short period of time. However, for chronic diseases that are not lethal— arthritis, for example— the prevalence will be much higher than the incidence. Death rates, or mortality rates (the incidence of death), are often used as a measure of frequency for diseases that are usually fatal. Death rates are close to incidence rates for the most lethal diseases, such as pancreatic cancer. For diseases such as breast cancer, which many women survive, the mortality rate will be much smaller than the incidence rate.

Helminths

In soils Causing helminths that get into the body into different organs and less likely to cause death and more likely to cause chronic malnutrition or chronic anemia (chronic anemia or chronic weakness) Schistosomiasis: gets into kidneys, spread through water and gets in between toes and causes problems that back up organs and systems Liver flukes: type of helminths seen that infects that the liver, cause things to back up in terms of blood flow Roundworms, hookworm, etc.

Temporal Sequence

In some cases the outcome cannot possibly cause the exposure, so temporal sequence is not a problem • Age, gender, other innate personal attributes • Some social variables like education, income • Mortality

Public health achievements

In spite of protests from tobacco industry, we all recognize the health hazards due to smoking and hence banning smoking in some public areas has provided some other public health educational messages and measures have prevented smoking deaths Several maternal and childhood policies and interventions have resulted in reduction of infant mortality Fluoridation of drinking water Reduces tooth decay (40-70% in children) and tooth loss (40-60%) • Recognition of tobacco use as a health hazard Millions of smoking related death prevented • Healthier mothers and babies infant mortality has decreased 90% and maternal mortality decreased 99% since 1990 • Family Planning Smaller family size, fewer children and maternal deaths, fewer STDs

The major epidemic diseases are caused by parasites, viruses, or bacteria

In the 1880s and 1890s, every year marked a discovery of a new disease causing bacterium Robert Koch: developed techniques to classify bacteria by their shape and propensity to be stained by dyes Koch said billions of bacteria are harmless to humans because it inhabits the skin, throat, mouth, nose, large intestine, and vagina (so by doing so we could conclude that a specific organism caused a disease) The rules were called Koch postulates which stated that 1. the organism must be present in every case of the disease 2. Organism must be isolated and grown in laboratory 3. When injected with a lab grown culture susceptible test animals must develop the disease 4. The organism must be isolated from the newly infected animals and the process repeated Koch applied these rules in his proof that tubercle bacilli was the leading cause of TB, which was the leading cause of death in Europe at the time

Public Health and the Threat of Bioterrorism:

In the late 1990s, concern increased in the United States about the possibility that biological organisms could be used as agents of warfare and terrorism. The anthrax attacks of 2001 demonstrated that the concern was well founded. - Earlier incidents had raised awareness of the possible threat, including revelations by a Russian defector that the Soviets had developed systems for loading smallpox virus on ballistic missiles. - Concern was heightened by evidence that Iraq had produced missile warheads and bombs containing anthrax spores and botulinum toxin. The Aum Shinrikyo cult that released sarin gas in a Tokyo subway was found later to have experimented with releases of aerosolized anthrax and botulinum toxin throughout the city. Closer to home, a 1984 outbreak of salmonellosis that sickened 751 people in The Dalles, Oregon was eventually traced to intentional contamination of salad bars in several restaurants, details of which were revealed much later in a criminal prosecution of the Baghwan religious cult - Thus, the first signs of an attack are likely to be seen by physicians and hospital emergency rooms.

Case Report

In-depth descriptions of the factors related to an depth descriptions of the factors related to an illness or injury of an individual in which new possible relationships or causes are found by history, examination or testing • Descriptive design, not analytic

Relative Risk

Incidence rate among exposed (numerator) Incidence rate among unexposed (denominator) • A relative risk (RR) of 1.0 means "equal risk" across the two groups • RR > 1.0 means excess relative risk (exposed are more likely to have disease than unexposed) • RR<1.0 means exposed are less likely to have disease than unexposed

Individual vs. Community-Based Experiments

Individual • Do overweight/obese women enrolled in an exercise and healthy eating intervention reduce weight and maintain weight lose over time? Females who are overweight- individuals Community • Does reducing the cup size of soft drinks sold at fast-food restaurants reduce consumption of soft drinks in a community? Does a policy reducing the cup size of soft drinks sold at a place to eat reduce the rate of obesity or overweight in a community compared to the rate of obesity in a similar community without a policy? Community: rates of obesity within a community

Ecological studies advantages

Inexpensive • Good for hypothesis generating • Can serve as an alert system when new exposures are introduced • Researchers monitoring a birth defects registry notice a dramatic increase in a specific type of condition and could compare the trend to the introduction of new drugs Possibly occurred with Thalidomide in 1960s trends were noticed, graph shows malformations of thalidomide Increase in specific conditions to this therapeutic agent Develop a policy to decrease morbidity

Why is public health concerned with infectious diseases?

Infections tend to kill people who are younger and who are vulnerable (even with antibiotics, continues to be substantial killers and make people sick worldwide) Infections tend to be number one killer Poor people seem to be more vulnerable to infectious diseases, such as those that might be spread through water or food, associated with crowded conditions, poor nutritional status Transmission from person to person: chronic diseases we don't think of heart diseases or cancer being contagious, infectious diseases can be contagious so we need to prevent spread to overcome individual rights Takes public health to deliver treatment Antibiotic resistance: worldwide is creating emerging pathogens and we do not have good treatments for them Bioterrorism: most major threats to our future and survival 1. huge impact on worldwide mortality and morbidity 2. greater effect on low income populations 3. transmission from person-person 4. treatable and preventable 5. emerging antibiotic resistance 6. bioterroism

External validity example: How representative is our study population to general population of people living in HIV who are depressed?

Internal Validity: how comparable were participants in experimental and controlled groups More internal validity the results are, the less external they are Experimental have good internal validity and less external validity

Purpose of Randomization

Investigator: choses who receives treatment and this can be bad because they give intervention to those who actually are need it and are sick Main Purpose • Reduces selection bias (self-selection or investigator selection) in the allocation of treatment - Self-selection Eligible chose which experimental group there are in • Each participant has the same likelihood of being assigned treatment or control -Takes out subjectivity to allow people to choose • Secondary Purpose • Increases the likelihood that groups will be comparable regarding demographic characteristics that may affect study results • If there are differences, we can control for them Difference that one is receiving intervention and one is not Even If we use randomization: we cannot say they will be comparable, could be significant differences, since we have measured factors and compared differences, identify differences say on income status and control for these on analysis of study Rule of large numbers: high sample size, more likely randomization will create equal groups regarding demographic variables and any unknown variables that may impact results

One problem was that outbreaks of measles began to occur among high school and college students who had been vaccinated as babies

It became clear that the immunity conferred by vaccination in infancy wears off and that a booster vaccination is necessary in older children, a practice that is now recommended at the age of 4 to 6. - In fact, measles was declared eliminated from the United States in 2000, meaning that all cases could be traced to individuals who contracted the disease outside the country and brought it here. - The year 2014 proved to be a bad year for measles. Six hundred forty-four cases were reported from 27 states, more than half of them among unvaccinated Amish children in Ohio. 22 Then in December, a large outbreak began in California that spread across the country. - The first reported case was an 11-year-old girl who had visited a Disney theme park in southern California during the exposure period and was hospitalized. She had not been vaccinated. The source of the exposure has not been identified, but the strain of the virus was the same as one that had recently caused a large outbreak in the Philippines and has also been detected in other countries. Disney theme parks attract many international visitors, one of which presumably carried the virus to California in 2014. - Given the uncertainties with polio eradication and the difficulties with achieving universal immunization in the United States, the prospect for measles eradication worldwide is doubtful.

Bacteria Emerging Threats

Legionnaire's: cases of people staying in hotel, found something in water supply that address air conditioning vents, known to be caused by bacteria and caused pneumonia Lyme disease: spread by bacteria that is carried by ticks (ticks associated with Lyme disease but not the cause of disease, the bacteria that is carried is the cause of disease) E. Coli: food borne and see outbreaks in hamburger meat, normal bacteria seen in our body in mouth, skin, and vaginal areas (pathogens that are harmless and living with us, this E. Coli produced a toxin and this caused kidney disease and death) MRSA: skin infection that can be transmitted by athletes, can cause a rash, gets in blood can be serious infection (antibiotic resistance)- we can see it is an emerging infectious disease TB: 1/3 of population is infected and most is latent and laying low with no infections, if people become weak- TB can reoccur and people can have symptoms (AFRICA, India, and tropics), takes 6-9 months of medication to cure it and incredibly contagious)

Risk Assessment

Life expectancy in US= 75 years YPLL for a person died between 15-24 years of age is 55.5 YPLL Step 1: 15+24/2=19.5 Step 2: 75-19.5=55.5 Risk Assessment: Identifies events and exposures that maybe harmful to humans and estimates the probabilities of occurrence as well as the extent of harm they may cause Risk Perception: People's perceptions regarding risk of an incident/ disease. Depends on dread and knowability More dreaded the risk: less acceptable it is More unknown the risk is: less acceptable it is Risk assessment example: before the seatbelt law there was a risk assessment, before the loss to protect occupational hazards, which occupational is a higher risk in compared to another occupation Depending on risk assessment, the rules and regulations are different, for disease causation we have a risk assessment so most of the prevention/rules are based on this concept Motivation to adopt preventable behaviors are higher with risk perception based on this concept For example, we all know that not following a healthy lifestyle could cause chronic diseases, but is the risk perception high enough that everyone exercises and takes prevention measures Ebola: anybody cares about it will take measures- more unknown and dread the risk- turn adoption of prevented behaviors

Loss to Follow-Up

Loss to follow-up is expected • Side effects of treatment Don't feel they need to be in study because they are better or either to stop participation • Knowledge/feeling that they are receiving placebo They know what group they are in and don't like they are in treatment group versus controlled Stringent: too hard or too time consuming • Stringent study requirements • Changes in life situation • May move away • Became pregnant Prospective data collection over time: when we say loss to follow up, cant get in touch with participants that were enrolled in the study

Challenges of Case Control

May be difficult to find appropriate controls • Need a sound method for assessing past exposure • Cases may remember exposures better or have thought more about what may have caused their disease (recall bias) • Provide indirect estimate of risk • Temporal relationship difficult to determine • High potential for bias (recall, selection, etc.)

Selection of cases

Need to define a case conceptually • Standard diagnostic criteria • Severity of the disease • Subjective or objective criteria • Ideally, identify and enroll all incident cases in a defined population in a specified time period want to avoid a case status

Measles

Measles, another viral disease that could in theory be eradicated, offers an example of what happens when public health relaxes its vigilance. Before a vaccine was available, almost all children contracted measles, causing 400 to 500 deaths a year in the United States and 4000 cases of chronic disability from measles encephalitis. - Given the uncertainties with polio eradication and the difficulties with achieving universal immunization in the United States, the prospect for measles eradication worldwide is doubtful. - Measles is still endemic in some European countries as well as at higher levels in Africa and Southeast Asia. - An attempt to eradicate an eradicable disease can backfire if it is not conducted with sufficient political will, knowledge, and resources. This was the case with malaria, which was the target of an international eradication campaign in the 1950s and 1960s. There is no nonhuman reservoir for the malaria-causing parasites, but the route of transmission is a vector, a certain species of mosquito. The primary weapon in the eradication effort was the pesticide DDT. - While the campaign produced dramatic results, funding ran out before the objective was achieved, and there was a resurgence of the disease with greater impact than ever. A combination of factors contributed to the calamity: DDT-resistant mosquitoes emerged; the pathogen developed resistance to the main antimalarial drug, chloroquine; and populations in former malarial areas lost their immunity to the disease because of lack of exposure. - Now, malaria is one of the most widespread potentially fatal infectious diseases in the world, killing an estimated one million people annually, mainly children. - The disease occurs mainly in tropical and subtropical areas and has been largely eliminated in the United States, but global climate change and international travel could contribute to the re-emergence of malaria as a public health problem in the South.

Many industries are opposed to public health measures for economic reasons. Which of the following industries is least likely to do so?

Medical supply industry

Public health vs medical health

Medicine is concerned with individual patients while public health caters to the community as a whole First bullet: As in medicine, public health also carries out the functions of assessment which is similar to the diagnostic function of medicine, policy development is similar to the doctors development of a treatment plan for sick patient and assurance that has been compared to actual treatment of a doctor that is making sure the services needed for the protection of public health in the community available and accessible to everyone Medicine focusses on healing those who are ill while public health focusses on preventing illness Second bullet: Focus on prevention on public health makes it more abstract since the benefits of prevention programs are not seen immediately as you see the benefit of the doctor treating sick patients The result of a medical treatment of a sick patient is very recognizable and visible, this lack of immediate benefits have results in controversies of public on huge spending of huge tax spending on money on public health programs Public health contributes more to the health of the population as a whole than medicine does Several of the public health achievements that have resulted from various health programs in our country provide enough evidence to prove this. For example: Life expectancy of Americans has increased significantly from 45-75 years over the course of 21st century due to various huge public health policies and programs spanning from nutrition, housing, sanitation, and occupational safety Public health is more abstract than medicine and achievements are long term. Effective public health programs saves a lot of money as well as lives

Tobacco usage

More than 42 million adults- 1 of every 5-said they currently smoked 30 percent of all cancer deaths 21 percent of cardiovascular disease 435,000 deaths each year and 35,000 by second hand smoke Each day 3,200 youth ages 18 years or younger smoke their first cigarette E cigarettes (Electronic nicotine delivery systems)- long term effects not yet known We took a long time to make people stop or reduce smoking and bring laws to restrict smoking Sudden boom of e cigarettes followed by fancy ads with very young group of people glamourizing it.....and Tobacco giants enter into the e cig market has created a new fear of renormalization of smoking which could lead to resurgence of smokers.

Considerations for cohort

Occupational Studies • "Healthy worker" effect • Small population of interest • May be challenging to separate exposed and unexposed in a small geographic area especially if unexposed in a small geographic area, especially if the exposure is an environmental contamination • Misclassification influences results

Diabetes

Officially, diabetes ranks seventh overall as a cause of death in the United States; it is fourth among American Indians and fifth among blacks, Hispanics, and Asians. Many death rates due to diabetes are associated with heart disease - Heart disease death rates are two to four times higher for people for people with diabetes than those without it Diabetes is a major cause of disability. Although it is usually treatable and can be controlled over long periods of time, there has been little that public health could do to prevent the disease except to make unpopular recommendations for changes in lifestyle. The Centers for Disease Control and Prevention (CDC) has referred to twin epidemics of diabetes and obesity, because obesity greatly increases the risk of diabetes, and the number of Americans who are obese has been increasing rapidly.

Public health measures to protect airline passengers and American residents from exposure are far from perfect. The CDC reports that despite the State Department's requirement that immigrants and refugees undergo screening overseas, approximately 125 individuals with active TB arrive in the United States each year, mainly foreign visitors, foreign students, and temporary workers.

One example cited by the CDC occurred in 2011, when the Ohio Department of Health reported to the CDC that a college student from China had arrived with active TB. She had travelled from Japan on a flight to California that lasted more than eight hours, and then taken two connecting flights to reach Ohio. As required in such a situation, the airlines were asked to identify passengers who were potentially exposed by sitting in the same row or two rows in front of or in back of the infected person.

Koch also identified Vibrio Cholera as the cause of cholera

Other disease-causing bacilli identified during that period were those that cause plague, typhoid, tetanus, diphtheria, and dysentery. Cocci: round shaped bacteria and includes the following - streptococci, which cause strep throat and scarlet fever - staphylococci, which cause wound infections - pneumococci, which cause pneumonia. Syphilis which is caused by a cork screw bacterium called a spirochete

Parasites Emerging Threats

Parasites: get in red blood cells, multiply and explode, fever in response, anemia in response to damage of blood cells Malaria harmful for younger people and pregnant Endemic, mosquito born virus, a lot of control deals with mosquitos or human contact with mosquitos 4 different type of parasites that cause malaria Pneumocystis: people with HIV or immune deficient because they got an organ transplant, these type of people are susceptible to infectious agents and now seeing emergence of opportunistic infections when immune systems are compromised and as people get old immune systems get compromised

Which of the following is true of politics and public health?

Politics is an essential element of democratic governance

Ecological Studies

Population are the unit of are the unit of study • Countries communities schools families • Compare exposure and disease rates between groups • Ecological studies can provide an idea of trends and associations, but it is difficult to link cause and effect

Other health concerns and behaviors

Prescription Drug Abuse Obesity Concussions and other sports injuries E Cigarettes Firearm Injuries Mental Health Huge increase in opioid usage with prescription drug abuse and epidemic of drug over dose - Increased public awareness - Practice guidelines - Lots of research - New laws required now to immediately cup someone who has an illegal prescription at hand Obesity: children and adults that contribute to chronic emissions and current and future health care costs Concussions: - short term and long term research on sports injuries - Prevention on sports needed with large amounts of injuries and sports with higher rates of concussion among children, adolescents, and youth - Good training, proper techniques of training, rules enforcement, and developing education E Cigarettes - Quality control and potential impurities, smoking perceptions, and lack of research - Creates a path to tobacco use among those who do not currently smoke cigarettes- people who are against it - Nicotine exposure to young children due to the liquid nicotine use to refill cigarettes Firearm injuries - Less research and protective factors for firearm injuries - Need to target firearms to prevent injuries and lots of deaths Mental health: - In 2009, US had 60 percent of people with mental illness and did not receive any treatment and 40 percent patients with serious mental health also did not receive any treatment Main barriers to access mental health: 1. Do not have access to healthcare 2. Financial issues so lack of insurance Stigma

Incidence and Prevalence

Prevalence: Defined as the number of affected persons present in the population at a specific time divided by the number of persons in the population at that time. Incidence: Rates of new cases in a defined population over a defined period of time. Counting the cases reported to a local or state health departments and dividing by the population at risk. It also gives us the probability that a healthy person in that population will develop the disease during that time. For incidence to be meaningful, the denominator must have the potential to become part of the group that is counted as the numerator.

Prions Emerging Threats

Prions: emerging threat, smaller than viruses, pieces of DNA CJD: occur in older people, strange neurological condition Mad cow disease: prion agent acquired may years before symptoms develop and associated with meats or brains of animals combined into meats (disease is not able to be cured and neurological damage) Banning imports of meats from certain countries or eliminating large herds of livestock if they think they could be infected

Probability

Probability: Uncertainties are quantified using probabilities P value: expresses the probability that the observed result could have occurred by chance alone. Expressed as p<0.05 (finding is statistically significant) If the same test is repeated 100 times, you will get the same test result 95 times. The chance of you getting a different result is only 5 times or less that 5times. Therefore the test result is significant. Confidence Interval: gives a range (+/_ percent) Confounding variables could play spoiler! (eg: coffee drinking and pancreatic cancer)

Cohort example

Rochester Radiation Cohort • During 1940s and 50s, radiation treatments were believe to cure or prevent some infections believe • The radiologist who worked on the Manhattan project moved to Rochester and undertook a cohort project to study of children treated with x-rays for an enlarged thymus All children treated in Monroe County NY identified and located • All their siblings who were untreated were unexposed part of the cohort • Every 6-7 years participants were surveyed about about conditions developed • Results: Risk for thyroid cancer was 14.1 times higher in exposed than unexposed

Public health and politics

Public health policies and regulations have always been controversial Most public health measures have a negative economic impact on somebody or other, for example constant conflicts with the tobacco industry (even though smoking related deaths and diseases are common, it has been difficult to enforce a restriction on smoking due to strong lobbying on tobacco industry Paternalism: huge protest against requirement with seatbelts when traveling in a car and helmets when riding a motorcycle Sex education in schools and provision of contraceptives is strongly opposed by certain religious groups who believe that they promote immoral behavior Alcohol and drug policies were also strictly opposed saying that Each opposition has consequences such as funding cuts for research of many preventable diseases so regulating public health has continued to be a difficult task • Benefits of public health measures are long term and hence difficult to comprehend • Cost of public health measures are easier to calculate than the benefits • Public health measures could sometime be viewed as government's restriction on individuals freedom which are often criticized as 'paternalism' • Moral and religious oppositions especially in areas of sexual and reproductive issues such as AIDS, pregnancy, abortion, contraceptive use

Scientists at the National Institutes of Health are collaborating with the government of Thailand to test the effectiveness of a new vaccine in preventing HIV infection among sex workers. The women were randomly assigned to receive the experimental vaccine or an injection of salt water, and the women are then monitored for development of HIV infection. What kind of epidemiologic study is this?

Randomized Intervention

Influenza- diagnostic testing

Rapid PCR: advanced genetic testing, very specialized testing Antibody based test: immunofluorescence Sensitive and specifics: how accurate is test, give you a positive result when people do not have flu Rapid influenza test: used in doctors office and moderate sensitive because it can miss it if it is flu and high specifics meaning if it says you have the flu you probably do Viral culture: gold standard that we can grow the flu virus and requires special type of cells to grow on, can be insensitive sometimes meaning if it does not grow, does not mean flu Serologic: blood test and look at antibodies to see if they ever had flu, good at detecting past infections

Rates and other calculated statistics

Rates and other calculated statistics Rates put the raw numbers into perspective by relating them to the size of the population being considered. Vast quantities of health-related data are collected on the American population, data that are used to assess the people's health and to evaluate the effectiveness of public health programs. For these purposes too, the raw numbers are subjected to statistical adjustments that yield various rates useful in making comparisons and identifying trends. Rates are usually calculated using the population at risk for the denominator. Confidence interval: gives us a range in which the study is true Confounding variables: Was told that coffee causes pancreatic cancer, however they were wrong because the researchers forgot to use smoking as a studying variable so maybe it could be the smoking that caused the cancer Statistics makes possible the translation of data into information about causes and effects, health risks, and disease cures. Because health is determined by many factors— genes, behavior, exposure to infectious organisms or environmental chemicals— that interact in complex ways in each individual, it is often not obvious when or whether specific factors are causing specific health effects. Statistics indicates that an apparent health effect may be simply a random occurrence.

In a case-control study that found an association between breast cancer and air pollution, 500 women who had recently been diagnosed were asked what industries were within a mile of their home twenty years ago. The controls were 500 healthy women. What is the most likely source of error in this study?

Reporting bias

The Nurses' Health Study was a type of cohort study.

TRUE

Sensitivity

Sensitivity and specificity are measures of a test's ability to correctly classify a person as having a disease or not having a disease. Need to be benchmarked against an agreed gold standard test The gold standard test is regarded as definitive For example: in case of cancer-biopsy and in case of other diseases is autopsy which is too late Actual gold standard test can be invasive meaning unpleasant and sometimes too late Sensitivity refers to a test's ability to designate an individual with disease as positive. A highly sensitive test means that there are few false negative results, and thus fewer cases of disease are missed. Saying that the person has the disease which is positive Person does not have the disease it becomes negative Ideal would have a positive result if and only the subject has the disease and negative result if and only the subject did not have the disease High Sensitivity has few false negative results so fewer cases of the diseases have been missed Consequences of too many false negatives: False negative means subject with the disease is misclassified as not having the disease on the basis of the screening test For example: went to mammogram, women is identified as having no cist or abnormality in her breast so she is a false negative (person is mislead by the treatment so does not undergo anymore suitable diagnostic test)- she had an abnormality in her breast but the screening test did not pick it up and therefore she was classified as not having the disease and will not be referred to a biopsy

2 by 2 table

Set up a 2x2 table A: exposed, ill (whatever pathogen and risk the pathogen) B: number of well who have been exposed C: number of ill who have not been exposed D: number of well who have not been exposed RR= a/(a+b)/c/(c+d)

Randomization that did not work well

Small sample size and randomization did not completely work on all demographic variables Randomization produced two groups that were not equal in white distribution (considered statistical significant) So here control race With relatively large sample size, randomization can produce two groups that are similar in term of baseline characteristics and factors we cannot measure

The Supreme Court decision in the case of Jacobson vs. the Commonwealth of Massachusetts set a precedent allowing a state to restrict an individual's freedom for the common good. What specific issue did the case apply to?

Smallpox vaccination

Social and Behavioral Sciences

Social and Behavioral sciences: public health is now relying on this to achieve its goal of improving health of the population Over the last century we have identified several disease causing agents and there modes of transmission, we also understood that several of the diseases could be controlled by modifying ones behavior, can lead in understanding peoples behaviors and provide recommendations on how to modify their behavior patterns so that they could prevent contracting certain diseases or illness that could cause death or disability

John Snow Cholera Outbreak

Southwark & Vauxhall obtained water from the Thames river below London (polluted) • Lambeth obtained water from Thames above London (less polluted) RR=5.5 Those residences that Southwark and Vauxhall would have 5 times the risk of death due to cholera

Ecological Fallacy

Stating an association at the individual level based Stating an association at the individual level based on data at the group or population level Major concern with ecological studies • We do not know if people who are dying of heart disease are individually those who drink less - When we attribute causes of individual outcomes and they are attributed to characteristics of groups that are correlated to geographic areas So we do not know if people who are dying of heart disease are individually those who drink less (could be other factors on individual levels associated with increase in death rates) As income decreases, so does the risk of traffic injuries (example from powerpoint)

Statistics

Statistics: helps public health understand the prevalence, birth rate, death rate, and determining how sick or healthy a community is, statistical calculations also help us to understand risk from exposure disease causing agents in the environment, allows us to test the effectiveness of a drug to treat a certain disease in the community

Which of the following is a not common source of error in a small cross-sectional study:

Subjects do not adhere to the prescribed regime

United States that measles immunization causes autism. Autism often becomes apparent at about the age when the vaccine is given. Consequently, some parents refused to allow their children to be vaccinated against measles. Similarly, unfounded stories about side effects of the pertussis (whooping cough) vaccine— that it might cause sudden infant death syndrome (SIDS)— led many parents to resist that vaccine.

Suspicions about the safety of vaccines were exacerbated by the actions of British surgeon Andrew Wakefield, who in 1998 published a fraudulent paper claiming that the measles-mumps-rubella (MMR) vaccine was linked to the onset of autism. - Wakefield's paper was published in a highly regarded journal, The Lancet. Many other scientists doubted the claims, however, and a thorough investigation eventually found that Wakefield was guilty of misconduct. He had misrepresented the facts about the children he claimed to have studied and had cooked up a scheme to profit by filing lawsuits against the drug companies that manufactured the vaccine Because parental concerns became so widespread, the Institute of Medicine has conducted periodic reviews of the latest evidence on vaccine safety. - In 2003, it published a review on SIDS and concluded that "the evidence favors rejection of a relationship between some vaccines and SIDS." - In 2004, the Institute of Medicine reviewed evidence on a possible link between the vaccine and autism and again concluded that "the body of epidemiological evidence favors rejection of a causal relationship between the MMR vaccine and autism."

Ted Talk Ghost Map

Ted Talk: The Ghost Map London ◊ In 1854: important one London was the largest city on face of planet and largest city that was built Victorians were trying to build a whole scale of new living that we call metropolitan living, was a complete disaster- people had cesspools of human waste (throw down buckets there and hope it would somehow go away) ◊ All of stuff had accumulated- smelly city because lots of livestock- people had cows in attics that they would use for milk ◊ Entire public health system became convinced that it was the smell that created these diseases, now cholera was the great killer of this period ◊ Convinced that smell was a problem, Nuisances Act got everyone to empty their cesspools and pour it into the river, this ended up increasing the cholera outbreaks because cholera was in the water (waterborne disease because it is something you ingest) ◊ John Snow argued that cholera was a water borne disease, public health ignored ◊ It was a great case study in how cultural change happens because a good idea eventually comes to win out over much worse ideas ◊ A child, 5 month girl, Baby Luis contracted cholera on broad street, turns out cesspool bordered on extreme local water pump known for best water pump in SOHO, little girl contaminated the water (10 percent of the people died within 7 days) ◊ Snow believed from the water pump incidence that the real source of cholera was in the water supply (prob involve a single point source that everything was getting at) ◊ Enlisted the help Henry Whitehead a minister- knew everyone, found many people who drunk from pump and Snow made a map of outbreak (people drank from pump were getting sick) ◊ Needed some type of higher level of view- created a map which basically represented all deaths as black bars (further away from pump see less deaths) ◊ With map and whitehead, authorities started to slowly come around, by 1866- next big cholera outbreak, authorities believed in Snow and started to build the sewers (last time London has seen cholera outbreak) ◊ It is possible to solve problems if we listen to reason ◊ Because of what John Snow did, because of the map, and the whole series reforms, we can take for granted that cities that have 10 million people, cities like this in fact are sustainable

Public Health Response to Emerging Infections:

The Institute of Medicine has undertaken several studies to address the environmental, demographic, social, and other factors leading to the emergence or re-emergence of infectious diseases. - One of its conclusions is that most of the emerging infectious disease events have been caused by zoonotic disease pathogens— those infectious agents that are transmitted from animals to humans. - Factors that contribute to the risk of this animal to human transmission include human population growth, changing patterns of human- animal contact, increased demand for animal protein, increased wealth and mobility, environmental changes, and human encroachment on farmland and previously undisturbed wildlife habitat. Clearly, these diseases are an international problem, and dealing with them requires an international response. Effective control of emerging infectious diseases requires worldwide disease surveillance focusing not only on human populations, but also on domestic animals and wildlife. - CDC is collaborating with, in addition to the World Health Organization, the World Organization for Animal Health, and the Food and Agricultural Organization of the United Nations. Other priorities that the Institute of Medicine has identified for controlling emerging infections include reducing inappropriate use of antibiotics by banning their use for growth promotion in animals and by developing improved diagnostic tests for infectious diseases so that antibiotics are not used for viral diseases. The Institute of Medicine also recommends developing new vaccines, new antimicrobial drugs, and measures aimed at vector-borne diseases.

The Resurgence of Infectious Diseases Chapter 10:

The appearance of acquired immune deficiency syndrome (AIDS) in the early 1980s challenged the widely held belief that infectious diseases were under control. However, there had been intimations during the previous few decades that the microbes were not as controllable as generally believed. The Biomedical Basis of AIDS: - By the turn of the 21st century, the exotic disease that seemed to strike only gay men has turned into a world-wide scourge: The human immunodeficiency virus (HIV) now infects over 35 million individuals and kills more than 1.5 million a year. - In the United States as of 2012, some 658,500 people had died of AIDS. - HIV is a retrovirus, a virus that uses RNA as its genetic material instead of the more usual DNA. - Retroviruses have long been known to cause cancer in animals, and they were extensively studied for clues to the causes of human cancer Retroviruses infect cells by copying their RNA into the DNA of the cell, penetrating the genetic material like a "mole" in a spy agency. This DNA may sit silently in the cell, being copied normally along with the cell's genetic material for an indefinite number of generations. Or it may take over control of the cell's machinery, causing the uncontrolled reproduction typical of cancer.

During 2000

The cause of death during the time of death, the diagnosis was hard deceased But the actual cause contributed to heart disease such as tobacco, poor diet or physical inactivity, and alcohol consumption Similarly cancer, the diagnosis during time of diagnosis was cancer but there were a series of events that happened in their life prior to the death that has actually caused the development of the disease Diagnosis at the time of the death as the cause and the actual causes of death- good comparison

Why Screen?

The goal of screening is to reduce morbidity or mortality from the disease by detecting diseases in their earliest stages, when treatment is usually more successful. Examples of screening tests: Pap smear, mammogram, clinical breast exam, blood pressure determination, cholesterol level, eye examination/vision test, and urinalysis.

A variety of environmental factors are responsible for the recent emergence of so many new pathogens. Human activities that cause ecological changes, such as deforestation and dam building, bring people into closer contact with disease-carrying animals. Modern agricultural practices, such as extreme crowding of livestock, intensify the risk that previously unknown viruses will incubate in crowded herds and be widely dispersed to human consumers.

The popularity of exotic pets in the United States also can lead to the spread of pathogens, like monkeypox and perhaps West Nile virus, from animals or birds to people. The ease and speed of international travel means that a new infection first appearing anywhere in the world could traverse entire continents within days or weeks. This was dramatically illustrated by the emergence and rapid spread of SARS. The SARS virus is believed to have been transmitted to humans from an animal species used for food in China, possibly the civet cat.

Predictive Value

The probability of having the disease, given the results of a test, is called the predictive value of the test. Positive predictive value is the probability that a patient with a positive (abnormal) test result actually has the disease. Negative predictive value is the probability that a person with a negative (normal) test result is truly free of disease.

Chain of Infection

The public health approach to controlling infectious diseases is to interrupt the chain of infection 1. Pathogen: The pathogen is a virus, bacterium, or parasite that causes the disease in humans. 2. Reservoir. The reservoir is a place where the pathogen lives and multiplies. Some pathogens spread directly from one human to another and have no other reservoir. Others, however, may infect nonhuman species, spreading from them to humans only occasionally. Plague, for example, is a disease of rodents that is transmitted to humans by the bite of a flea. Rats are the reservoir of plague. Raccoons and bats are reservoirs for rabies, which spreads to humans only through the bite of a rabid animal. Contaminated water or food may also serve as reservoirs for some human diseases. 3. Method of transmission. The pathogen must have a way to travel from one host to another, or from a reservoir to a new host. - The flea is a vector for plague, transferring the plague bacillus from rat to human by sucking it up when it bites the rat and then injecting it into a human host with a second bite. Food-borne diseases are transmitted when a person eats contaminated food; water-borne diseases are transmitted when someone drinks contaminated water. Many respiratory diseases are transmitted by aerosol. AIDS, syphilis, gonorrhea, and a number of other diseases are transmitted by sexual contact. Susceptible host. Even if the pathogen gains entry, a new potential host may not be susceptible because the host has immunity to the pathogen. Immunity may develop as a result of previous exposure to the pathogen, or the host may naturally lack susceptibility for a variety of reasons. Most microorganisms are specifically adapted to infect certain species. Canine distemper virus, for example, does not infect humans. Even within species, susceptibility to specific viruses varies among individuals. Scientists have been puzzled why a very few people who have been repeatedly exposed to the human immunodeficiency virus (HIV) do not become infected; recent studies have found a genetic mutation that makes them resistant to the virus.

Characteristics of Chronic Diseases

They are not passed from person to person Multiple causes Difficult to recognize significant risk factors and establish preventive measures Disease tend to develop over long periods of time Gradual onset Hypertension is a great example of chronic disease and also has gradual onset

Which of these is NOT true about infectious diseases:

They have a greater effect in higher income populations

Data Collection

Treatment • Keep track of which treatment group the participant was assigned • If there are multiple treatment arms, keep track of which therapy each person received Baseline Data • Collect baseline characteristics and other risk factors • Compare the treatment groups for differences that need to be controlled for Secondary purpose was achieved with equal purposes of having an experimental and controlled group

Risk Factors of Cardiovascular Disease

Two of the three leading causes of death in US Risk increases with age, Higher in men than in women Higher among African Americans than in Whites Risk Factors: High blood cholesterol HDL-high density lipoprotein (good cholesterol) lowers the risk of heart disease LDL - low density lipoprotein (bad cholesterol) Atherosclerosis-hardening of arteries, recently identified certain bacteria found in plaque Diet- milk, meat & eggs in excess High BP major risk factor Injuries to artery walls Kidney diseases Normal is below 120/80 Between 120/80 and 140/90 are prehypertension Dietary salt Smoking Interaction of several risk factors

Vector:

Until the 20th century, infectious diseases were the main cause of death Bubonic plague, the "Black Death," is said to have wiped out as much as 75 percent of the population of Europe and Asia in the 14th century. TB was main cause of the death in England in mid-19th century In the 19th century, mortality rates from TB, typhoid and respiratory and gastro diseases were double what they became in 1930 Through public health measures of purification of water, disposal of sewage, pasteurization of milk, improved nutrition and personal hygiene played a role in the 1960s by reducing infectious diseases

Graphs of Vaccine Preventable diseases and Motor Vehicle Deaths

Vaccine preventable diseases: Vaccination of each birth cohort in the US prevents approximately 42,000 deaths and 20 million cases of disease The graph here shows the fall of measles prevalence from 1950-2001 as a result of the vaccination Decline of motor vehicle deaths despite the huge increase in the number of vehicles and miles traveled from 1925-1995 due to stricter enforcement of seatbelts and motorcycle helmets

Influenza

Very different strain: because it killed young people Only 24 hours after flu, secretions in throat caused people to drown in their own secretions This case was pathogenic: makes people very sick This year we have lots of old people with flu 1918-1919 H1N1 type influenza pandemic killed 20-50 million million persons with with 549,000 deaths 1918 influenza killed many aged 20-30 range within 1-2 days

Cohort Study

Were exposed: has the disease and does not have the disease were not exposed: has the disease and does not have the disease People are sampled based on exposure Cohort studies: examine multiple healthy effects of an exposure Subjects defined to exposure level and followed for disease occurrence Participants are followed over time and and rates of incident disease/outcome are compared for exposed and unexposed

Confounding

What is the limitation to 2x2 tables? • Confounding: factor(s) other than the exposure of interest are related to both exposure and outcome and confuse the the relationship we re' interested in Examples of confounding variables • Risk of death in Florida is higher than Alaska • Confounder: age structure of states • Male gender and shark attack risk • Confounder: gender • Alcohol as a risk factor for lung disease • Confounder: smoking Handling confounding variables: First we must measure confounders • In the analysis (typically regression) • Make sure the factor is associated with exposure and outcome • Add confounders into regression model • Result: adjusted model

Influenza virus of animal origin

influenza A is a zoonotic infection more than 100 types infect most species of birds, pig, humans, dogs, and seals sporadic severe and fatal human cases of infection with highly pathogenic avian influenza A virus have been identified among people who have unprotected contact with sick or dead bird (H5N1) Swine influenza A (H1N1), A (H2N2), and A (H3N2) viruses are endemic among pig populations Endemic in pigs: respiratory problems with cough and sneeze, if you are worker, you can get viruses and virus can recominate and create new viruses One health: humans and animals are connected, transmission of pathogens can involve animals getting to humans Avian influenza A: fear that if it could spread better from person to person, if people catch it they are most likely to die so it most likely is seen from animal to human

An intervention study to determine whether a vegetarian diet can help college women to lose weight, 500 residents of a women's dormitory were divided into two groups: one that ate in a vegetarian dining hall and one that ate a normal diet. Women were allowed to choose which group they wished to be for this study without the researcher assigning them to any groups. After three months, the vegetarian group had lost an average of 10 pounds while the control group had not lost weight. What is the most likely source of error in this study?

selection bias

Numbers of infections

since 1980, the estimated annual overall number of influenza associated hospital ranged 55,000 to 431,000 per annual epidemic (mean 226,000) Hospitalized: cannot breathe without oxygen or some type of support (flu is a respiratory virus) the estimated number of deaths attributed to influenza ranged from 17,000 to 51,000 per epidemic (mean 36,000) Shows that percentage of overall flu infections That typically, Feb has the most influenza case (2008-2009)

What is epidemiology?

studies the patterns of disease occurrence in human population and the factors that influence these patterns Derives from a Greek word that means upon people, so the diseases are infections that occur on people An epidemic is an increase in the frequency of the disease above the expected rate which is called the endemic rate Epidemiologic methods are used: to investigate causes of diseases, to identify trends in disease occurrence that may influence the need for medical and public health services, and to evaluate the effectiveness of medical and public health interventions Investigate causes of diseases: example of Ebola, where did this happen, from where did this start, who is the first victim, who was the host or where did this start from, how was this transferred from the agent that is the individual, the person, the animal, or whatever the disease causing agent is resting and how did this get transferred to a human being To Identify trends: who are all getting infected, what season of the year are people getting infected, people in which geographical area is getting infected, which category of people so are they only children or are only older adults, men, women (Epidemiologists identify trends to look at how the dead people got their diseases based on past trends) Evaluate the effectiveness: evaluate the existing intervention as well as the new interventions that have been discovered or in the process of being established; also what type of treatment is effective because some treatments are only effective for certain populations while others are effective on another set of populations All of these are being tested, evaluated, and found by disease specialists ULTIMATE GOAL IS TO USE THIS KNOWLEDGE TO CONTROL AND PREVENT THE SPREAD OF DISEASE

Outcome Assessment Example

• AIDS diagnosis among HIV-infected • < 200 CD4+ T cells per cubic millimeter of blood • CD4+ T cells accounting for less than 14% of all lymphocytes • One or more opportunistic illnesses, such as Kaposi's Sarcoma, Encephalopathy, Wasting Syndrome, etc. • Death from myocardial infarction • Examination of autopsy reports, death certificates, medical records, and information obtained from the next of kin or other family members

Outcome Assessment

• Clinically relevant outcomes should be clearly defined at the beginning of the study • Preventive studies: Precursors of disease or first occurrence of disease • Therapeutic studies: Symptom improvement, length of survival, or disease recurrence • All study groups must be monitored for the outcome in the same fashion • Evaluators should be trained and blinded, if possible • Minimize misclassification bias • Minimize investigator bias Define measurement or outcome of treatment Outcomes can be measured through physical exams, medical records, combination or two or more Could get a self-report and follow with the medical record to verify that it is accurate

Experimental studies are useful for evaluating:

• Drugs, other treatments for disease • Medical/health care technology • Methods of prevention • Programs for screening and diagnosis • Methods of organizing and delivering care • Health care policies • Community health programs • Behavioral intervention programs (Implemented at community level the behavioral programs)

Disadvantages of Experiments

• Expensive and time-consuming • Will want to study an outcome that happens in a short time interval • Ethical concerns When to stop study and how to gain informed consent • May require a large sample Based on sample size, need a large group of people to detect a small difference between two groups • Strict exclusion criteria and 'artificial setting' that limits generalizability Eligible participants, but might not be representative of whole population • Compliance and loss to follow-up

What is an Experimental Study?

• Gold standard of epidemiologic research • The researcher determines who is exposed (treatment typically)High status in validity allows them to pick up all and modest effects Assess the efficacy of the treatment or effect of the expose Now when humans are the subject, there is not nearly as much control you would see in animal studies • Outcomes in treated groups are compared to outcomes in an equivalent control group Represents controlled laboratory experiments: that's why experimental studies are at the top Controlled: Regulate all outcomes of experimental conditions and allow subjects to differ in terms of testing hypothesis If testing the chemical in mice, would include genetically similar or identical mice, then assign the mice to a treatment or controlled group and maintain the same environment for the mice

What is public health?

• Not easy to define or comprehend • Constant struggle to understand its mission and reach a definition Public health professionals and public health themselves struggle to find a clear census about the mission of public health

Inclusion/Exclusion Criteria

• Once research question is identified, must establish inclusion and exclusion criteria • Age, gender, and other demographic factors • Health status/health conditions • Disability, cognitive function • Participants are recruited based on specific criteria and their informed consent is sought Inclusion: characteristics that participants must have to be eligible, come up with these based on research question So behavioral treatment for depression among people living with HIV, the inclusion criteria: would be people living with HIV based on an HIV test and those with clinical depression based on a clinical question test Exclusion: set of specific that would prevent someone from study that did meet inclusion, will be based on research question, because we want to see behavioral effect, exclude those that are already receiving any treatment for depression (if we have people who are already receiving treatment and see effect of intervention that we did....cant tell the difference)

Advantages to experiments

• Provide the greatest control over: • Amount of treatment • Timing and frequency of treatment • Period of observation • Blinding of participants and researchers can reduce bias in assessment of outcomes • Provides the strongest evidence for causal inference (prospective design) Ensure that test or treatment precedes the outcome of interest, say that treatment causes the outcome then some other • Confounding can be reduced (and nearly eliminated) with randomization Be comparing similar groups- to reduce bias • Detailed information collected at baseline and throughout study period Helps with understanding what we need to control for if randomization did not work as we hoped

Binding (Masking)

• Reduce potential for bias (conscious or subconscious): • Placebos are used to mask • Single blinded study: participants unaware of group assignment Double blinded study: participants and data collectors (researchers and study staff) are unaware of group assignment Treatment is not known for participant or researcher Reduces conscious and subconscious bias in research

• Experimental Studies or Randomized Control Treatments (RCTs)

• Specific Research Inquiry • Inclusion/Exclusion Criteria • Randomization (treatment vs. placebo) • Blinding (Masking)

Participants should be told and understand:

• The study protocol • Randomization process and purpose • Alternative treatments • Potential risks and benefits • Confidentiality • Compensation for time • Who to contact with questions • Right to withdraw

Safety Monitoring

• We must know when to stop the study • Due to harmful or beneficial effects of one treatment arm • Side effects and adverse events (serious complications including death) • Use an Safety Monitoring Board that includes experts outside of the research team or research institution Treatment might work so well: controlled group is being deprived of beneficial treatment that the treatment arm is receiving

Validity of Results

• What impacts the internal and external validity? • Internal (loss to follow-up, lack of randomization, lack of control for known or unknown differences between treatment groups) • External (loss to follow-up, low response rate, narrow inclusion criteria) Internal: measure all known demographic studies and compare between study groups and see things that need to be controlled for in our analysis portion External: not getting a good response rate, think will are sample be representative of the population Narrow inclusion criteria: while we do want to make sure that we are not excluding people, all necessary to answer the question

Ethical Considerations

• When is an experimental study not appropriate? • Causing undue harm • Potentially causing more harm that good • For example, smoking and lung cancer Know that smoking cigarettes in harmful, cannot conduct experiments using cigarettes • Should we randomly assign individuals to different levels of cigarette smoking to see which levels are most associated with lung cancer? • Sometimes an observational study is the best choice in order to protect the participants Observational: better for observing harmful exposures • Randomization • There must be a true uncertainty about which treatment is better Equal chance of treatment and control group Then we might be deprived one half of study to a superior or better treatment, cant run random controlled trials if we know what the results will be, we need to be uncertain to see which group will have better survival rates or decreased symptoms

AIDS and moralism

◊ AIDS has been an especially divisive issue because so many people with AIDS contracted the disease through behavior that is widely regarded as immoral— homosexual acts and intravenous drug use, it is commonly believed that education on how to protect oneself against contracting the virus that causes AIDS may encourage homosexuality and promiscuous sexual behavior in general. ◊ Moralism also enters into discussions of alcohol and drug policy. Libertarians could argue against regulation of alcohol and bans on addictive drugs on the basis that consumption of drugs is private behavior that does not directly hurt others. In fact, however, most citizens accept the validity of such regulation. The power of government to limit drug and alcohol consumption is well established in the United States and corresponds with the tradition of limiting individual behavior for the common good. ◊ While regulation for the common good is valid, trying to legislate morality has often proven to be ineffective, self-defeating, and a threat to liberty, in part because people differ in what they view as moral. ◊ Up to half of the deaths in the United States are preventable, many of them caused by unhealthy behavior. Yet a small fraction of the research funded by the federal government is devoted to understanding why people behave in unhealthy ways and how to encourage them to change these behaviors

OSHA

◊ As an example of the interplay of legislation, agency rule making, and the role of the courts, consider the Occupational Safety and Health Act, passed by Congress in 1970. The legislation stated that "personal injuries and illnesses arising out of work situations impose a substantial burden upon ... interstate commerce," and thus used the federal government's authority over interstate commerce to pass a public health statute. ◊ The law above established the Occupational Safety and Health Administration (OSHA) within the Department of Labor. OSHA was authorized, among other things, to set standards regulating employees' exposure to hazardous substances. Representatives of industry challenged the constitutional authority of Congress to pass the law but were unsuccessful. ◊ One of the substances that OSHA decided to regulate was benzene, which caused a variety of toxic effects among workers in the rubber and petrochemical industries. In 1971, OSHA set a standard limiting benzene exposure to 10 parts per million (ppm) in air, averaged over an 8-hour period. Epidemiologic evidence indicated, however, that exposure to lower concentrations of benzene over time might increase the risk of leukemia, and there was laboratory evidence to support those studies. Therefore, in 1978, OSHA lowered the standard to 1 ppm over an 8-hour period. Representatives of the affected industries appealed the new regulations in court, claiming that evidence that benzene causes leukemia was not sufficiently strong, and that complying with the new standard would be too expensive. The court, in a ruling upheld later by the Supreme Court, agreed that OSHA did not have sufficient evidence to support the need for the new standard and thus had exceeded its authority in issuing the regulation.

What is Public Health?

◊ Charles-Edward A. Winslow, a theoretician and leader of American public health during the first half of the 20th century defined public health in 1920 this way: → The science and art of preventing disease, prolonging life, and promoting physical health and efficiency through organized community efforts for the sanitation of the environment, the control of community infections, the education of the individual in principles of personal hygiene, the organization of medical and nursing services for the early diagnosis and preventive treatment of disease, and development of social machinery which will ensure community- which is a standard of living adequate to health → By the 1980s, public health was taken for granted and most people were unaware of the activities, government expenditures was high, no one was taking about public health, AIDS epidemic broke out, concern about environmental pollution was growing, aging population was demanding increased health services, and social problems such as pregnancy, violence, and substance abuse were common THREE CORE FUNCTIONS OF PUBLIC HEALTH ARE ASSESSMENT, POLICY DEVELOPMENT, AND ASSURANCE

economic impact

◊ Economic impact: most public health measures have a negative one, such as any new proposal for a public health regulation is likely to inspire opposition from some quarter, on the grounds that it might cost jobs, add to the price of the product, or require a tax increase ◊ The difficulty in dealing with the economic impact of public health measures has been illustrated by conflicts with the tobacco industry. Tobacco is clearly harmful to health, causing thousands of deaths and millions of dollars in medical costs annually. Yet, until recently, only mild restrictions and regulations were instituted to discourage use of the product. ◊ With the shift of public opinion against the tobacco industry, together with the industry's need to protect itself against a potentially bankrupting flood of lawsuits by injured smokers, have federal, state, and local governments begun to take serious measures to control smoking. In many circumstances, controversy arises because those who pay for a public health measure are not the ones who benefit. Environmental regulations such as restrictions on timber harvesting in the Pacific Northwest are regularly under attack because they may cost jobs in the lumber industry, although they may preserve jobs in the fishing and tourist industries as well as contribute in the long term to a more stable climate.

Epidemiology

◊ Epidemiology has been called the basis of public health, it is the study of epidemics and focuses on human populations usually starting with an outbreak of disease within the community and epidemiologists look for common exposure or shared characteristics in the people who are sick, seeking the causative factor ◊ Epidemiology also provides the first indications of the nature of the new disease, when AIDS was first recognized in the 1980s, the cause was unknown, epidemiologic research indicated that it was an infectious disease spread through the blood and body fluids so it suggested that the virus was the cause ◊ Epidemiology is also important to prevent the spread of old, well-understood diseases, these specialists are mainstays of local health departments "Shoe leather epidemiology"- track down the source of food-poisoning outbreak and force a restaurant to clean up its kitchen

tragedy of the commons

◊ Government restrictions on behavior that causes indirect harm to others is the way to prevent what Garrett Hardin, in 1968, called the "tragedy of the commons." ◊ Hardin describes a pasture open to all herdsmen in a community. The land can support a limited number of grazing cattle. If each herdsman tries to maximize his gain by keeping as many cattle as possible on the pasture— the commons— the pasture will be overgrazed. The cattle will starve, and the herdsmen will be ruined. The only way for the community to save the pasture is to agree to restrict the freedom of the herdsmen, placing fair and equitable limits on the number of cattle each can keep there. ◊ In the industrialized world of today, the "commons" is the air, water, and other elements of the environment that all people share. Because no individual has the power to control the quality of his or her own personal environment independent of the behavior of his or her neighbors, government action is required to protect these common resources. The United States has made great progress over the past 50 years in cleaning up air and water through federal legislation.

Laws enacted

◊ In a political climate hostile to government, especially the federal government, there was a strong movement in Congress and the Supreme Court to cut government regulation and return more powers to the states. In an early example of the reversal, in 1976 Congress removed the financial penalty for lack of motorcycle helmet laws. By 1980, 27 states had repealed their helmet laws, and motorcycle deaths rose in those states by 38 percent. ◊ The Medicaid program, which has grown enormously expensive since it was established in 1965, has also been a target of Congress, which for some time threatened, without success, to hand it over to the states entirely. ◊ In the 1990s, the U.S. Supreme Court under Chief Justice William Rehnquist began a trend known as the new federalism, which limited Congress's powers and returned authority to the states. For example, in 1995, the Court struck down a law making gun possession within a school zone a federal offense, rejecting the argument that gun possession was a matter of interstate commerce. ◊ In 2001, it decided that the Americans with Disabilities Act could not be enforced against a state, ruling that a woman who was fired from her state job because she had breast cancer could not sue the state of Alabama. ◊ In 2003, Rehnquist "gave up and moved on," writing the majority ruling that state governments could be sued for failing to give their employees the benefits required by the Family and Medical Leave Act. In 2005, the Supreme Court affirmed the priority of federal law over state law in a controversial decision ruling that patients in California could be criminally prosecuted by federal authorities for using marijuana prescribed by a physician according to California's medical marijuana law.

costs and benefits

◊ In times of economic difficulty, people are often unwilling to pay short-term costs in order to obtain a benefit in the long term. In both the fishing and lumber industries, stocks have been dangerously depleted, and there is a risk of killing off all the fish and cutting down all the timber, thereby destroying the industries altogether. Yet few workers in the fishing or lumber industries are willing to voluntarily cut back on their own harvests. ◊ The costs of public health measures are usually much easier to calculate than the benefits. For example, experts may know the cost of reducing smog in Los Angeles to a level that reduces deaths from lung disease by 10 percent. But how do they calculate whether this benefit is worth the cost? It is very difficult to put a dollar value on life and health. Furthermore, it is often difficult to quantify what the risk really is and how to balance it against other risks. People are concerned, for example, about farmers' use of pesticides, which may leave toxic residues on fruits and vegetables. Scientists can estimate the health risks the average person faces by consuming that residue. But fruits and vegetables are an important part of a healthy diet.

Public Health Versus Medical Care

◊ Medicine is focused with individual patients and healing patients who are ill while public health regards the community as a patient, trying to improve the health of the population and preventing illness ◊ Assessment: contributes the diagnostic function, in which public health agency collects, assembles, analyzes, and makes available information ◊ Policy development: doctor's development plan for a sick patient, involves the usage of scientific knowledge to develop a strategic approach to improving the communities health Assurance: equivalent to the doctor's actual treatment of the patient, public health has the responsibility of assuring that the services needed for the protection of public health in the community are available and accessible to everyone including environmental, educational, and basic medical services

Paternalism

◊ Most controversial of public health measures are requirements that restrict people's freedom for the purpose of protecting their own health and safety. Examples of such measures include requirements to wear seat belts when traveling in a car and helmets when riding a motorcycle. ◊ Such restrictions on individual behavior are often criticized as "paternalism." Libertarians, in the words of John Stuart Mill, argue that "the only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others ... In the part [of his conduct] which merely concerns himself, his independence is ... absolute." The one form of paternalism that is generally accepted is that children and young people can be restricted in their behavior on the basis that they are not yet mature enough to make considered judgments as to their own best interests. Thus, there are laws that prevent juveniles from buying tobacco and alcohol, that require them to wear bicycle helmets and seat belts (even where adults are not required to wear them), and that require parental permission to obtain birth control information or an abortion, or to go skydiving.

Philanthropic foundations

◊ Several major philanthropic foundations provide funding to support research or special projects related to public health. For example, the Rockefeller Foundation focuses on world population issues; the Robert Wood Johnson Foundation on providing health care to the poor as well as on AIDS, alcoholism, and drug abuse; the Pew Charitable Trusts on health, AIDS, and drug abuse; the Kaiser Family Foundation on health and public policy; and the Commonwealth Fund also on health and public policy, especially concerning minorities, children, and elderly people. ◊ Consumers groups organized around specific issues have sometimes had a major impact on national or regional policy related to public health. For example, Ralph Nader's traffic safety campaign in the 1960s forced Congress to pass legislation requiring the automobile industry to build safer cars. The Gay Men's Health Crisis played a critical role in the 1980s in starting up community health services for AIDS victims in New York City. Organized community efforts to prevent disease and prolong life must involve all sectors of the community, including providers of healthcare services, local business, community organizations, the media, and the general public.

Legislature and power

◊ Police powers are invoked for three reasons: to prevent a person from harming others; to defend the interests of incompetent persons such as children or the mentally retarded; and, in some cases, to protect a person from harming himself or herself. ◊ In 1905, a precedent was set for the state's police power in the area of health when the Massachusetts legislature ◊ passed a law that required all adults to be vaccinated against smallpox. A man named Jacobson refused to comply and went to court, arguing that the law infringed on his personal liberty. The trial court found that the state was within its power to enforce the law. Jacobson appealed his case all the way to the U.S. Supreme Court. He lost: The Supreme Court upheld the right of the state to restrict an individual's freedom "for the common good." ◊ The public health law has become more complex over the years, but it follows the same pattern. At any level of government, a legislature, perceiving a need, passes a statute. The statute may be challenged in court and the decision of the court may be appealed to higher courts. Generally, on issues of constitutionality, a state court may overturn a local law or court decision, and a federal court may overturn a state law or court decision. Since public health increasingly involves complex technical issues, legislatures at the several levels of government generally set up administrative agencies to perform public health functions. The legislature, recognizing that it lacks the necessary expertise, authorizes these agencies to set rules that define in detail how to accomplish the purpose of the legislation. The courts may then be called on to interpret the authority of the agencies under the laws and to determine whether certain rules or decisions of an agency are within its legal authority

Public health and terrorism

◊ Primary prevention of terrorism acts may be out of domain of public health, but secondary and tertiary prevention are much part of the public health's mission ◊ Crashing of two planes into the World Trade Center triggered emergency response plans designed for secondary prevention- minimizing the damage- and tertiary prevention- providing medical care to those injured in the disaster ◊ Greatest problem with 911 was lack of coordination (only 2092 out of 17,400 people made it out) - plans were not seriously tested because the capacity- including the arrival of numerous volunteers- exceeded the number of injured survivors ◊ Public health was not only concerned with coordinating emergency medical care, but also ensuring the safety of cleanup workers and area residents Public health's importance became more apparent in the aftermath of anthrax mailings which were bioterrorism attacks which did not announce themselves because no alarm bells rang when a few patients showed up in the hospital emergency rooms with hard-to-diagnose illnesses (anthrax was announced in the same way that AIDS appeared which was an outbreak of something new that was reported to public health

Primary, Secondary, and Tertiary prevention

◊ Primary prevention prevents an illness or injury from occurring at all, by preventing exposure to risk factors such as efforts to discourage teenagers from smoking and efforts to encourage smokers to quit ◊ Secondary prevention seeks to minimize the severity of the illness or damage due to the injury-causing event once the event has occurred, example is screening programs are established to detect cancer, early when it is still treatable involves screening programs that help in early detection and diagnosis so individuals disease condition is at a treatable stage ◊ Tertiary prevention seeks to minimize the disability by providing medical care and rehabilitation services All of these interventions were effective in developing traffic safety programs that over the past five decades have reduced the rates of injury from motor vehicle crashes (in this example, the primary focused on preventing crashes from occurring for example building divided highways and installing traffic lights, the secondary included the design of safer automobiles with stronger bumpers, padded dashboards, seatbelts, and air bags; lastly tertiary prevention required the development of emergency medical services including ambulances, 911 calling centers, and trauma centers

Individual liberty

◊ Primary purposes of government is to promote the general welfare; Health and safety, together with economic well-being, are the major factors that contribute to the general welfare. While the government cannot guarantee health and safety for each individual, its role is to provide for maximum health and safety for the community as a whole. One of the central controversies in public health is the extent to which government can and should restrict individual freedom for the purpose of improving the community's health.

Associations

◊ Professional membership organizations, such as the American Public Health Association, the American Medical Association, and the American Nurses Association also are active in lobbying Congress in support of public health issues such as research related to the health effects of smoking. ◊ Organizations that focus on specific diseases, such as the American Heart Association, the American Cancer Society, the Alzheimer's Disease and Related Disorders Association, and the American Diabetes Association, lobby Congress for resources and policies to benefit their causes. They also conduct campaigns to educate the public and may sponsor research concerned with their disease. However, the American Medical Association is also known for its opposition to some public health-related programs such as President Clinton's universal healthcare proposal of 1994 and the possibility of a government-sponsored insurance option in President Obama's 2009 health reform plan (both of which failed).

Statistics in public health

◊ Since public health deals with the health of populations, it depends heavily on statistics (governments collect data on births and death, causes of death, outbreaks of communicable diseases, etc.....)- these numbers are diagnostic tools for informing experts on how healthy or sick a society is and where its weaknesses are ◊ U.S ranks 27th in infant mortality, 26th in life expectancy of men and 28th of women Statistics is used to calculate risks from exposure to environmental chemicals (statistical analysis is an integral part of any epidemiologic study seeking the cause of the disease or a clinical study testing the effectiveness of a new drug)

Public health has a five step process

◊ Public Health has a five step process 1. Define the health problem 2. Identify the risk factors associated with the problem 3. Develop and test community-level interventions to control or prevent the cause of the problem 4. Implement interventions to improve the health of the population 5. Monitor these interventions to assess the effectiveness ◊ Main task of prevention is to develop interventions designed to prevent specific problems that have been identified either through assessment process initiated by a public health agency or through community concern raised by unusual course of events (for example: statistical data may show that a community has a high rate of cancer or series of fatal crashes caused by drunk driving may mobilize a community to demand action to prevent further tragedies) Public health has developed systematic ways of thinking about such problems that facilitate interventions that prevent undesirable health outcomes 1. Define the health problem: is it physical, mental, is it for an individual, whole family, a community or a specific geographic area, Is everyone in the community or belonging to a certain age or ethnic group is infected 2. Why are certain people getting it and others not getting it?, what are the behaviors that the infected people have which is different from the non infected people 3. Developing an effective intervention and test effectiveness of new intervention, initially a small sample and later on a larger sample, takes a very long time to find an effective intervention that can be applied globally 4. Implementation of successful intervention program on a large scale across the nation and sometimes globally or in all the affected places

Biomedical research and environmental health science

◊ Public health and medicine depend on biomedical science and a major proportion of human disease is caused by microorganisms (prevention and control of these diseases in a population require an understanding of how these infectious agents are spread and how they affect the human body) ◊ Biomedical research is important to the understanding and control of new diseases such as AIDS, which has been a major epidemic of the late 20th and early 21st century worldwide; also understanding noninfectious diseases such as cancer and heart disease ◊ Environmental health science is concerned with preventing the spread of disease through water, air and food (much of the great improvements in public health in the united states during the 20th century was due to improved environmental health since most Americans have safe drinking water)- environmental health depends on engineering to design, build, and maintain these systems ◊ Public health is concerned with social and behavioral sciences- people in modern societies are dying of diseases caused by their behavior and the social environment Our society has a greater emphasis on curing rather than preventing a disease- concern about runaway costs, lack of access, and questionable quality of care has lead to an increasing interest in studying the medical care system, its effectiveness, efficiency, and equity leading to a science called health services research

Moral and Religious Opposition

◊ Public health often arouses controversy on moral grounds, most often when it confronts sexual and reproductive issues. AIDS, other sexually transmitted diseases, teenage pregnancy, and low birth-weight babies are major public health problems in the United States. ◊ The public health approach to these problems includes sex education in schools and the provision of contraceptive services, especially condoms. These measures are often vigorously opposed by members of certain religious groups who believe that they promote immoral behavior. Safe and legal abortion to terminate unwanted pregnancy is even more controversial. While there is no question that the safest and healthiest lifestyle is to abstain from sexual activity before marriage and then to be faithful to one's spouse, experience has long shown that preaching morality has limited efficacy in preventing sexually transmitted diseases and unwanted pregnancy.

Public health focus

◊ Public health's focus on prevention makes it more abstract than medicine so achievements are more difficult to consider such as a doctor who cures a sick person has achieved a recognizable benefit and the patient is grateful and public health cannot point to the people who have been spared to illness by its efforts ◊ Estimated that only about 3 percent of the nation's total health spending is done on public health ◊ Life expectancy of Americans has increased from 45 to 75 years over the course of the 20th century, only 5 of those 30 additional years can be attributed to the work of the medical care system- the majority of this gain can be attributed from improvements in public health with better nutrition, housing, sanitation, and occupational safety ◊ Public health is based on science, so a political decision is needed before action can be taken to solve it, for example when the doctor diagnoses a patient's illness and recommends treatment, it is up to the patient to accept or reject doctor's recommendations; also when the patient is a community or a whole country, it is the government- federal, state, and local that is responsible to make the decision to accept or reject the recommendations of public health experts Politics enters public health process as part of policy development function and part of the assurance function (example: since the community will have to pay for the "treatments" usually through taxes, they must decide how much "health" they are willing to fund, also must decide whether they are willing to accept the possible limitations on their freedom that may be needed to improve the communities health

restrictions on individual liberty

◊ Restrictions on individual liberty are sometimes justified on the basis that their purpose is really to protect others, even when the argument is a bit strained. For example, unhelmeted motorcyclists could be a threat to others because of the possibility of their losing control if hit by flying debris. Unhelmeted cyclists and unbelted motorists, severely injured in road accidents, drive up insurance rates for others and in extreme cases may become expensive wards of the state. Alcoholics and drug users bring harm to their families and are a nuisance to their neighbors. ◊ Beauchamp, the philosopher, explores the reasons in his book, The Health of the Republic, arguing that such laws are needed most for behaviors that are common and carry small risks. Consistent use of seat belts, for example, prevents thousands of deaths and injuries in the population as a whole, although the risk people face on any one trip, when they must decide whether to buckle up, is quite small. While each individual's choice to take the risk of driving unbuckled may be rational, society's interest in preventing the thousands of deaths and injuries outweighs the minor inconvenience of obeying the seatbelt law. Beauchamp's argument in favor of limiting individual liberty for the common good is consistent with his view of public health as social justice. Death and disability are collective problems, he says, and collective action is needed to promote the common welfare.

State health departments

◊ Some states have separate agencies for social services, aging, mental health, the environment, and so on. This may cause problems, for example, when the environmental agency makes decisions that impact the population's health without consulting the health agency ◊ State health departments depend heavily on federal money for many programs, and their authority is thus limited by the strings attached to the federal funds. ◊ The state health department coordinates activities of the local agencies and collects and analyzes the data provided by the local agencies. Laboratory services are often provided by state health departments. ◊ State health departments are usually charged with licensing and certification of medical personnel, facilities, and services, with the purpose of maintaining standards of competence and quality of care. People who lack private health insurance are generally the concern of state health departments

States and Medicaid

◊ States have significant— though not total— flexibility in how to administer the Medicaid program, determining eligibility rules for coverage as well as setting payment amounts for the doctors, hospitals, and other providers of medical care. Most states also provide some kind of funding to hospitals to reimburse them for treating uninsured patients who arrive in the emergency room and must be treated. ◊ Funding for state health department activities comes mostly from state taxes and federal grants. Most traditional public health activities at the federal level, other than environmental health, fall under the jurisdiction of the Department of Health and Human Services (HHS).

NIH and FDA

◊ The NIH is the greatest biomedical research complex in the world, with its own research laboratories, most of which are located in Bethesda, Maryland, as well as a program that provides grants to biomedical scientists at universities and research centers throughout the United States. The NIH supports research ranging from basic cellular processes to the physiological errors that underlie human diseases. ◊ The modern FDA was established in 1931, and the current law provides for the agency, in addition to ensuring that the food supply is safe and nutritious, to evaluate all new drugs, food additives and colorings, and certain medical devices, approving them only if they are proven safe and, in the case of drugs, effective. Because FDA regulations affect major segments of the U.S. economy, it is frequently under attack, either for being too restrictive or, when an approved product is found to cause harm, too lenient. Responsibility for environmental health is scattered throughout the federal government, including the CDC's Center for Environmental Health and the NIH's National Institute of Environmental Health Sciences.

Federal State Vs. Authority

◊ The U.S. Constitution does not mention health. Because the Tenth Amendment states that "the powers not delegated to the United States by the Constitution ... are reserved to the States respectively," public health has been a responsibility primarily of the states. ◊ Constitution: It gives the federal government authority to regulate interstate commerce and to "collect taxes ... to pay the debts and provide for the common defense and the general welfare." These powers are the basis for the federal role in public health. ◊ The interstate commerce provision, for example, justifies the activities of the Food and Drug Administration (FDA), which oversees extensive federal regulation of foods, drugs, medical devices, and cosmetics, most of which are distributed across state lines. ◊ The power to tax and spend is a way for the federal government to achieve goals that it may lack the authority to achieve directly. It can provide funds to the states subject to certain requirements. For example, in 1967 the federal government mandated that, as a precondition for receiving highway construction funds, states must pass laws requiring motorcyclists to wear helmets. ◊ The mandate was demonstrated by the fact that, by 1975, 47 states had passed such laws, with the result that motorcyclist deaths declined by 30 percent in these states. The federal government provides 50 to 80 percent of the funding for Medicaid. States and counties administer the Medicaid program, providing the remaining funds, and must follow the guidelines established by Congress.

Another approach for designing intervention is to think of an illness or injury as a result of a chain of causation, involving an agent, host, and the environment

◊ The agent may be a disease-causing bacterium or virus, the host is a susceptible human being, and the environment includes the means of transmission by which the agent reaches the host, which may be contaminated by food, water, air, or it may be another human being who is infected (prevention for this is accomplished by interrupting the chain of causation at any step: rendering is a potential host unsusceptible through immunization that can interrupt the chain) The chain of causation model can be used for other illness or injuries such as suicide is the second leading cause of death in the group of age 15-24 (in applying model to prevention of youth suicide, the host is the susceptible young person, the agent is most often the gun or overdose of pills, and the environment includes the young person's whole social environment, including family, school, and the media

Sciences of public health

◊ The institute of Medicine says that "public health is a coalition of professions united by their shared mission" as well as by "their focus on disease prevention and health promotion; their prospective approach in contrast to the reactive focus of therapeutic medicine and their common science, epidemiology ◊ Epidemiology and statistics are the basis for assessment functions of public health, including collection and analysis of information Assessment and policy development need an understanding of the causes of health problems in the community, an understanding that depends on biomedical sciences, social, and behavioral sciences, and environmental sciences

County local health department

◊ The most common local agency is the county health department. A large city may have its own municipal health department, and rural areas may be served by multi county health departments. ◊ Local health departments have the day-to-day responsibility for public health matters in their jurisdiction. These include collecting health statistics; conducting communicable disease control programs; providing screening and immunizations; providing health education services and chronic disease control programs; conducting sanitation, sanitary engineering, and inspection programs; running school health programs; and delivering maternal and child health services and public health nursing services. ◊ A portion of the local health budget usually comes from local property and sales taxes, and from fees that the department charges for some services. Some states provide the bulk of funding for local health departments while others provide very little. The federal government may fund some local health department activities directly, or federal funds may be passed on from the states. The states have the primary constitutional responsibility and authority for the protection of the health, safety, and general welfare of the population, and much of this responsibility falls on state health departments.

CDC

◊ The predominant agencies are the Centers for Disease Control and Prevention (CDC), the National Institutes of Health (NIH), and the FDA. The Surgeon General is the nation's leading spokesperson on matters of public health. ◊ The CDC is the main assessment and epidemiologic agency for the nation. The mission of the CDC is, as its name implies, to control and prevent human diseases. Traditionally, the CDC focused on infectious diseases and was therefore crisis-oriented. In contrast, the NIH holds the longer view of a research agency. The CDC is staffed with epidemiologists who travel throughout the country and the world to detect outbreaks of disease, to track down the causes of epidemics, and to halt their spread. ◊ The CDC issues a weekly publication called Morbidity and Mortality Weekly Report (MMWR), which is widely distributed in print and electronically via the Internet. MMWR reports on timely public health topics that the CDC deals with, such as outbreaks of infectious diseases and new environmental and behavioral health hazards. The first published report that heralded the onset of the AIDS epidemic appeared in MMWR on June 4, 1981.12 The CDC's journal Emerging Infectious Diseases, published in print and online, discusses new infectious disease threats that occur naturally as well as potential bioterrorist threats.

Agencies

◊ The prime agency for the environment is the Environmental Protection Agency (EPA), established in 1970 to carry out programs dealing with water pollution, air pollution, toxic substances control, and other issues of environmental contamination. The EPA is one of the most controversial federal public health agencies. It has often been attacked by Congress and its policies were often watered down by the George W. Bush White House. ◊ The Department of Agriculture also oversees food and nutrition programs, including food stamps and school lunches. The Department of Education supervises health education and school health and safety programs. ◊ Among the responsibilities of the Department of Transportation is traffic safety, the purview of the National Highway Traffic Safety Administration, which has had great success in reducing deaths caused by motor vehicles. The Department of Labor has OSHA, which is concerned with occupational health and prevention of occupational injury. The Department of Veterans Affairs administers its own health and medical services. The Department of Defense, which provides medical care for the armed forces, has long had to deal with public health concerns relating to threats from infectious diseases in foreign climates as well as health effects from toxic chemicals and radiation. The Department of Homeland Security was created in 2003 to protect the public from acts of terrorism, natural disasters, and other emergencies.

Cross-sectional studies

◊ The relationship between exposure and disease prevalence that define a population at a single point of time ◊ Commonly selected without exposure without regards to exposure and disease status ◊ Usually measure the disease prevalence because they look at the population within a single point of time in relation to the exposure prevalence ◊ Current disease status is usually examined to current exposure level ◊ Exposures and outcomes are assessed at one point of time ◊ Commonly performed using large cross selection data sets that are collected on samples on one particular point of time Best for generating hypotheses

Introduction in Chapter 1

◊ Tuberculosis was the single largest cause of death in the mid-19th century (cholera, typhoid, and smallpox also swept through the communities) ◊ Number of reasons prove why people's lives are healthier today than they were 150 years ago: cleaner water, air, food, disposal of sewage, better nutrition, and more knowledge on healthy versus unhealthy behaviors (these factors fall into the domain of public health) ◊ Public health has improved since the 19th century because the general state of people's health is now much better than it previously was ◊ The measures that people take as a society to bring about and maintain that improvement is noted as public health Laws regulating people's behaviors prevent them from injuring from one another, laws requiring immunization of school-aged children prevent the spread of infectious diseases

Political interference with science

◊ While there are legitimate differences of opinion on how to weigh the competing interests in making policy that affects public health, these decisions should be informed by science to the extent possible. ◊ One example cited by the UCS report was pressure on the Centers for Disease Control and Prevention (CDC) to promote abstinence-only programs for preventing teen pregnancy. The CDC was required to remove from its Web site information on "Programs that Work," five sex education programs for teenagers that had been found effective in scientific studies. Similarly, the CDC replaced information on the effectiveness of condoms in preventing the spread of HIV/ AIDS with a document that emphasized condom failure rates and the effectiveness of abstinence. While there is no dispute that abstinence is the most effective way to prevent pregnancy and HIV transmission, scientific studies have found abstinence-only programs to be ineffective.