TEXAS REGISTERED SANITARIAN - QUICK EPIDEMIOLOGY REVIEW|2023/24 UPDATE|GRADED A+

What is epidemiology? Epidemiology is 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. What is a case definition? A case definition is a set of standard criteria for classifying whether a person has a particular disease, syndrome, or other health condition Describe the difference between descriptive and analytic epidemiology Descriptive epidemiology provides a way of organizing and analyzing data on health and disease in order to understand variations in disease frequency geographically and over time and how disease varies among people based on a host of personal characteristics (person, place, and time). Analytic epidemiologic studies measure the association between a particular exposure and a disease, using information collected from individuals, rather than from the aggregate population. What is a cohort study? In a cohort 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 What is a case-control study? In a case-control 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. What is a cross-sectional study? A sample of persons from a population is enrolled and their exposures and health outcomes are measured simultaneously. The cross-sectional study tends to assess the presence (prevalence) of the health outcome at that point of time without regard to duration. Explain the difference between infectivity, pathogenicity and virulence If an agent is very infective, a larger proportion of hosts will be infected by it. If an agent is very pathogenic, then a higher proportion of the infected will develop clinically apparent disease If an agent is very virulent, then a higher proportion of clinically apparent cases will develop severe disease or die What is a carrier? A person who is infectious, but has subclinical disease What does it mean when a disease is endemic? Endemic refers to the amount of disease that is usually present in a community/geographic area, aka the baseline What does it mean when a disease is sporadic? A sporadic disease occurs infrequently or irregularly What does it mean when a disease is hyperendemic? A hyperendemic disease refers to persistent, high levels of disease occurrence What does it mean when a disease is epidemic? 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. What is an outbreak? An epidemic localized to a more limited geographic area. What is a cluster? 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. What is a pandemic? Pandemic refers to an epidemic that has spread over several countries or continents, usually affecting a large number of people What are some factors that could contribute to an epidemic? A recent increase in the amount or virulence of an agent A recent introduction of the agent to a new area An enhanced mode of transmission that exposes more people A change in the susceptibility of the host to the agent What is a common-source outbreak? A common-source outbreak is one in which a group of persons are all exposed to an infectious agent or a toxin from the same source When does a common-source outbreak become a point-source outbreak? If the group is exposed over a relatively brief period, so that everyone who becomes ill does so within one incubation period, then the common-source outbreak is further classified as a point-source outbreak Describe the difference between a continuous and intermittent common-source outbreak and how they will change an epidemic curve In a continuous common-source outbreak, the range of exposures and range of incubation periods tend to flatten and widen the peaks of the epidemic curve The epidemic curve of an intermittent common-source outbreak often has a pattern reflecting the intermittent nature of the exposure