Introduction to Epidemiology
communicable disease
a disease that is spread from one host to another
experimental and observational
Epidemiologic studies fall into these two categories:
certain
A case definition may have several sets of criteria, depending on how ________ the diagnosis is. For example, during an investigation of a possible case or outbreak of measles, a person with a fever and rash might be classified as having a suspected, probable, or confirmed case of measles, depending on what evidence of measles is present.
endemic
(adj.) native or confined to a particular region or people; characteristic of or prevalent in a field
laboratory
A case might be classified as suspected or probable while waiting for the ___________ results to become available. Once the laboratory provides the report, the case can be reclassified as either confirmed or "not a case," depending on the laboratory results. In the midst of a large outbreak of a disease caused by a known agent, some cases may be permanently classified as suspected or probable because officials may feel that running laboratory tests on every patient with a consistent clinical picture and a history of exposure (e.g., chickenpox) is unnecessary and even wasteful. Case definitions should not rely on laboratory culture results alone, since organisms are sometimes present without causing disease.
non-communicable disease
A disease that cannot be spread from person to person
retrospective cohort study
A research study in which the educational, family, police, and medical records of groups of individuals who are alike in many ways but differ by a certain characteristic (for example, female nurses who smoke and those who do not smoke) are compared for a particular outcome (such as lung cancer). This is also called a historic cohort study.
Case-control study
A type of epidemiologic study where a group of individuals with the diseases, referred to as cases, are compared to individuals without the disease, referred to as controls
World War 2
Although epidemiology as a discipline has blossomed since _______ ____ #, epidemiological thinking has been traced from Hippocrates through John Graunt, William Farr, John Snow, and others. The contributions of some of these early and more recent thinkers are described below.
retrospective cohort study, prospective cohort study
An alternative type of cohort study is a _________ ______ _____. In this type of study both the exposure and the outcomes have already occurred. Just as in a ________ _____ study, the investigator calculates and compares rates of disease in the exposed and unexposed groups. These types of studies are commonly used in investigations of disease in groups of easily identified people such as workers at a particular factory or attendees at a wedding. For example, this type of study was used to determine the source of infection of cyclosporiasis, a parasitic disease that caused an outbreak among members of a residential facility in Pennsylvania in 2004.The investigation indicated that consumption of snow peas was implicated as the vehicle of the cyclosporiasis outbreak.
descriptive, descriptive, analytic
As noted earlier, _________ epidemiology can identify patterns among cases and in populations by time, place and person. From these observations, epidemiologists develop hypotheses about the causes of these patterns and about the factors that increase risk of disease. In other words, epidemiologists can use __________ epidemiology to generate hypotheses, but only rarely to test those hypotheses. For that, epidemiologists must turn to ________ epidemiology.
planning
As noted, one of the basic tasks in public health is identifying and counting cases. These counts, usually derived from case reports submitted by health-care workers and laboratories to the health department, allow public health officials to determine the extent and patterns of disease occurrence by time, place, and person. They may also indicate clusters or outbreaks of disease in the community. Counts are also valuable for health _________. For example, a health official might use counts (i.e., numbers) to plan how many infection control isolation units or doses of vaccine may be needed.
counts, divides, compares
As with all scientific endeavors, the practice of epidemiology relies on a systematic approach. In very simple terms, the epidemiologist: - _______ cases or health events, and describes them in terms of time, place, and person; - _______ the number of cases by an appropriate denominator to calculate rates; and - _________ these rates over time or for different groups of people.
case definition (before counting cases)
Before counting cases, however, the epidemiologist must decide what a case is. This is done by developing a....
1990, September 11, biologic warfare, bioterrorism
Beginning in the ####s and accelerating after the terrorist attacks of _________ ##, 2001, epidemiologists have had to consider not only natural transmission of infectious organisms but also deliberate spread through b________ _______ and ____________.
Too broad. Most persons with cough and fever returning from Toronto, China, etc., are more likely to have upper respiratory infections than SARS.
CDC Preliminary Case Definition for Severe Acute Respiratory Syndrome (SARS) — March 21, 2003 Suspected case Respiratory illness of unknown etiology with onset since February 1, 2003, and the following criteria: - Documented temperature > 100.4°F (>38.0°C) - One or more symptoms with respiratory illness (e.g., cough, shortness of breath, difficulty breathing, or radiographic findings of pneumonia or acute respiratory distress syndrome) - Close contact *within 10 days of onset of symptoms with a person under investigation for or suspected of having SARS or travel within 10 days of onset of symptoms to an area with documented transmission of SARS as defined by the World Health Organization (WHO) * Defined as having cared for, having lived with, or having had direct contact with respiratory secretions and/or body fluids of a person suspected of having SARS. Explain how this case definition would address deciding who should be quarantined
Third criterion may be limiting because patient may not be aware of close contact
CDC Preliminary Case Definition for Severe Acute Respiratory Syndrome (SARS) — March 21, 2003 Suspected case Respiratory illness of unknown etiology with onset since February 1, 2003, and the following criteria: - Documented temperature > 100.4°F (>38.0°C) - One or more symptoms with respiratory illness (e.g., cough, shortness of breath, difficulty breathing, or radiographic findings of pneumonia or acute respiratory distress syndrome) - Close contact *within 10 days of onset of symptoms with a person under investigation for or suspected of having SARS or travel within 10 days of onset of symptoms to an area with documented transmission of SARS as defined by the World Health Organization (WHO) * Defined as having cared for, having lived with, or having had direct contact with respiratory secretions and/or body fluids of a person suspected of having SARS. Explain how this case definition would address diagnosing and caring for individual patients
Criteria do not require sophisticated evaluation or testing, so can be used anywhere in the world
CDC Preliminary Case Definition for Severe Acute Respiratory Syndrome (SARS) — March 21, 2003 Suspected case Respiratory illness of unknown etiology with onset since February 1, 2003, and the following criteria: - Documented temperature > 100.4°F (>38.0°C) - One or more symptoms with respiratory illness (e.g., cough, shortness of breath, difficulty breathing, or radiographic findings of pneumonia or acute respiratory distress syndrome) - Close contact *within 10 days of onset of symptoms with a person under investigation for or suspected of having SARS or travel within 10 days of onset of symptoms to an area with documented transmission of SARS as defined by the World Health Organization (WHO) * Defined as having cared for, having lived with, or having had direct contact with respiratory secretions and/or body fluids of a person suspected of having SARS. Explain how this case definition would address doing research to identify the cause of the disease
Probably reasonable
CDC Preliminary Case Definition for Severe Acute Respiratory Syndrome (SARS) — March 21, 2003 Suspected case Respiratory illness of unknown etiology with onset since February 1, 2003, and the following criteria: - Documented temperature > 100.4°F (>38.0°C) - One or more symptoms with respiratory illness (e.g., cough, shortness of breath, difficulty breathing, or radiographic findings of pneumonia or acute respiratory distress syndrome) - Close contact *within 10 days of onset of symptoms with a person under investigation for or suspected of having SARS or travel within 10 days of onset of symptoms to an area with documented transmission of SARS as defined by the World Health Organization (WHO) * Defined as having cared for, having lived with, or having had direct contact with respiratory secretions and/or body fluids of a person suspected of having SARS. Explain how this case definition would address tracking the occurrence of disease.
descriptive epidemiology
Characterizing health events by time, place, and person are activities of... The aspect of epidemiology concerned with organizing and summarizing health-related data according to time, place, and person - involves the study of disease incidence and distribution by TIME, PLACE, and PERSON - includes the calculation of rates and identification of parts of the population at higher risk than others
descriptive
Clusters or outbreaks of disease frequently are investigated initially with ____________ epidemiology.
morbidity, mortality
Common Types of Reports Used to Collect Data in Public Health Surveillance: ___________ and ____________ reports are common sources of surveillance data for local and state health departments. These reports generally are submitted by health-care providers, infection control practitioners, or laboratories that are required to notify the health department of any patient with a reportable disease such as pertussis, meningococcal meningitis, or AIDS. Other sources of health-related data that are used for surveillance include reports from investigations of individual cases and disease clusters, public health program data such as immunization coverage in a community, disease registries, and health surveys.
determinants (food histories)
Compare food histories between persons with Staphylococcus food poisoning and those without. Would this describe distribution, determinants, or application?
determinants (brain cancer)
Compare frequency of brain cancer among anatomists with frequency in general population. Would this describe distribution, determinants, or application?
public health surveillance (comparing persons)
Comparing persons with symptomatic versus asymptomatic Chlamydia infection to identify predictors Would this match with public health surveillance, field investigation, analytic studies, evaluation, linkages, and policy development?
limitations, eccentricities, extent, patterns, description, groups, high
Compiling and analyzing data by time, place, and person is desirable for several reasons. 1) by looking at the data carefully, the epidemiologist becomes very familiar with the data. He or she can see what the data can or cannot reveal based on the variables available, its _________ (for example, the number of records with missing information for each important variable), and its ______________ (for example, all cases range in age from 2 months to 6 years, plus one 17-year-old.). 2) the epidemiologist learns the ________ and ________ of the public health problem being investigated — which months, which neighborhoods, and which groups of people have the most and least cases. 3) the epidemiologist creates a detailed _________ of the health of a population that can be easily communicated with tables, graphs, and maps. 4) the epidemiologist can identify areas or ________ within the population that have (low/high) rates of disease. This information in turn provides important clues to the causes of the disease, and these clues can be turned into testable hypotheses.
analytic studies (conducting analysis)
Conducting an analysis of patient flow at the public health clinic to determine waiting times for clinic patients Would this match with public health surveillance, field investigation, analytic studies, evaluation, linkages, and policy development?
comparison, control group
Consider a large outbreak of hepatitis A that occurred in Pennsylvania in 2003. Investigators found almost all of the case-patients had eaten at a particular restaurant during the 2-6 weeks (i.e., the typical incubation period for hepatitis A) before onset of illness. While the investigators were able to narrow down their hypotheses to the restaurant and were able to exclude the food preparers and servers as the source, they did not know which particular food may have been contaminated. The investigators asked the case-patients which restaurant foods they had eaten, but that only indicated which foods were popular. The investigators, therefore, also enrolled and interviewed a __________ or ______ ________ — a group of persons who had eaten at the restaurant during the same period but who did not get sick. Of 133 items on the restaurant's menu, the most striking difference between the case and control groups was in the proportion that ate salsa (94% of case-patients ate, compared with 39% of controls). Further investigation of the ingredients in the salsa implicated green onions as the source of infection. Shortly thereafter, the Food and Drug Administration issued an advisory to the public about green onions and risk of hepatitis A. This action was in direct response to the convincing results of the analytic epidemiology, which compared the exposure history of case-patients with that of an appropriate comparison group.
place
Describing the occurrence of disease by _____ provides insight into the geographic extent of the problem and its geographic variation. Characterization by place refers not only to place of residence but to any geographic location relevant to disease occurrence. Such locations include place of diagnosis or report, birthplace, site of employment, school district, hospital unit, or recent travel destinations. The unit may be as large as a continent or country or as small as a street address, hospital wing, or operating room. Sometimes place refers not to a specific location at all but to a place category such as urban or rural, domestic or foreign, and institutional or noninstitutional.
time, place, and person
Descriptive epidemiology covers....
public health surveillance (developing guidelines)
Developing guidelines/criteria about which patients coming to the clinic should be screened (tested) for Chlamydia infection Would this match with public health surveillance, field investigation, analytic studies, evaluation, linkages, and policy development?
seasonality
Disease occurrence can be graphed by week or month over the course of a year or more to show this type of pattern, if any. Some diseases such as influenza and West Nile infection are known to have characteristic ________ distributions. These patterns may suggest hypotheses about how the infection is transmitted, what behavioral factors increase risk, and other possible contributors to the disease or condition.
Circa 400 BC
During this time period, Hippocrates attempted to explain disease occurrence from a RATIONAL rather than a supernatural viewpoint. In his essay entitled "On Airs, Waters, and Places," he suggested that ENVIRONMENTAL and HOST FACTORS such as behaviors might INFLUENCE the development of DISEASE.
1662
During this time, John Graunt published a landmark analysis of mortality data. This publication was the first to quantify patterns of birth, death, and disease occurrence, noting disparities between males and females, high infant mortality, urban/rural differences, and seasonal variations.
1800
During this time, William Farr built upon Graunt's work by systematically collecting and analyzing BRITAIN'S MORTALITY STATISTICS. He is considered the father of MODERN VITAL STATISTICS and SURVEILLANCE, developed many of the basic practices used today in vital statistics and DISEASE CLASSIFICATION. He concentrated his efforts on collecting vital statistics, assembling and evaluating those data, and reporting to responsible health authorities and the general public.
determinants (fill in the blank)
Epidemiologists assume that illness does not occur randomly in a population, but happens only when the right accumulation of risk factors or ____________ exists in an individual
study
Epidemiology is DATA-DRIVEN and relies on a SYSTEMATIC and UNBIASED APPROACH to the collection, analysis, and interpretation of DATA. Basic epidemiologic methods tend to rely on careful OBSERVATION and use of valid COMPARISON GROUPS to assess whether what was observed, such as the number of cases of disease in a particular area during a particular time period or the frequency of an exposure among persons with disease, differs from what might be expected. However, epidemiology also draws on methods from other scientific fields, including biostatistics and informatics, with biologic, economic, social, and behavioral sciences. First, epidemiology is a QUANTITATIVE DISCIPLINE that relies on a working knowledge of probability, statistics, and sound RESEARCH METHODS. Second, epidemiology is a method of CAUSAL REASONING based on developing and TESTING HYPOTHESES grounded in such scientific fields as biology, behavioral sciences, physics, and ergonomics to explain health-related behaviors, states, and events. However, epidemiology is not just a research activity but an integral component of public health, providing the foundation for directing practical and appropriate public health action based on this science and causal reasoning. What part of the definition of epidemiology does this explain?
distribution
Epidemiology is concerned with the FREQUENCY and PATTERN of health events in a population What part of the definition of epidemiology does this explain?
application
Epidemiology is not just "the study of" health in a population; it also involves applying the knowledge gained by the studies to community-based practice. Like the practice of medicine, the practice of epidemiology is both a science and an art. To make the proper diagnosis and prescribe appropriate treatment for a patient, the clinician COMBINES medical (scientific) KNOWLEDGE WITH EXPERIENCE, clinical judgment, and understanding of the patient. Similarly, the epidemiologist uses the scientific methods of descriptive and analytic epidemiology as well as experience, epidemiological judgment, and understanding of local conditions in "diagnosing" the health of a community and proposing appropriate, practical, and acceptable public health interventions to control and prevent disease in the community. What part of the definition of epidemiology does this explain?
epidemics, endemic, non-communicable, chronic diseases, genetic, health-related states or events
Epidemiology was originally focused exclusively on __________ of communicable diseases but was subsequently expanded to address __________ communicable diseases and ____-___________ infectious diseases. By the middle of the 20th Century, additional epidemiological methods had been developed and applied to _________ _________, injuries, birth defects, maternal-child health, occupational health, and environmental health. Then epidemiologists began to look at behaviors related to health and well-being, such as amount of exercise and seat belt use. Now, with the recent explosion in molecular methods, epidemiologists can make important strides in examining ________ markers of disease risk. Indeed, the term ________-________ ______ or _______ may be seen as anything that affects the well-being of a population. Nonetheless, many epidemiologists still use the term "disease" as shorthand for the wide range of health-related states and events that are studied.
2500
Epidemiology's roots are nearly #### years old.
compares, analytic epidemiology
Finally, to determine whether this rate is greater than what one would normally expect, and if so to identify factors contributing to this increase, the epidemiologist ___________ the rate from this population to the rate in an appropriate comparison group, using _______ __________ techniques.
specified populations
For example, when a patient with diarrheal disease presents, both are interested in establishing the correct diagnosis. However, while the CLINICIAN usually focuses on treating and caring for the INDIVIDUAL, while the EPIDEMIOLOGIST focuses on identifying the exposure or SOURCE that CAUSED the illness; the number of other persons who may have been similarly exposed; the potential for further spread in the community; and interventions to prevent additional cases or recurrences. What part of the definition of epidemiology does this explain?
day of the week or time of the day
For some conditions, displaying data by _____ ___ ___ ____ ___ ____ ___ ___ _____ may be informative. Analysis at these shorter time periods is particularly appropriate for conditions related to occupational or environmental exposures that tend to occur at regularly scheduled intervals. For example, farm tractor fatalities are displayed by this.
cross-sectional, risk factors
From an analytic viewpoint the _____________ study is weaker than either a cohort or a case-control study because a this type of study usually cannot disentangle ____ ______ for occurrence of disease (incidence) from risk factors for survival with the disease. (Incidence and prevalence are discussed in more detail in Lesson 3.) On the other hand, a cross-sectional study is a perfectly fine tool for descriptive epidemiology purposes. Cross-sectional studies are used routinely to document the prevalence in a community of health behaviors (prevalence of smoking), health states (prevalence of vaccination against measles), and health outcomes, particularly chronic conditions (hypertension, diabetes).
distribution (graph # of cases)
Graph the number of cases of congenital syphilis by year for the country. Would this describe distribution, determinants, or application?
secular (long-term) trends
Graphing the annual cases or rate of a disease over a period of years shows this type of trend in the occurrence of the disease. Health officials use these graphs to assess the prevailing direction of disease occurrence (increasing, decreasing, or essentially flat), help them evaluate programs or make policy decisions, infer what caused an increase or decrease in the occurrence of a disease (particularly if the graph indicates when related events took place), and use past trends as a predictor of future incidence of disease.
Hippocrates
In Circa 400 BC, he attempted to explain disease occurrence from a RATIONAL rather than a supernatural viewpoint. In his essay entitled "On Airs, Waters, and Places," he suggested that ENVIRONMENTAL and HOST FACTORS such as behaviors might INFLUENCE the development of DISEASE.
public health surveillance (interviewing persons)
Interviewing persons infected with Chlamydia to identify their sex partners Would this match with public health surveillance, field investigation, analytic studies, evaluation, linkages, and policy development?
analytic, experimental, observational, observational cohort, observational case-control, cross-sectional
In summary, the purpose of an ______ study in epidemiology is to identify and quantify the relationship between an exposure and a health outcome. The hallmark of such a study is the presence of at least two groups, one of which serves as a comparison group. In an __________ study, the investigator determines the exposure for the study subjects; in an ____________ study, the subjects are exposed under more natural conditions. In an __________ _______ study, subjects are enrolled or grouped on the basis of their exposure, then are followed to document occurrence of disease. Differences in disease rates between the exposed and unexposed groups lead investigators to conclude that exposure is associated with disease. In an __________ _________ study, subjects are enrolled according to whether they have the disease or not, then are questioned or tested to determine their prior exposure. Differences in exposure prevalence between the case and control groups allow investigators to conclude that the exposure is associated with the disease. ______________ studies measure exposure and disease status at the same time, and are better suited to descriptive epidemiology than causation.
1980
In the ####s, epidemiology was extended to the studies of injuries and violence.
molecular, genetic, infectious
In the 1990s, the related fields of m_______ and ________ epidemiology (expansion of epidemiology to look at specific pathways, molecules and genes that influence risk of developing disease) took root. Meanwhile, infectious diseases continued to challenge epidemiologists as new _________ agents emerged (Ebola virus, Human Immunodeficiency virus (HIV)/ Acquired Immunodeficiency Syndrome (AIDS)), were identified (Legionella, Severe Acute Respiratory Syndrome (SARS)), or changed (drug-resistant Mycobacterium tuberculosis, Avian influenza).
disease, acute infectious, noninfectious
In the mid- and late-1800s, epidemiological methods began to be applied in the investigation of _________ occurrence. At that time, most investigators focused on ______ ________ diseases.In the 1930s and 1940s, epidemiologists extended their methods to _______ diseases.
Lambeth, Southwark and Vauxhall, Thames, Lambeth, upstream, higher, consistent, districts, Southwark and Vauxhall, time, place, person, hypothesis, study, water
John Snow #2: Because John Snow's work illustrates the classic sequence from descriptive epidemiology to hypothesis generation to hypothesis testing (analytic epidemiology) to application, two of his investigations will be described in detail. 1) Snow's second investigation reexamined data from the 1854 cholera outbreak in London. During a cholera epidemic a few years earlier, Snow had noted that districts with the highest death rates were serviced by two water companies: the __________ Company and the ________ ____ ________ Company. At that time, both companies obtained water from the _______ River at intake points that were downstream from London and thus susceptible to contamination from London sewage, which was discharged directly into the Thames. To avoid contamination by London sewage, in 1852 the ________ Company moved its intake water works to a site on the Thames well (downstream/upstream) from London. Over a 7-week period during the summer of 1854, Snow compared cholera mortality among districts that received water from one or the other or both water companies. The results are shown in Table 1.1. 2) The data in Table 1.1 show that the cholera death rate was more than 5 times (lower/higher) in districts served only by the Southwark and Vauxhall Company (intake downstream from London) than in those served only by the Lambeth Company (intake upstream from London). Interestingly, the mortality rate in districts supplied by both companies fell between the rates for districts served exclusively by either company. These data were (consistent/inconsistent) with the hypothesis that water obtained from the Thames below London was a source of cholera. Alternatively, the populations supplied by the two companies may have differed on other factors that affected their risk of cholera. 3) To test his water supply hypothesis, Snow focused on the ________ served by both companies, because the households within a district were generally comparable except for the water supply company. In these districts, Snow identified the water supply company for every house in which a death from cholera had occurred during the 7-week period. Table 1.2 shows his findings. 4) This study, demonstrating a higher death rate from cholera among households served by the ______ ___ ______ Company in the mixed districts, added support to Snow's hypothesis. It also established the sequence of steps used by current-day epidemiologists to investigate outbreaks of disease. Based on a characterization of the cases and population at risk by _____, ______, and ________, Snow developed a testable ____________. He then tested his hypothesis with a more rigorously designed _______, ensuring that the groups to be compared were comparable. After this study, efforts to control the epidemic were directed at changing the location of the water intake of the Southwark and Vauxhall Company to avoid sources of contamination. Thus, with no knowledge of the existence of microorganisms, Snow demonstrated through epidemiological studies that _____ could serve as a vehicle for transmitting cholera and that epidemiological information could be used to direct prompt and appropriate public health action.
Golden Square of London, spot map, water, distribution, cholera, pumps, A, brewery, well, uncontaminated, Broad Street, John Snow Pub
John Snow Study #1: Because John Snow's work illustrates the classic sequence from descriptive epidemiology to hypothesis generation to hypothesis testing (analytic epidemiology) to application, two of his investigations will be described in detail. 1) Snow conducted one of his now famous studies in 1854 when an epidemic of cholera erupted in the ________ _____ of ________. He began his investigation by determining where in this area persons with cholera lived and worked. He marked each residence on a map of the area, as shown in Figure 1.1. Today, this type of map, showing the geographic distribution of cases, is called a ____ ____. 2) Because Snow believed that ______ was a source of infection for cholera, he marked the location of water pumps on his spot map, then looked for a relationship between the ____________ of households with cases of ________ and the location of ______. He noticed that more case households clustered around Pump A, the Broad Street pump, than around Pump B or C. When he questioned residents who lived in the Golden Square area, he was told that they avoided Pump B because it was grossly contaminated, and that Pump C was located too inconveniently for most of them. From this information, Snow concluded that the Broad Street pump (Pump _____) was the primary source of water and the most likely source of infection for most persons with cholera in the Golden Square area. He noted with curiosity, however, that no cases of cholera had occurred in a two-block area just to the east of the Broad Street pump. Upon investigating, Snow found a _________ located there with a deep ______ on the premises. Brewery workers got their water from this well, and also received a daily portion of malt liquor. Access to these (contaminated/uncontaminated) rations could explain why none of the brewery's employees contracted cholera. 3) To confirm that the _______ _______ pump was the source of the epidemic, Snow gathered information on where persons with cholera had obtained their water. Consumption of water from the Broad Street pump was the one common factor among the cholera patients. After Snow presented his findings to municipal officials, the handle of the pump was removed and the outbreak ended. The site of the pump is now marked by a plaque mounted on the wall outside of the appropriately named ______ _____ _____.
Many case definitions, such as that shown for listeriosis, require laboratory confirmation. This is not always necessary, however; in fact, some diseases have no distinctive laboratory findings. Kawasaki syndrome, for example, is a childhood illness with fever and rash that has no known cause and no specifically distinctive laboratory findings. Notice that its case definition (see box below) is based on the presence of fever, at least four of five specified clinical findings, and the lack of a more reasonable explanation. It is missing laboratory confirmation since Kawasaki syndrome has no distinctive laboratory findings.
Kawasaki Syndrome — Case Definition Clinical description: A febrile illness of greater than or equal to 5 days' duration, with at least four of the five following physical findings and no other more reasonable explanation for the observed clinical findings: - Bilateral conjunctival injection - Oral changes (erythema of lips or oropharynx, strawberry tongue, or fissuring of the lips) - Peripheral extremity changes (edema, erythema, or generalized or periungual desquamation) - Rash - Cervical lymphadenopathy (at least one lymph node greater than or equal to 1.5 cm in diameter) Laboratory criteria for diagnosis: None Case classification: Confirmed: a case that meets the clinical case definition Comment: If fever disappears after intravenous gamma globulin therapy is started, fever may be of less than 5 days' duration, and the clinical case definition may still be met. What is something peculiar about this case?
comparison group
Key feature of analytic epidemiology =
Both the national surveillance case definition and the outbreak case definition require a clinically compatible illness and laboratory confirmation of Listeria monocytogenes from a normally sterile site, but the outbreak case definition adds restrictions on time and place, reflecting the scope of the outbreak.
Listeriosis — Surveillance Case Definition Clinical description: Infection caused by Listeria monocytogenes, which may produce any of several clinical syndromes, including stillbirth, listeriosis of the newborn, meningitis, bacteriemia, or localized infections Laboratory criteria for diagnosis: Isolation of L. monocytogenes from a normally sterile site (e.g., blood or cerebrospinal fluid or, less commonly, joint, pleural, or pericardial fluid) Case classification: Confirmed: a clinically compatible case that is laboratory confirmed Listeriosis — Outbreak Investigation Case definition: Clinically compatible illness with L. monocytogenes isolated - From a normally sterile site - In a resident of Winston-Salem, North Carolina - With onset between October 24, 2000 and January 4, 2001 What is a similarity and difference between the surveillance and outbreak investigation case definition?
World War 2, 1950, 1970, 1980, making individual decisions
Many individuals may not realize that they use epidemiological information to make daily decisions affecting their health. When persons decide to quit smoking, climb the stairs rather than wait for an elevator, eat a salad rather than a cheeseburger with fries for lunch, or use a condom, they may be influenced, consciously or unconsciously, by epidemiologists' assessment of risk. Since ______ ___ #, epidemiologists have provided information related to all those decisions. In the ####s, epidemiologists reported the increased risk of lung cancer among smokers. In the ####s, epidemiologists documented the role of exercise and proper diet in reducing the risk of heart disease. In the mid-####s, epidemiologists identified the increased risk of HIV infection associated with certain sexual and drug-related behaviors. These and hundreds of other epidemiological findings are directly relevant to the choices people make every day, choices that affect their health over a lifetime. What use of epidemiology does this describe?
distribution (hazardous waste site)
Mark on a map the residences of all children born with birth defects within 2 miles of a hazardous waste site. Would this describe distribution, determinants, or application?
field investigation (meeting with directors)
Meeting with directors of family planning clinics and college health clinics to discuss Chlamydia testing and reporting Would this match with public health surveillance, field investigation, analytic studies, evaluation, linkages, and policy development?
communicable, electronic reporting
Modern Public Health Surveillance: While public health surveillance traditionally has focused on ___________ diseases, surveillance systems now exist that target injuries, chronic diseases, genetic and birth defects, occupational and potentially environmentally-related diseases, and health behaviors. Since September 11, 2001, a variety of systems that rely on __________ _________ have been developed, including those that report daily emergency department visits, sales of over-the-counter medicines, and worker absenteeism. Because epidemiologists are likely to be called upon to design and use these and other new surveillance systems, an epidemiologist's core competencies must include design of DATA collection instruments, DATA management, descriptive methods and graphing, interpretation of DATA, and SCIENTIFIC writing and PRESENTATION.
Searching for causes
Much epidemiological research is devoted to searching for CAUSAL FACTORS that influence one's risk of disease. Ideally, the goal is to identify a cause so that appropriate public health action might be taken. One can argue that epidemiology can never prove a causal relationship between an exposure and a disease, since much of epidemiology is based on ecologic reasoning. Nevertheless, epidemiology often provides enough information to support effective action. Examples date from the removal of the handle from the Broad St. pump following John Snow's investigation of cholera in the Golden Square area of London in 1854, to the withdrawal of a vaccine against rotavirus in 1999 after epidemiologists found that it increased the risk of intussusception, a potentially life-threatening condition. Just as often, epidemiology and laboratory science converge to provide the evidence needed to establish causation. For example, epidemiologists were able to identify a variety of risk factors during an outbreak of pneumonia among persons attending the American Legion Convention in Philadelphia in 1976, even though the Legionnaires' bacillus was not identified in the laboratory from lung tissue of a person who had died from Legionnaires' disease until almost 6 months later. What use of epidemiology does this describe?
observational cohort
Occurrence of cancer was identified between April 1991 and July 2002 for 50,000 troops who served in the first Gulf War (ended April 1991) and 50,000 troops who served elsewhere during the same period. What type of analytical study is this?
Epidemics
Occurrences of diseases in which many people in the same place at the same time are affected
surveillance, field investigations, analytic studies
Often the methods are used in combination — with __________ and ________ ____________ providing clues or hypotheses about causes and modes of transmission, and ________ _______ evaluating the credibility of those hypotheses.
study, distribution, determinants, health-related states and events, specified populations, application
Overall, epidemiology is the _______ (scientific, systematic, data-driven) of the ____________ (frequency, pattern) and __________ (causes, risk factors) of _______-_________ ______ ____ _______ (not just diseases) in ________ _______ (patient is community, individuals viewed collectively), and the ________ of (since epidemiology is a discipline within public health) this study to the control of health problems.
observational case-control
Persons diagnosed with new-onset Lyme disease were asked how often they walk through woods, use insect repellant, wear short sleeves and pants, etc. Twice as many patients without Lyme disease from the same physician's practice were asked the same questions, and the responses in the two groups were compared. What type of analytical study is this?
assessing the community's health
Public health officials responsible for POLICY development, implementation, and evaluation use epidemiological information as a factual FRAMEWORK FOR DECISION MAKING. To assess the health of a population or community, relevant sources of data must be identified and analyzed by person, place, and time (descriptive epidemiology). - What are the actual and potential health problems in the community? - Where are they occurring? - Which populations are at increased risk? - Which problems have declined over time? - Which ones are increasing or have the potential to increase? - How do these patterns relate to the level and distribution of public health services available? More detailed data may need to be collected and analyzed to determine whether health services are available, accessible, effective, and efficient. For example, public health officials used epidemiological data and methods to identify baselines, to set HEALTH GOALS FOR THE NATION in 2000 and 2010, and to monitor progress toward these goals. What use of epidemiology does this describe?
application (Rifampin)
Recommend that close contacts of a child recently reported with meningococcal meningitis receive Rifampin. Would this describe distribution, determinants, or application?
observational cross-sectional
Representative sample of residents were telephoned and asked how much they exercise each week and whether they currently have (have ever been diagnosed with) heart disease. What type of analytical study is this?
field investigation (reviewing reports)
Reviewing reports of test results for Chlamydia trachomatis from public health clinics Would this match with public health surveillance, field investigation, analytic studies, evaluation, linkages, and policy development?
exposure, impact
Sometimes a graph shows the timing of events that are related to disease trends being displayed. For example, the graph may indicate the period of exposure or the date control measures were implemented. Studying a graph that notes the period of _________ may lead to insights into what may have caused illness. Studying a graph that notes the timing of control measures shows what _______, if any, the measures may have had on disease occurrence.
experimental
Subjects were children enrolled in a health maintenance organization. At 2 months, each child was randomly given one of two types of a new vaccine against rotavirus infection. Parents were called by a nurse two weeks later and asked whether the children had experienced any of a list of side-effects. What type of analytical study is this?
distribution (Cincinnati, Ohio)
Tabulate the frequency of clinical signs, symptoms, and laboratory findings among children with chickenpox in Cincinnati, Ohio. Would this describe distribution, determinants, or application?
health issue of concern
The 5W's of descriptive epidemiology: What =
time
The 5W's of descriptive epidemiology: When =
place (5Ws)
The 5W's of descriptive epidemiology: Where =
person
The 5W's of descriptive epidemiology: Who =
causes, risk factors, modes of transmission
The 5W's of descriptive epidemiology: Why/how =
descriptive epidemiology (the epidemiologist...)
The epidemiologist then performs _________ __________ by characterizing the cases collectively according to time, place, and person.
design, conduct, analysis, interpretation, and communication of findings
The hallmark of an analytic epidemiological study is the use of a valid comparison group. Epidemiologists must be skilled in all aspects of such studies, including the following.... (CADIC) or (DCAIC in order)
follow-up/prospective cohort studies
The length of follow-up varies considerably. In an attempt to respond quickly to a public health concern such as an outbreak, public health departments tend to conduct relatively brief studies. On the other hand, research and academic organizations are more likely to conduct studies of cancer, cardiovascular disease, and other chronic diseases which may last for years and even decades. The Framingham study is a well-known cohort study that has followed over 5,000 residents of Framingham, Massachusetts, since the early 1950s to establish the rates and risk factors for heart disease. The Nurses Health Study and the Nurses Health Study II are cohort studies established in 1976 and 1989, respectively, that have followed over 100,000 nurses each and have provided useful information on oral contraceptives, diet, and lifestyle risk factors. These studies are sometimes called ______-___ or _________ ______ _______, because participants are enrolled as the study begins and are then followed prospectively over time to identify occurrence of the outcomes of interest.
seasonally, sporadically
The occurrence of disease changes over TIME. Some of these changes occur regularly, while others are unpredictable. Two diseases that occur during the same season each year include influenza (winter) and West Nile virus infection (August-September). In contrast, diseases such as hepatitis B and salmonellosis can occur at any time. For diseases that occur ___________, health officials can anticipate their occurrence and implement control and prevention measures, such as an influenza vaccination campaign or mosquito spraying. For diseases that occur ___________, investigators can conduct studies to identify the causes and modes of spread, and then develop appropriately targeted actions to control or prevent further occurrence of the disease.
World War 2, Doll, Hill, smoking, cardiovascular, smallpox
The period since ________ _______ # has seen an explosion in the development of research methods and the theoretical underpinnings of epidemiology. Epidemiology has been applied to the entire range of health-related outcomes, behaviors, and even knowledge and attitudes. The studies by ____ and ____ linking lung cancer to _________ and the study of ______________ disease among residents of Framingham, Massachusetts are two examples of how pioneering researchers have applied epidemiological methods to chronic disease since World War II. During the 1960s and early 1970s health workers applied epidemiological methods to eradicate naturally occurring _________ worldwide. This was an achievement in applied epidemiology of unprecedented proportions.
collects information
Then, using this case definition, the epidemiologist finds and _________ __________ about the case-patients.
causes, effects, why, how, causal
Thus, analytic epidemiology is concerned with the search for ________ and ________, or the ____ and the ___. Epidemiologists use analytic epidemiology to quantify the association between exposures and outcomes and to test hypotheses about _______ relationships. It has been said that epidemiology by itself can never prove that a particular exposure caused a particular outcome. Often, however, epidemiology provides sufficient evidence to take appropriate control and prevention measures.
number or rate of cases, time periods, line graphs, histograms
Time data are usually displayed with a two-dimensional graph. The vertical or y-axis usually shows the ______ ___ _____ ___ ______; the horizontal or x-axis shows the _____ _______ such as years, months, or days. The number or rate of cases is plotted over time. Graphs of disease occurrence over time are usually plotted as ____ _____ or ________.
disease rate (to calculate..)
To calculate the _________ ______, the epidemiologist divides the number of cases by the size of the population.
How do epidemiologists search for determinants?
To search for these determinants, epidemiologists use ANALYTIC EPIDEMIOLOGY or EPIDEMIOLOGICAL STUDIES to provide the "WHY" and "HOW" of such events. They assess whether GROUPS with different rates of disease DIFFER IN their demographic characteristics, genetic or immunologic make-up, behaviors, environmental exposures, or other so-called potential RISK FACTORS. Ideally, the findings provide sufficient evidence to direct prompt and effective public health control and prevention measures.
epidemic period, incubation period, routes of transmission
To show the time course of a disease outbreak or epidemic, epidemiologists use this graph. As with the other graphs presented so far, this graph's y-axis shows the number of cases, while the x-axis shows time as either date of symptom onset or date of diagnosis. Depending on the _________ _______ (the length of time between exposure and onset of symptoms) and ______ __ _________, the scale on the x-axis can be as broad as weeks (for a very prolonged epidemic) or as narrow as minutes (e.g., for food poisoning by chemicals that cause symptoms within minutes). Conventionally, the data are displayed as a histogram (which is similar to a bar chart but has no gaps between adjacent columns). Sometimes each case is displayed as a square, as in Figure 1.10. The shape and other features of an epidemic curve can suggest hypotheses about the time and source of exposure, the mode of transmission, and the causative agent.
assessing the community's health, making decisions about individual patients, documenting the clinical picture of the illness, searching for causes to prevent future outbreaks
What are the four uses of epidemiology? (AMDS)
cohort studies and case-control studies
What are the two most common types of observational studies?
rate from specific population being studied is compared with the rate in an appropriate comparison group
What two groups does an epidemiologist compare to determine whether the disease rate is greater than what one would normally expect in an area?
eosinophilia, myalgias, eosinophilia-myalgia syndrome, SARS, non-acute, completing the clinical picture
When investigating a disease outbreak, epidemiologists rely on health-care providers and laboratorians to establish the proper diagnosis of individual patients. But epidemiologists also contribute to physicians' understanding of the clinical picture and natural history of disease. For example, in late 1989, a physician saw three patients with unexplained __________ (an increase in the number of a specific type of white blood cell called an eosinophil) and _______ (severe muscle pains). Although the physician could not make a definitive diagnosis, he notified public health authorities. Within weeks, epidemiologists had identified enough other cases to characterize the spectrum and COURSE OF THE ILLNESS that came to be known as __________-________ _________. More recently, epidemiologists, clinicians, and researchers around the world have collaborated to characterize ____, a disease caused by a new type of coronavirus that emerged in China in late 2002. Epidemiology has also been instrumental in characterizing many ___-______ diseases, such as the numerous conditions associated with cigarette smoking — from pulmonary and heart disease to lip, throat, and lung cancer. What use of epidemiology does this describe?
characteristic
When investigators find that persons with a particular ___________ are more likely than those without the characteristic to contract a disease, the characteristic is said to be associated with the disease. The characteristic may be a: - Demographic factor such as age, race, or sex; - Constitutional factor such as blood group or immune status; - Behavior or act such as smoking or having eaten salsa; or - Circumstance such as living near a toxic waste site. Identifying factors associated with disease help health officials appropriately target public health prevention and control activities. It also guides additional research into the causes of disease.
determinant (when you are comparing)
When you are COMPARING between two groups to find the cause of an issue, you are finding the __________
distribution (pattern in a specific area)
When you are looking at a pattern in a specific area, then you are observing the _________
individual, community
While a clinician is concerned about the health of an __________, the epidemiologist is concerned about the collective health of the people in a _____________
case definition, local, clinical criteria, outbreak investigations
a set of standard criteria for classifying whether a person has a particular disease, syndrome, or other health condition. Some of these, particularly those used for national surveillance, have been developed and adopted as national standards that ensure comparability. Use of an agreed-upon standard one of these ensures that every case is equivalent, regardless of when or where it occurred, or who identified it. To ensure that all health departments in the United States use the same case definitions for surveillance, the Council of State and Territorial Epidemiologists (CSTE), CDC, and other interested parties have adopted standard _______ __________ for the notifiable infectious diseases. These are revised as needed. In 1999, to address the need for common definitions and methods for state-level chronic disease surveillance, CSTE, the Association of State and Territorial Chronic Disease Program Directors, and CDC adopted standard definitions for 73 chronic disease indicators. Other ones, particularly those used in local outbreak investigations, are often tailored to the ______ situation. For example, a ______ ________ developed for an outbreak of viral illness might require laboratory confirmation where such laboratory services are available, but likely would not if such services were not readily available. - consists of _________ ________ and, sometimes, limitations on time, place, and person - when used during _________ __________, they are more likely to specify limits on time, place, and/or person than those used for surveillance
John Graunt
another early contributor to epidemiology who was a London haberdasher and councilman who published a landmark analysis of mortality data in 1662. This publication was the first to quantify patterns of birth, death, and disease occurrence, noting disparities between males and females, high infant mortality, urban/rural differences, and seasonal variations.
determinants
any factor, whether event, characteristic, or other definable entity, that brings about a change in a health condition or other defined characteristic epidemiologists search for this which are the causes and other factors that influence the occurrence of disease and other health-related events
# of cases/size of population
disease rate formula
John Snow
father of epidemiology in the mid 1800s, he was conducting a series of investigations in London that warrant his being considered the "father of field epidemiology." Twenty years before the development of the microscope, he conducted studies of CHOLERA outbreaks both to discover the CAUSE of disease and to PREVENT its recurrence
William Farr
father of modern vital statistics and surveillance He built upon Graunt's work by systematically collecting and analyzing BRITAIN'S MORTALITY STATISTICS. He is considered the father of MODERN VITAL STATISTICS and SURVEILLANCE, developed many of the basic practices used today in vital statistics and DISEASE CLASSIFICATION. He concentrated his efforts on collecting vital statistics, assembling and evaluating those data, and reporting to responsible health authorities and the general public.
On Airs, Waters, and Places, Hippocrates
in this essay __________ suggested that environmental and host factors such as behaviors might influence the development of disease
observational studies
in this study, the epidemiologist simply observes the exposure and disease status of each study participant. John Snow's studies of cholera in London were an example of this
experimental study
in this study, the investigator determines through a controlled process the exposure for each individual (clinical trial) or community (community trial), and then tracks the individuals or communities over time to detect the effects of the exposure. For example, in a clinical trial of a new vaccine, the investigator may randomly assign some of the participants to receive the new vaccine, while others receive a placebo shot. The investigator then tracks all participants, observes who gets the disease that the new vaccine is intended to prevent, and compares the two groups (new vaccine vs. placebo) to see whether the vaccine group has a lower rate of disease. Similarly, in a trial to prevent onset of diabetes among high-risk individuals, investigators randomly assigned enrollees to one of three groups — placebo, an anti-diabetes drug, or lifestyle intervention. At the end of the follow-up period, investigators found the lowest incidence of diabetes in the lifestyle intervention group, the next lowest in the anti-diabetic drug group, and the highest in the placebo group.
case-control study, control group, case, control
in this type of cohort study, investigators start by enrolling a group of people with disease (at CDC such persons are called case-patients rather than cases, because case refers to occurrence of disease, not a person). As a comparison group, the investigator then enrolls a group of people without disease (controls). Investigators then compare previous exposures between the two groups. The ________ _______ provides an estimate of the baseline or expected amount of exposure in that population. If the amount of exposure among the ______ group is substantially higher than the amount you would expect based on the ______ group, then illness is said to be associated with that exposure. The study of hepatitis A traced to green onions, described above, is an example of a this type of study. The key in this is to identify an appropriate control group, comparable to the case group in most respects, in order to provide a reasonable estimate of the baseline or expected exposure.
cross-sectional study
in this type of observational study, a sample of persons from a population is enrolled and their exposures and health outcomes are measured simultaneously. This type of study tends to assess the presence (prevalence) of the health outcome at that point of time without regard to duration. For example, in a study of diabetes, some of the enrollees with diabetes may have lived with their diabetes for many years, while others may have been recently diagnosed.
rates
measures that relate the numbers of cases during a certain period of time (usually per year) to the size of the population in which they occurred particularly useful for comparing the frequency of disease in different locations whose populations differ in size also useful for comparing disease occurrence during different periods of time
eccentricities
odd behavior; deviating from a conventional pattern
epi-
on/upon
analysis
one aspect of an analytic epidemiological study begins with describing the characteristics of the subjects. It progresses to calculation of rates, creation of comparative tables (e.g., two-by-two tables), and computation of measures of association (e.g., risk ratios or odds ratios), tests of significance (e.g., chi-square test), confidence intervals, and the like. Many epidemiological studies require more advanced analytic techniques such as stratified analysis, regression, and modeling. analyzing the data
design
one aspect of an analytic epidemiological study includes determining the appropriate research strategy and study design, writing justifications and protocols, calculating sample sizes, deciding on criteria for subject selection (e.g., developing case definitions), choosing an appropriate comparison group, and designing questionnaires. creating a plan
interpretation
one aspect of an analytic epidemiological study involves putting the study findings into perspective, identifying the key take-home messages, and making sound recommendations. Doing so requires that the epidemiologist be knowledgeable about the subject matter and the strengths and weaknesses of the study. making recommendations based on the data analyzed
conduct
one aspect of an analytic epidemiological study involves securing appropriate clearances and approvals, adhering to appropriate ethical principles, abstracting records, tracking down and interviewing subjects, collecting and handling specimens, and managing the data process of collecting data and investigating the case
field investigation, unreported, source
one of the major tasks of epidemiology in public health practice - One of the first actions that results from a surveillance case report or report of a cluster is investigation by the public health department. The investigation may be as limited as a phone call to the health-care provider to confirm or clarify the circumstances of the reported case, or it may involve a ________ ___________ requiring the coordinated efforts of dozens of people to characterize the extent of an epidemic and to identify its cause. - objectives of such investigations also vary. Investigations often lead to the identification of additional _________ or unrecognized ill persons who might otherwise continue to spread infection to others. For example, one of the hallmarks of investigations of persons with sexually transmitted disease is the identification of sexual partners or contacts of patients. When interviewed, many of these contacts are found to be infected without knowing it, and are given treatment they did not realize they needed. Identification and treatment of these contacts prevents further spread - For some diseases, investigations may identify a _______ or vehicle of infection that can be controlled or eliminated. For example, the investigation of a case of Escherichia coli O157:H7 infection usually focuses on trying to identify the vehicle, often ground beef but sometimes something more unusual such as fruit juice. By identifying the vehicle, investigators may be able to determine how many other persons might have already been exposed and how many continue to be at risk. When a commercial product turns out to be the culprit, public announcements and recalling the product may prevent many additional cases. - Occasionally, the objective of an investigation may simply be to LEARN MORE about the natural history, clinical spectrum, descriptive epidemiology, and risk factors of the disease BEFORE DETERMINING what disease intervention METHODS might be APPROPRIATE. Early investigations of the epidemic of SARS in 2003 were needed to establish a case definition based on the clinical presentation, and to characterize the populations at risk by time, place, and person. As more was learned about the epidemiology of the disease and communicability of the virus, appropriate recommendations regarding isolation and quarantine were issued.
policy development
one of the major tasks of epidemiology in public health practice - The definition of epidemiology ends with the following phrase: "...and the APPLICATION of this study to the control of health problems." - While some academically minded epidemiologists have stated that epidemiologists should stick to research and not get involved in policy development or even make recommendations, public health epidemiologists do not have this luxury - epidemiologists who understand a problem and the population in which it occurs are often in a uniquely qualified position to RECOMMEND appropriate INTERVENTIONS - As a result, epidemiologists working in public health regularly provide input, testimony, and recommendations regarding disease control strategies, reportable disease regulations, and health-care policy.
analytic studies
one of the major tasks of epidemiology in public health practice - employs rigorous methods needed to evaluate the CREDIBILITY OF HYPOTHESES - Clusters or outbreaks of disease frequently are investigated initially with descriptive epidemiology - Occasionally, when the association between exposure and disease is quite strong, the investigation may stop when descriptive epidemiology is complete and control measures may be implemented immediately. John Snow's 1854 investigation of cholera is an example. - More frequently, descriptive studies, like case investigations, generate hypotheses that can be tested with this. While some field investigations are conducted in response to acute health problems such as outbreaks, many others are planned studies
linkages, team sport, scales
one of the major tasks of epidemiology in public health practice - epidemiology is considered a "______ _______" - an epidemiologist usually participates as either a member or the leader of a MULTIDISCIPLINARY TEAM including laboratorians, infection control personnel, nurses, or other clinical staff, and, increasingly, computer information specialists - Many outbreaks cross geographical and jurisdictional lines, so co-investigators may be from local, state, or federal levels of government, academic institutions, clinical facilities, or the private sector (co-investigators from various ________) - To promote current and future collaboration, the epidemiologists need to maintain RELATIONSHIPS with staff of other agencies and institutions - mechanisms for sustaining this major task of epidemiology includes an official memoranda of understanding, sharing of published or on-line information for public health audiences and outside partners, and INFORMAL NETWORKING that takes place at professional meetings.
Public Health Surveillance, information for action, systems, patterns
one of the major tasks of epidemiology in public health practice - the ongoing, systematic collection, ANALYSIS, interpretation, and dissemination OF HEALTH DATA to help guide public health decision making and action - equivalent to monitoring the pulse of the community - sometimes called "________ ___ _______" - the purpose is to portray the ongoing patterns of disease occurrence and disease potential so that investigation, control, and prevention measures can be applied efficiently and effectively - This is accomplished through the systematic COLLECTION and evaluation of morbidity and mortality reports and other relevant HEALTH INFORMATION, and the dissemination of these data and their interpretation to those involved in disease control and public health decision making - relies on simple _________ to collect a limited amount of information about each case. Although not every case of disease is reported, health officials regularly review the case reports they do receive and look for ________ among them. These practices have proven invaluable in detecting problems, evaluating programs, and guiding public health action.
evaluation
one of the major tasks of epidemiology in public health practice - the process of determining, as systematically and objectively as possible, the relevance, effectiveness, efficiency, and impact of activities with respect to established goals - may focus on PLANS (formative evaluation), OPERATIONS (process evaluation), IMPACT (summative evaluation), or OUTCOMES — or any combination of these
sensitive case definition
one that is broad or "loose," in the hope of capturing most or all of the true cases For such rare but potentially severe communicable diseases, for which it is important to identify every possible case, health officials use this
demos
people
# of cases/size of population per unit of time
rate formula
frequency
refers not only to the number of health events such as the number of cases of meningitis or diabetes in a population, but also to the relationship of that number to the size of the population. The resulting rate allows epidemiologists to compare disease occurrence across different populations. the relationship of the # of cases with the population of a specified area so that epidemiologists can compare the disease occurrence across different populations
effectiveness
refers to the ability of a program to produce the intended or expected results in the field
efficiency
refers to the ability of the program to produce the intended results with a minimum expenditure of time and resources
pattern, time, place, person
refers to the occurrence of health-related events by _______, _______, and _________. Time patterns may be annual, seasonal, weekly, daily, hourly, weekday versus weekend, or any other breakdown of time that may influence disease or injury occurrence. Place patterns include geographic variation, urban/rural differences, and location of work sites or schools. Personal characteristics include demographic factors which may be related to risk of illness, injury, or disability such as age, sex, marital status, and socioeconomic status, as well as behaviors and environmental exposures.
disadvantages
requirement that everyone with symptoms be tested and an underestimation of the total number of cases if some people with salmonellosis are not tested are ___________ of using a strict case definition
cohort study, comparison group
similar in concept to the experimental study. In this study, the epidemiologist records whether each study participant is exposed or not, and then tracks the participants to see if they develop the disease of interest. Note that this differs from an experimental study because, in this study, the investigator observes rather than determines the participants' exposure status. After a period of time, the investigator compares the disease rate in the exposed group with the disease rate in the unexposed group. The unexposed group serves as the _________ ______, providing an estimate of the baseline or expected amount of disease occurrence in the community. If the disease rate is substantively different in the exposed group compared to the unexposed group, the exposure is said to be associated with illness.
Epidemiology
the STUDY of the DISTRIBUTION and DETERMINANTS of HEALTH-RELATED STATES OR EVENTS in SPECIFIED POPULATIONS, and the APPLICATION of this study to the control of health problems Branch of medical science concerned with the incidence, distribution, and control of diseases that affect large numbers of people.
efficacy
the ability to produce results under ideal conditions
Morbidity Report
the form used to report most diseases and other conditions to the Public Health Department
logos
the study of
surveillance and field investigations
these are usually sufficient to identify causes, modes of transmission, and appropriate control and prevention measures.
place patterns
these types of patterns include geographic variation, urban/rural differences, and location of work sites or schools
person patterns
these types of patterns include personal characteristics such as demographic factors which may be related to risk of illness, injury, or disability like age, sex, marital status, and socioeconomic status, as well as behaviors and environmental exposure
time patterns
these types of patterns may be annual, seasonal, weekly, daily, hourly, weekday versus weekend, or any other breakdown of time that may influence disease or injury occurrence
clinical criteria
usually include confirmatory laboratory tests, if available, or combinations of symptoms (subjective complaints), signs (objective physical findings), and other findings
1854
when did John Snow conduct a series of investigations in London that warrant his being considered the "father of field epidemiology." Twenty years before the development of the microscope, he conducted studies of CHOLERA outbreaks both to discover the CAUSE of disease and to PREVENT its recurrence