Epidemiology HOSA – Flashcards
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epidemiology
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scientific method used to investigate, analyze and prevent or control a health problem in a population.
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Epidemic
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a health problem that exists in a community to a greater degree than you would expect.
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Bias
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a flaw in either the study design or data analysis that leads to an erroneous result.
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Case Fatality rate
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mathematical quantity that describes the severity of a disease Y, proportion of persons diagnosed with a disease Y who actually die from disease Y during the period of observation:
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exposure
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generic term used to describe the effective presence of any agent or factor that is thought to cause disease
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Hypothesis testing
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The epidemiological process by which researchers ask the question: " Does the association that I have observed represent a causal relationship between the putative exposure and the disease?"
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Prevalence
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mathematical quantity that describes the presence of a disease Y in a population # with disease Y in population p at a given time # in population p
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Incidence
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the occurrence of a disease Y in a population. It is the proportion of persons in the population who newly develop the disease Y within a given time period (t) # who develop the disease Y in population p in a time t # in population p
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Racial and ethnic health disparities
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There are very few diseases for which those differences result from biological factors others can usually be traced to socioeconomic phenomena
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Attributable risks
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group of measures which describe the amount of disease risk that can be attributed to a given factor X (Incidence in population) - (Incidence in unexposed group)]/ (Incidence in population)
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Screening
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process of early diagnosis of a disease, i.e. identification of disease or risk factors for the disease in its pre-symptomatic or pre-clinical stage. Breast cancer screening
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Passive Surveillance
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more common form of surveillance used by most local and state health departments; health care providers report notifiable conditions
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active surveillance
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data actively collected, more specific objective, information-gathering tools (questionnaires etc), more useful in epidemiological research than passive.
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Dallas Fire Study
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Study measured fires in dallas neighborhoods to find causation, concluded that control efforts to prevent house fire injuries should target the elderly, minorities, low-income populations and houses without functioning smoke alarms.
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cohort study
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A type of epidemiologic study where a group of exposed individuals (individuals who have been exposed to the potential risk factor) and a group of non-exposed individuals are followed over time to determine the incidence of disease. Follow up studies with people without disease but with exposure
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case control study
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A study type that uses cases (with the health problem) and compares them with controls (without the health problem) to find out what may have caused the problem. A type of retrospective study.
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cross sectional study
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A research study that examines the effects of development (maturation) by examining different subjects at various ages
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ecologic study
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Epidemiologic study in which the units of analysis are populations or groups of people rather than individuals. Large groups studied like carrolton community
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descriptive epidemiology
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The aspect of epidemiology concerned with organizing and summarizing health-related data according to time, place, and person
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analytic epidemiology
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a form of epidemiology that investigates causes and associations between factors or events and health
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contingency table
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Shows risk factor by creating a 2x2 table marked with disease and exposure.
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Relative risk
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The ratio of the incidence of the condition in people who have the risk factor to the incidence of the condition in people who do not have it.
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Risk difference
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Risk exposed-risk unexposed
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attributable fraction
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proportion of disease Y in population that can be attributed to factor X
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Criteria for causal relationships
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exposure occurring before the outcome; the strength of the association; the existence of an incremental increase in risk associated with increase in degree of exposure to the risk factor; consistency of the association across various studies; and biological plausibility of the proposed causal link between exposure and outcome.
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sensitivity
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the proportion of people with the condition who have a positive test result.
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specificity
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the proportion of people without the condition who have a negative test result
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Predictive value of positive
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Proportion of those with a positive test who have the disease
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predictive value of negative
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Proportion of those with a negative test who do not have the disease
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Epidemiological ethics
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Informed consent, keeping confidentiality/privacy, explaining experiment/study, debriefing,
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infectious disease
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a disease that is caused by the invasion of a host by agents whose activities harm the host's tissues and can be transmitted to other individuals
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pathogens
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Microorganisms that are capable of causing disease, enter through natural orifices
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infection
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when a pathogen invades and begins growing within a host.
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Microbes That Cause Infectious Diseases
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Bacteria, viruses, fungi, protozoa, hemlithins, prions.
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Disease reservoirs
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Is the site where the infectious agent survives
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Modes of transmission
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Direct: Direct contact occurs when an individual is infected by contact with the reservoir, ex: touching infected person Indirect: when a pathogen can withstand the environment outside its host for a long period of time before infecting another individual. Ex: eating contaminated food
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Nonspecific mechanisms
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Protect against a wide range of pathogen, main source of protection.These mechanisms include anatomical barriers to invading pathogens, physiological deterrents to pathogens, and the presence of normal flora. Ex: Nasal opening
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Specific mechanisms of host resistance
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This specific immune response enables the body to target particular pathogens and pathogen-infected cells for destruction. Ex: B and T cells
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Immunity
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Because memory cells are present, this response happens much more quickly than in the initial encounter with the antigen.
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vaccine
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Either a killed or weakened (attenuated) strain of a particular pathogen, or a solution containing critical antigens from the pathogen. Exposure builds immunity. Smallpox eradicated due to vaccination
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Public Health Measures to Prevent Infectious Diseases
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Safe water, waste disposal, food safety, animal control, vaccination, and public health awareness organizations
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Treatment of bacterial diseases
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develop antibacterial drugs that have minimal side effect, these inhibit cell wall synthesis, protein synthesis, nucleic acid synthesis, or other enzyme-catalyzed reactions.
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Treatment of viral diseases
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drugs that effectively inhibit viral infections are highly toxic to host cells because viruses use the host's metabolic enzymes in their reproduction. For this reason, most illnesses due to viruses are treated symptomatically until the host's immune system controls and eliminates the pathogen (or the host dies)
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Emerging infectious diseases
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diseases that (1) have not occurred in humans before (this type of emergence is difficult to establish and is probably rare); (2) have occurred previously but affected only small numbers of people in isolated places (AIDS and Ebola hemorrhagic fever are examples); or (3) have occurred throughout human history but have only recently been recognized as distinct diseases due to an infectious agent (Lyme disease and gastric ulcers are examples).
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Re-emerging infectious diseases
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Diseases that once were major health problems globally or in a particular country, and then declined dramatically, but are again becoming health problems for a significant proportion of the population (malaria and tuberculosis are examples).
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Portal of exit
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Path by which pathogen leaves host
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Portal of entry
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Path by which pathogen enters host, transmissions
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Host suceptibility
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specific immunity, genetics, antibodies, lifestyle
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Herd immunity
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You'll be immune if most others around you are immune
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endemic
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Amount of disease that is usually in a community, usually constant small force
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Hyperendemic
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Persistent, high levels of disease
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Outbreak
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Increase in number of people with disease in a particular area
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cluster
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cases grouped along similar place and time
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pandemic
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epidemic that has spread over any continents and affects a large number of people. Plague
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Common source outbreak
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All persons are exposed from same source. McDonalds near CVS sells infected poop in chicken.
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Propagated outbreak
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An outbreak that does not have a common source and spreads gradually from person to person over more than one incubation period
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point source outbreak
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All individuals affected are exposed at or around the same time. Cases occur after a MINIMUM and within 1 incubation time. This outbreak stops unless secondary spread occurs
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Case definition
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Standard set of criteria in deciding whether an individual should be classified as having illness, does not include exposure or risk factor.
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Epi curve
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shows magnitude of cases over time, used in step 6 descriptive epidemiology,
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odds ratio
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A measure of association which quantifies the relationship between an exposure and health outcome from a comparative study; also known as the cross-product ratio
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crude death rate
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Annual number of deaths per 1,000 people in the population of a geographic area at the midpoint of a given year. Does not account for person differences
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Infant mortality
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A figure that describes the number of babies that die within the first year of their lives in a given population.
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child mortality
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A figure that describes the number of babies that die within the first year of their lives in a given population.
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maternal mortality
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Number of deaths per thousand of women giving birth.
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life expectancy
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A figure indicating how long, on average, a person may be expected to live. Normally expressed in the context of a particular state.
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ecological fallacy
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an error in reasoning in which incorrect conclusions about individual-level processes are drawn from group-level data
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experimental epidemiology
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begins with a hypothesis about a particular disease; experiments to test the hypothesis are then conducted with a group of people
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randomized controlled trials
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experimental study in which particpant are randomly assigned to either an experimental or control group to receive different interventions or placebos
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field trials
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Trials to PREVENT disease (Involves HEALTHY people)
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community trials
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Form of experimentation, the treatment groups are communities rather than individuals. Difficult to isolate community for investigation many confounding variables
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Random error
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An error that occurs when the selected sample is an imperfect representation of the overall population
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Sample size
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must be large and representative of the population
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systematic error
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(Bias) results differ in a systematic manner from true values, all too high or all too low
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selection bias
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Errors in the selection and placement of subjects into groups that results in differences between groups which could effect the results of an experiment.
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measurement bias
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Measurements do not correctly/accurately measure what they are intended to measure
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confounding
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A factor other than the independent variable that might produce an effect in an experiment.
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Control confounding by
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Randomizing population and controls, restricting people with particular characteristics, and matching people similarly to ensure populations are nonrandom
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Internal/external validity
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internal: degree by which results of a particular group are correct external: degree by which results of a particular group outside tested are correct
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vectors
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insects or animals that carry infectious agent
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vehicles
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contaminated objects that spread disease. Water, food
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chain of infection
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(1) Agent -> (2) Reservoir in which infectious agent lives -> (3) Portal of exit -> (4) mode of transmission -> (5) portal of entry
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pathogenicity
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Ability to cause disease
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CDC mission
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To protect America from health, safety and security threats, both foreign and in the U.S, by increasing public health awareness, fight diseases, and nurture health care
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Probable case
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These usually have characteristic clinical features of the disease, but lack laboratory confirmation
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Possible case
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These have some of the clinical features
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Confirmed case
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laboratory confirmed cases
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Horizontal transmission
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transmission of microorganisms directly from one individual to another by one or more of the following means: direct and indirect
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Vertical transmission
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transmitted directly from the mother to an embryo, fetus, or baby during pregnancy or childbirth
