Descriptive epidemiology uses observational studies of the distribution of disease in terms of person, place, and time.

Epidemiology is the study of the distribution of diseases and other health-related conditions in populations, and the application of this study to control health problems.

Three major types of epidemiologic studies are cohort, case-control, and cross-sectional studies (study designs are discussed in more detail in IOM, 2000).

Analytic epidemiologic studies measure the association between a particular exposure and a disease, using information collected from individuals, rather than from the aggregate population.

In summary, the purpose of an analytic study in epidemiology is to identify and quantify the relationship between an exposure and a health outcome. The hallmark of such a study is the presence of at least two groups, one of which serves as a comparison group.

The epidemiologic triangle is made up of three parts: agent, host and environment.

The Triangle has three corners (called vertices): 1. Agent, or microbe that causes the disease (the “what” of the Triangle) 2. Host, or organism harboring the disease (the “who” of the Triangle) 3.

Tee: In 1928, in the Cutter Lecture at Harvard, Wade Hampton Frost introduced the epidemic triad. The lecture was published in AJE in 1976. In 1975, Dr. Jerry Morris, a prominent British epidemiologist, set out a list of seven uses of epidemiology.

Ebola can spread when people come into contact with infected blood or body fluids. Ebola poses little risk to travelers or the general public who have not cared for or been in close contact (within 3 feet or 1 meter) with someone sick with Ebola.

The number of deaths from Covid-19 in Africa—more than 11,950—exceeded the total number of people who died during the largest-ever Ebola outbreak in West Africa, according to the World Health Organization.