Disease Quiz
Pathogen
Biological hazards from more than 1,400 pathogens that can infect humans. A pathogen is a living organism that can cause disease in another organism. Examples are bacteria, viruses, parasites, protozoa, and fungi.
Pandemic
A global epidemic, such as AIDS is called a pandemic.
Epidemic
A large-scale outbreak of an infectious disease in an area or country is called an epidemic.
Know whether it is caused by a bacteria, virus, or protozoa and what effects it has on the body: Tuberculosis
-Bacteria -Many infected do not appear to be sick, and about half of them do not know they are infected; can sometimes have a chronic cough
Know whether it is caused by a bacteria, virus, or protozoa and what effects it has on the body: Malaria
-Protozoa -It infects and destroys red blood cells, causing intense fever, chills, drenching sweats, anemia, severe abdominal pain, headaches, vomiting, extreme weakness, greater susceptibility to other diseases, and is deadly
Know whether it is caused by a bacteria, virus, or protozoa and what effects it has on the body: Ebola
-Virus -Attacks the immune system's cells and nuetralizes its responses - allowing the virus to proliferate. Causes high temperature, aching, and sore throat which progress into vomiting, rashes, and diarrhea
Know whether it is caused by a bacteria, virus, or protozoa and what effects it has on the body: SARS
-Virus -Causes flu-like symptoms, can quickly turn into life-threatening pneumonia, and is deadly
Know whether it is caused by a bacteria, virus, or protozoa and what effects it has on the body: Hepititis B
-Virus -Damages the liver and is deadly
Know whether it is caused by a bacteria, virus, or protozoa and what effects it has on the body: HIV/AIDS
-Virus -Effects the immune system and leaves the body vulnerable to infections such as tuberculosis (TB) and rare forms of cancer such as Kaposi's Sarcoma
Know whether it is caused by a bacteria, virus, or protozoa and what effects it has on the body: Influenza
-Virus -High fever, cough and muscle aches, usually come on suddenly and are more severe than colds
Know whether it is caused by a bacteria, virus, or protozoa and what effects it has on the body: West Nile Virus
-Virus (from mosquitos) -Causes severe illness including encephalitis and meningitis and is deadly
Nontransmissible disease
A nontransmissible disease is caused by something other than a living organism and does not spread from one person to another. Such diseases tend to develop slowly and have multiple causes. Examples include cardiovascular (heart and blood vessel) diseases, most cancers, asthma, diabetes, and malnutrition. As average life expectancy increases, people are more likely to suffer and die from nontransmissible diseases such as cardiovascular diseases and cancers.
Transmissible disease
A transmissible disease (also called a contagious or communicable disease) is an infectious disease that can be transmitted from one person to another. Examples are flu, HIV, tuberculosis, and measles.
What area of the world is most affected by HIV/ AIDS? What are the consequences to the populations of these countries?
AIDS has reduced the life expectancy of the 750 million people living in sub-Saharan Africa from 62 to 47 years—40 years in the seven countries most severely affected by AIDS. The premature deaths of teachers, health-care workers, soldiers, and other young productive adults in such countries leads to diminished education and health care, decreased food production and economic development, and disintegrating families. This means that countries like Botswana are expected to lose half of their adult populations within a decade. Such death rates drastically alter a country's age structure. AIDS has also left more than 15 million children orphaned—roughly equal to the number of children under age 5 in the United States. Many of these orphans are forced into child labor or the sex trade.
Be able to list some ways (at least 4) that we can reduce the incidence of infectious diseases.
According to the WHO, the global death rate from infectious diseases decreased by about two-thirds between 1970 and 2000 and is projected to continue dropping. Also, between 1971 and 2000, the percentage of children in developing countries immunized with vaccines to prevent tetanus, measles, diphtheria, typhoid fever, and polio increased from 10% to 84%— saving about 10 million lives each year. It costs about $30 to get a basic package of vaccines to a child—an affordable way to save a child's life for roughly the price of a single night out at the movies in a developed country. Figure 17-10 lists measures promoted by health scientists and public health officials to help prevent or reduce the incidence of infectious diseases—especially in developing countries. An important breakthrough has been the development of simple oral rehydration therapy to help prevent death from dehydration for victims of severe diarrhea, which causes about one-fourth of all deaths of children younger than age 5. It involves administering a simple solution of boiled water, salt, and sugar or rice, at a cost of only a few cents per person. It has been the major factor in reducing the annual number of deaths from diarrhea from 4.6 million in 1980 to 1.9 million in 2006. Few investments have saved so many lives at such a low cost. In 2006, the WHO estimated that implementing the solutions in Figure 17-10 could save the lives of as many as 4 million children younger than age 5 each year. Recall that more than a third of the world's people—2.6 billion—do not have decent bathroom facilities, and more than a billion get their water for drinking, washing, and cooking from sources polluted by animal and human feces. A key to reducing sickness and premature death from infectious disease is to focus on providing people with simple latrines and access to safe drinking water. The U.N. estimates that this could be done for about $20 billion a year—about what rich countries with almost universal access to clean water spend each year on bottled water. Bad news. The WHO estimates that only 10% of global medical research and development money goes toward preventing infectious diseases in developing countries, even though more people worldwide suffer and die from these diseases than from all other diseases combined. Fortunately, the problem is getting more attention. In recent years, philanthropists including Bill and Melinda Gates and Warren E. Buffet have donated billions of dollars to improve global health, with primary emphasis on preventing infectious diseases in developing countries.
Infectious disease
An infectious disease is caused when a pathogen such as a bacterium, virus, or parasite invades the body and multiplies in its cells and tissues - causes disease. Examples are flu, HIV, malaria, tuberculosis, and measles.
What are zoonotic diseases? Why has the incidence of these diseases increased in the last half century?
Diseases passed on from animals to humans. West Nile and SARS are examples of diseases that move from animals to humans. Zoonotic diseases have increased as more people move into undeveloped areas to settle and interact with wildlife species, buying and selling wild animals internationally, raising livestock on factory farms, consuming bush meat, and clearing forest.
Why has the leading cause of death in most countries shifted from transmissible to nontransmissible diseases since 1900?
In 1900, infectious disease was the leading cause of death in the world and in the United States. Since then, and especially since 1950, the incidences of infectious diseases and the death rates from such diseases have been greatly reduced. This has been achieved mostly by a combination of better health care, the use of antibiotics to treat infectious diseases caused by bacteria, and the development of vaccines to prevent the spread of some infectious viral diseases. As a result, average life expectancy has increased in most countries, the leading cause of death has shifted to nontransmissible cardiovascular disease, and the percentage of people dying from cancers is increasing in both developed and developing countries.
Know why genetic resistance to antibiotics is becoming more common and how this relates to MRSA
We risk falling behind in our efforts to prevent infectious bacterial diseases because of the astounding reproductive rate of bacteria, some of which can produce well over 16 million offspring in 24 hours. This allows bacteria to become genetically resistant to an increasing number of antibiotics through natural selection. In addition, some drug-resistant bacteria can quickly transfer their resistance to nonresistant bacteria by exchanging genetic material. Other factors play a key role in fostering such genetic resistance. One is the spread of bacteria (some beneficial and some harmful) around the globe by human travel and international trade. Another is the overuse of pesticides, which increases populations of pesticide-resistant insects and other carriers of bacterial diseases. Yet another factor is overuse of antibiotics. According to a 2000 study by Richard Wenzel and Michael Edward, at least half of all antibiotics used to treat humans are prescribed unnecessarily. In many countries, antibiotics are available without a prescription, which promotes unnecessary use. Resistance to some antibiotics has increased because of their widespread use in livestock and dairy animals to control disease and to promote growth. Also, the growing use of antibacterial hand soaps and other cleansers is probably promoting genetic resistance. As a result of these factors acting together, every major disease-causing bacterium now has strains that resist at least one of the roughly 160 antibiotics used to treat bacterial infections such as tuberculosis. Each year, genetic resistance to antibiotics plays a role in the deaths of at least 90,000 of the 2 million people who pick up mostly preventable infections while they are in U.S. hospitals, according to the U.S. Centers for Disease Control and Prevention. This serious problem is much worse in hospitals in many other countries. A bacterium known as methicillin-resistant staphylococcus aureus, or MRSA, has become resistant to most common antibiotics. This staph infection first appears on the skin as a red, swollen pimple or boil that may be painful and have pus. Many victims think they have a spider bite that will not heal. MRSA can cause a vicious type of pneumonia, flesheating wounds, and a quick death if it gets into the bloodstream. This staph germ typically thrives on the body (mostly on the skin and in the nose) in health care settings where people have open wounds and tubes. But in recent years, it has been increasingly found in the general population. It can be picked up on playgrounds, in meeting rooms, and in gyms. It can spread through skin contact, tattoo needles, and contact with poorly laundered clothing items or shared items such as towels. In 2005, MRSA infections contributed to the premature deaths of 18,650 people in the United States (more than the 17,000 who died from AIDS). Ways to reduce the chances of infection from MRSA include frequent, thorough washing of hands; careful cleansing of even superficial wounds with soap and water; covering all wounds with a clean, dry bandage; and not sharing towels or other linens. Most antibiotics work by crippling key proteins inside bacteria. But bacteria often develop immunity to such chemicals by modifying their protein receptor sites in ways that prevent the antibiotic molecules from entering their cells. In 2008, University of Pennsylvania scientists developed a compound that mimics molecules they identified in frog skin that essentially stab staph bacteria to death. This has inspired a new approach toward killing harmful bacteria by poking thousands of tiny holes in the bacterium's membranes. Ironically, at a time when chemical knowledge gained by studying amphibians could save millions of human lives, our activities are threatening many of the world's amphibian species..
How is malaria transmitted? Where in the world is it prevalent? How could climate change affect the number of cases of malaria worldwide?
Malaria is caused by a parasite that is spread by the bites of certain mosquito species. Four species of protozoan parasites in the genus Plasmodium cause malaria. Most infections occur when an uninfected female of any of about 60 Anopheles mosquito species bites a person (usually at night) who is infected with Plasmodium parasite, ingests blood that contains the parasite, and later bites an uninfected person. Plasmodium parasites then move out of the mosquito and into the human's bloodstream and liver where they multiply. Malaria can also be transmitted by blood transfusions and by drug users sharing needles. The malaria cycle repeats itself until immunity develops, treatment is given, or the victim dies. Over the course of human history, malarial protozoa probably have killed more people than all the wars ever fought. During the 1950s and 1960s, the spread of malaria was sharply curtailed when swamplands and marshes where mosquitoes were breeding were drained or sprayed with insecticides, and drugs were used to kill the parasites in victims' bloodstreams. Since 1970, however, malaria has come roaring back. Most species of the Anopheles mosquito have become genetically resistant to most insecticides. Worse, the Plasmodium parasites have become genetically resistant to common antimalarial drugs. In addition, clearing and developing tropical forests leads to the spread of malaria among workers and the settlers who follow. Global warming is also likely to increase cases of malaria as populations of malaria-carrying mosquitoes spread to warmer areas. Prevalent in sub-Sahara Africa.
Know the top three diseases that kill the most people each year
Pneumonia and flu, HIV/AIDS, and diarrheal diseases
Why has the incidence of TB increased in recent years?
Several factors account for the recent increase in TB incidence. One is that there are too few TB screening and control programs, especially in developing countries, where 95% of the new cases occur. A second problem is that most strains of the TB bacterium have developed genetic resistance to the majority of the effective antibiotics. Also, population growth, urbanization, and air travel have greatly increased person-to-person contacts, and TB has spread, especially in areas where large numbers of poor people crowd together. In addition, AIDS greatly weakens its victims' immune systems, which allows TB bacteria to multiply in AIDS victims.
How is HIV transmitted from person to person? What are some strategies that are suggested to slow the spread of AIDS?
The virus is transmitted from one person to another by unsafe sex, sharing of needles by drug users, infected mothers who pass the virus on to their offspring before or during birth, and exposure to infected blood. According to the WHO, a global strategy to slow the spread of AIDS should have six major priorities. First, reduce the number of new infections below the number of deaths. Second, concentrate on the groups in a society that are most likely to spread the disease, such as sex workers, intravenous drug users, and soldiers. Third, provide free HIV testing and pressure people from high-risk groups to get tested. Fourth, implement a mass-advertising and education program geared toward adults and schoolchildren to help prevent the disease, and emphasize abstinence, condom use, and male circumcision (which apparently can reduce the transmission of HIV to men from infected female partners by up to 60%). Fifth, provide free or low-cost drugs to slow the progress of the disease. Sixth, increase funding for research on the development of microbiocides such as a vaginal gel that could help women to protect themselves from getting HIV/AIDS.
How is Ebola transmitted from person to person? How is Ebola connected to the consumption of bushmeat?
Transmitted through bodily fluids from an infected person to a non-infected person through passage ways. Not contagious until having symptoms. Butchering and eating some forms of bush meat has helped to spread fatal diseases such as HIV/AIDS and the Ebola virus to humans.