Key Epidemiological Terms

Patterns of Infectious Disease

Endemic

Three key terms are used to describe basic patterns of infectious disease occurrence. The terms are defined by the American Public Health Association (APHA) as:

Endemic: The habitual presence of a disease within a given geographic area; may also refer to the usual prevalence of a given disease within such an area.

Example: Campylobacter is a bacterium that causes acute enteric disease (diarrhea, abdominal pain, malaise, fever, nausea and vomiting). It is usually transmitted through contaminated food, water or raw milk. This disease is endemic in Missouri and throughout much of the US. Each year since 1990, there have been between 535 and 745 cases reported in Missouri. In 2004, cases were reported in 95 counties and the City of St. Louis.