first set of personal flashcards
Incidence
The number of new cases per person per unit of time
Observational Study
Study in which events occur without the scientist having controlled starting conditions. Resembles the studies of geology and astronomy.
Epidemiology
The study of the distribution and determinants of health-related states or events in specified populations, and the application of this study is the control of health problems.
5 Ws of Descriptive Epidemiology
Diagnosis or health event (what), Person (who), Place (where), Time (when) and Modes of Transmission (why/how)
Frequency
Not only the number of health events, but also the relationship of that number to the size of the population.
Pattern
The occurrence of health-related events by time, place and person.
Descriptive Epidemiology
Characterizing health events by time, place, and person.
Determinants
The causes and other factors that influence the occurrence of disease and other health-related events.
Analytic Epidemiology
Provides the “why” and “how” disease and other health events spread/occur.
Public Health Surveillance
The ongoing, systematic collection, analysis, interpretation, and dissemination of health data to help guide public health decision making and action.
Field Investigation
Characterizes the extent of the epidemic and attempts to identify its cause.
Shoe Leather Epidemiology
Slang; the objective is 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.
Analytic Studies
A study with the purpose of identifying and quantifying the relationship between an exposure and an outcome and to test hypotheses about causal relationships by comparing case-patients and those in an appropriate comparison group (control).
identify relationship btwn exposure and outcome to test hypothesis
Design
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.
Conduct
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.
Analysis
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 computations of measures of association (e.g., chi-square test), confidence intervals, and the like.
Interpretation
Involves putting the study findings into perspective, identifying the key take-home messages, and making sound recommendations. Doing so requires the epidemiologist be knowledgeable about the subject matter and the strengths and weaknesses of the study.
Evaluation
The process of determining, as systematically and objectively as possible, the relevance, effectiveness, efficiency, and impact of activities with respect to establish goals.
Effectiveness
Refers to the ability of a program to produce the intended or expected results in the field.
Efficacy
The ability to produce results under ideal conditions.
Efficiency
Refers to the ability of the program to produce the intended results with a minimum expenditure of time and resources.
Formative Evaluation
Evaluation that focuses on plans.
Process Evaluation
Evaluation that focuses on operations.
Summative Evaluation
Evaluation that focuses on impact.
Linkages
Working in conjunction with members of other disciplines.
Case Definition
A set of standard criteria for classifying whether a person has a particular disease, syndrome, or other health condition.
Rate
The number of cases divided by the size of the population per unit of time.
Secular trends
Long term trends; Assess the prevailing direction of disease occurrence (increasing, decreasing, or essentially flat).
Epidemic Curve
A graph used to show the time course for a disease outbreak or epidemic
Experimental Study
In this type of study, the investigator determines through a controlled process the exposure for each individual (clinical trial) or community (community trial), and then tracks the the individual or communities over time to detect the effects of the exposure.
Cohort Study
In this type of study, and epidemiologist records whether each study participant is exposed or not, and then tracks the participants to see if they develop the disease of interest. Similar to an experimental study, but observes rather than determines the exposure status.
Prospective Cohort Study
A kind of cohort study that observes the exposure status, and tracks the participants to see if they develop the disease in question; Also called a follow-up study
Retrospective Cohort Study
In this type of study, both the exposure and the outcomes have already occurred.
Case-Control Study
In this type of study, epidemiologists start by enrolling a group of people with a disease and a group of people with out that disease (controls). Investigators then compare previous exposures between the two groups.
Case-Patient
A person with the disease of interest. Not called a case because case refers to occurrence of disease rather than a person.
Cross-Sectional Study
In this type of study, a sample of persons from a population is enrolled and their exposures and health outcomes are measured simultaneously. It tends to assess the presence (prevalence) of the health outcome at that point in time without regard to duration.
Epidemiologic Triad
Model of disease causation consisting of an external agent, a susceptible host, and an environment that brings the host and agent together. Works best for infectious diseases.
Agent
An infectious microorganism or parasite, chemical contaminants, or physical force that causes disease or injury.
Host
The human who contracts the disease.
Environment
Refers to the intrinsic factors that effect the agent and the opportunity for exposure.
Causal Pie
A model of disease causation that accounts for the multifactorial nature of causation that represents each individual factor as a piece of the pie. After all the piece fall into place - disease occurs.
Necessary Cause
A component that appears in every pie or pathway. Without it, a disease will not occur.
Incubation Period
Name for the time from exposure to onset of disease symptoms for infectious diseases
Latency Period
Name for the time from exposure to onset of disease symptoms for chronic diseases.
Spectrum of Disease
The range of manifestations a disease process can take (e.g., from asymptomatic to mild clinical illness to severe illness and death).
Prevalence
The proportion of the population at a given time that has a case
Case Fatality Rate
Ratio of fatal cases to total cases
Risk factor
A definable element of exposure that captures at least one part of the pathway by which the cause increases the risk that a member of the population will meet the criteria of a case.
Infectivity
The proportion of exposed person who become infected.
Pathogenicity
The proportion of infected individuals who develop a clinically apparent disease.
Virulence
The proportion of the population of clinically apparent cases that are fatal.
Carriers
Case-patients that are asymptomatic, but can still transmit disease
Reservoir
The habitat in which the agent normally lives, grows, and multiplies.
Zoonosis
An infectious disease that is transmissible under natural conditions from vertebrate animals to humans.
Portal of Exit
The path by which a pathogen leaves its host
Direct Transmission
Transmission in which an infectious agent is transferred from a reservoir to a susceptible host by direct contact or droplet spread
Indirect Transmission
Refers to the transfer of an infectious agent from a reservoir to a host by suspended air particles, inanimate objects (vehicles), or animate intermediaries (vectors).
Direct Contact
Contact that occurs through skin-to-skin contact, kissing, and sexual intercourse. Can also refer to contact with soil or vegetation harboring infectious organisms
Droplet Spread
Refers to spray with relatively large, short-range aerosols produced by sneezing, coughing, or even talking.
Airborne Transmission
Occurs when infectious agents are carried by dust or droplet nuclei suspended in air
Vehicles of Transmission
Include food, water, biologic products (blood), and fomites (inanimate objects such as handkerchiefs, bedding, or surgical scalpels).
Vectors of Transmission
Examples include mosquitoes, fleas, and ticks that may carry an infectious agent through purely mechanical means or may support growth or changes in the agent
Portal of Entry
Refers to the manner in which a pathogen enters a susceptible host.
Herd Immunity
The concept that suggests that if a high enough proportion of the population are resistant to the agent, then the few that are susceptible will be protected by the resistant majority, since the pathogen will be unlikely to “find” those few susceptible individual.
Endemic
The constant presence of an agent or health condition within a given geographic area or population; can also refer to the usual prevalence of an agent or condition.; Baseline
Sporadic
Refers to a disease that occurs infrequently and irregularly
Hyperendemic
Refers to persistent, high levels of disease occurrence.
Epidemic
Refers to an increase, often sudden, in the number of cases of a disease above what is normally expected in that population in that area.
Outbreak
Refers to a sudden increase in the number of cases of disease above the baseline, often limited to a more limited geographic area.
Cluster
Refers to an aggregation of cases grouped in place and time that are suspected to be greater than the number expected, even though the expected number may not be known.
Pandemic
Refers to an epidemic that has spread over several countries or continents, usually affecting a large number of people
Common-Source Outbreak
Outbreak in which a group of persons are all exposed to an infectious agent or a toxin from the same source.
Point-Source Outbreak
Outbreak in which a group of persons are all exposed to an infectious agent or a toxin over a relatively brief period of time so that everyone who becomes ill does so within one incubation period
Continuous Common-Source Outbreak
Outbreaks in which case-patients may have been exposed over a period of days, weeks, or longer, resulting in the flattening and widening of the peaks of the epidemic curve. The range of exposures and range of incubation periods are longer.
Intermittent Common-Source Outbreak
The epidemic curve of this type of outbreak often shows its intermittent nature of this exposure.
Propagated Outbreak
Results from transmission from one person to another. Cases occur over more than one incubation period.
Mixed Epidemic
Epidemic that starts out with a common-source outbreak, followed by person-to-person spread (propagated outbreak).
Distribution
The when (time), place (where), and person (who) of the case.
