Chapter 7 And 8 Study Guide Flashcards
What is an epidemic?
Refers to a disease occurrence that clearly exceeds the normal or expected frequency in a community or region
What is an example of an epidemic?
Opioid epidemic
What is a pandemic?
Is worldwide in distribution
What are examples of a pandemic?
-COVID 19
-HIV/AIDS
What is a hyperendemic?
Refer to a disease which is constantly and persistently present in a population at a high rate of incidence and/or prevalence and which equally affects all age groups of that population
What are examples of a hyperendemic?
-Dengue fever
-Malaria
What is an endemic?
When a disease or infectious agent is continually found in a particular area or population
What is the epidemiologic triangle or host, agent, and environment model?
-Host
1. Demographics
2. Immunity
3. Disease history
4. Lifestyle factors
-Environment
1. Pollution
2. Built environment
3. Psychosocial environment
4. Climate
-Agent
1. Bacteria/viruses
2. Chemical (drugs)
3. Trauma
4. Food/water
5. Stress
What is a host?
-A susceptible human or animal who harbors and nourishes a disease-causing agent
-Many physical, psychological, and lifestyle factors influence the host’s susceptibility and response to an agent
1. Physical factors: age, sex, race, socioeconomic status, and genetic influences
2. Psychological factors: outlook and response to stress
3. Lifestyle factors: diet, exercise, and other healthy or unhealthy habits
-Resistance can be promoted through preventive interventions that improve one’s immunity system and support a healthy lifestyle
1. Such healthy habits include not smoking, eating more fruits and vegetables, exercising regularly, maintaining a healthy weight, drinking alcohol in moderation, getting adequate sleep, washing hands frequently, cooking meals thoroughly, and minimizing stress
What is an agent?
-A factor that causes or contributes to a health problem or condition
-Causative agents can be factors that are present (e.g., bacteria that cause TB, rocks on a mountain road that contribute to an automobile crash) or factors that are lacking (e.g., a low serum iron level that causes anemia or the lack of seat belt use contributing to the extent of injury in an automobile crash)
-Agents vary considerably and include five types: biologic, chemical, nutrient, physical, and psychological
-Agents may also be classified as infectious or noninfectious
1. Infectious agents cause communicable diseases, such as influenza or TB—that is, the disease can be spread from one person to another
What are biologic agents?
-Include bacteria, viruses, fungi, protozoa, worms, and insects
-Some biologic agents are infectious, such as influenza virus or HIV
What are chemical agents?
-May be in the form of liquids, solids, gases, dusts, or fumes
-Examples are poisonous sprays used on garden pests and industrial chemical wastes
-The degree of toxicity of the chemical agent influences its impact on health
What are nutrient agents?
-Include essential dietary components that can produce illness conditions if they are deficient or are taken in excess
-For example, a deficiency of niacin can cause pellagra, and too much vitamin A can be toxic
What are physical agents?
-Include anything mechanical (e.g., chainsaw, automobile), material (e.g., rockslide), atmospheric (e.g., ultraviolet radiation), geologic (e.g., earthquake), or genetically transmitted that causes injury to humans
-The shape, size, and force of physical agents influence the degree of harm to the host
What are psychological agents?
Events that produce stress leading to health problems (e.g., war, terrorism)
What certain characteristics of infectious agents are important for C/PHNs to understand?
-Exposure to the agent
-Pathogenicity (capacity to cause disease in the host)
-Infectivity (capacity to enter the host and multiply)
-Virulence (severity of disease)
-Toxigenicity (capacity to produce a toxin or poison)
-Resistance (ability of the agent to survive environmental conditions)
-Antigenicity (ability to induce an antibody response in the host)
-Structure and chemical composition
What is environment?
-Refers to all the external factors surrounding the host that might influence vulnerability o resistance and includes physical and psychosocial elements
-The physical environment includes factors such as geography, climate and weather, safety of buildings, water and food supply, and presence of animals, plants, insects, and microorganisms that have the capacity to serve as reservoirs (storage sites for disease-causing agents) or vectors (carriers) for transmitting disease
-The psychosocial environment refers to social, cultural, economic, and psychological influences and conditions that affect health, such as access to health care, cultural health practices, poverty, and work stressors, which can all contribute to disease or health
What is inherent resistance?
-People sometimes have an ability to resist pathogens
-Typically, these people have inherited or acquired characteristics, such as the various factors mentioned earlier, that make them less vulnerable
1. For instance, people who maintain a healthful lifestyle may not contract influenza even if exposed to the flu virus
What is host?
Human becomes infected with an agent
What is a reservoir?
-I.e., where the causal agent can live and multiply
-With plague, that reservoir may be other humans, rats, squirrels, and a few other animals
-With malaria, infected humans are the major reservoir for the parasitic agents, although certain nonhuman primates also act as reservoirs
What is a portal of entry?
-Any route that a pathogen uses to enter the body (host)
-In the case of malaria, the mosquito bite provides a portal of exit as well as a portal of entry into the human host
What are the basic principles of immunity?
-Immunity
-Active immunity
-Passive immunity
-Cross immunity
-Antigen
-Antibody
What is immunity?
-Refers to a host’s ability to resist a particular infectious disease-causing agent
-This occurs when the body forms antibodies and lymphocytes that react with the foreign antigenic molecules and render them harmless
-Self versus nonself
-Protection from infectious disease
-Usually indicated by the presence of antibody
-Generally specific to a single organism
What is active immunity?
-Long-term (sometimes lifelong) resistance to a specific disease-causing organism; it also can be acquired naturally or artificially
-Naturally acquired active immunity occurs when a person contracts a disease, whereas artificial immunity occurs when a person receives an inoculation of an antigen through a vaccine
-Protection produced by the person’s own immune system
-Often lifetime
What is passive immunity?
-Short-term resistance to a specific disease-causing organism; it may be acquired naturally (as with newborns through maternal antibody transfer) or artificially through inoculation with pooled human antibody (e.g., immunoglobulin) that gives temporary protection
-Protection transferred from another animal or human
-Effective protection that wanes with time
What is cross immunity?
-Immunity to one bacteria or virus is effective in protecting the person against an antigenically similar but different organism
-Ex: cowpox vaccination protects against smallpox
What is an antigen?
A live (e.g., viruses and bacteria) or inactivated substance capable of producing an immune response
What is an antibody?
Protein molecules (immunoglobulins) produced by B lymphocytes to help eliminate an antigen
What is herd immunity?
-Or community immunity describes the immunity level that is present in a population group
-A population with low herd immunityh is one with few immune members; consequently, it is more susceptible to a particular disease
-Nonimmune people are more likely to contract the disease and spread it throughout the group, placing the entire population at greater risk
-Conversely, a population with high herd immunity is one in which the immune people in the group outnumber the susceptible people; consequently, the incidence of a particular disease is reduced
1. The level of herd immunity may vary with diseases
-Mandatory preschool immunizations and required travel vaccinations are applications of the herd immunity concept
What is risk in epidemiology?
-A population at risk is a collection of people among whom a health problem has the possibility of developing because certain influencing factors are present (e.g., exposure to HIV) or absent (e.g., lack of childhood immunizations, lack of specific vitamins in the diet), or because there are modifiable risk factors present (e.g., cardiovascular disease)
-Epidemiologists measure this difference using the relative risk ratio, which statistically compares the disease occurrence in the population at risk with the occurrence of the same disease in people without that risk factor
-If the risk of acquiring the disease is the same regardless of exposure to the risk factor studied, the ratio will be 1:1, and the relative risk will be 1.0
-A relative risk >1.0 indicates that those with the risk factor have a greater likelihood of acquiring the disease than do those without it; for instance, a relative risk of 2.54 means that the exposed group is 2.54 times more likely to acquire the disease than the unexposed group
What determines a risk?
-The probability that a disease or other unfavorable health condition will develop
-For any given group of people, the risk of developing a health problem is directly influenced, either positively or negatively, by such factors as their biology or inherited health capacity, living environment, lifestyle choices, and system of health care
-When such factors are negative influences, they are called risk factors
-The degree of risk is directly linked to susceptibility or vulnerability to a given health problem
What is the natural history of a disease or health condition?
-Any disease or health condition follows a progression known as its natural history, which refers to events that occur before its development, during its course, and during its conclusion
-This process involves the interactions among a susceptible host, the causative agent, and the environment
-The natural progression of a disease occurs in four stages in terms of how it affects a population: (1) susceptibility, (2) preclinical (subclinical) disease, (3) clinical disease, and (4) resolution
-The last stage, resolution, includes recovery, disability, or death
-The stages may be grouped into two phases: phase I (prepathogenesis), which includes stages 1 and 2, and phase II (pathogenesis), which includes stages 3 and 4
-C/PHNs can intervene at any point during these four stages to delay, arrest, or prevent the progression of the disease or condition
-Primary, secondary, and tertiary prevention can be applied to each of the stages
1. However, primary prevention through health promotion and education strategies and health protection policies is the best and most cost-effective approach to ensuring population health
What is the susceptibility stage?
-The disease is not present, and individuals have not been exposed, but host and environmental factors influence their susceptibility
-If a pathogen invades and the immune system’s response is effective, then the infection is eliminated or contained and the disease does not occur
What is the subclinical disease stage?
-Individuals have been exposed to a disease but are asymptomatic
-In infectious diseases, it includes an incubation period of hours to months (or years, in the case of AIDS), during which the organism multiplies to sufficient numbers to produce a host reaction and clinical symptoms
-In noninfectious disease, it includes an induction or latency period, which is the time from exposure to the onset of symptoms and is often years to decades (e.g., up to 40 years from exposure to asbestos and development of lung cancer)
What is the clinical disease stage?
-Signs and symptoms of the disease or condition develop, and diagnosis may occur
-Early signs may be evident only through laboratory test findings (e.g., premalignant cervical changes evident on Papanicolaou smears), whereas later signs are more likely to be acute and clearly visible (e.g., enterocolitis in a salmonellosis outbreak)
What is the resolution or advanced disease stage?
Depending on its severity, the disease may conclude with a return to health, a residual or chronic form of the disease with some disabling limitations, or death
What is incidence?
-Not everyone in a population is at risk for developing a disease, incurring an injury, or having some other health-related characteristic
-1. The incidence rate recognizes this fact
-Incidence refers to all new cases of a disease or health condition appearing during a given time
-Incidence rate describes a proportion in which the numerator is all new cases appearing during a given period of time and the denominator is the population at risk during the same period
What is attack rate?
-Another rate that describes incidence is the attack rate
-An attack rate describes the proportion of a group or population that develops a disease among all those exposed to a particular risk
-This term is used frequently in investigations of outbreaks of infectious diseases such as influenza
-If the attack rate changes, it may suggest an alteration in the population’s immune status or that the disease-causing organism is present in a more or less virulent strain
What is prevalence?
-Refers to all of the people with a particular health condition existing in a given population at a given point in time
-The prevalence rate describes a situation at a specific point in time
-If a nurse discovers 50 cases of measles in an elementary school, that is a simple count
-When this number is divided by the total number of students in the school, the result is the prevalence of measles
1. For instance, if the school has 500 students, the prevalence of measles on that day would be 10% (50 measles/500 population)
-The prevalence rate over a defined period of time is called a period prevalence rate
What are the methods in the epidemiologic investigative process?
-Descriptive
-Analytic
-Experimental
What is descriptive epidemiology?
-Includes investigations that seek to observe and describe patterns of health-related conditions that occur naturally in a population
-At this stage in the epidemiologic investigation, the researcher seeks to establish the occurrence of a problem
-Data from descriptive studies suggest hypotheses for further testing
-Descriptive studies almost always involve some form of broad-based quantification and statistical analysis
-Descriptive studies can be retrospective (identify cases and controls, then go back to review existing data) or prospective (identify groups and exposure factors, and then follow them forward in time)
-Includes counts, rates, computing rates
