Last revised by Frank Gaillard on 15 Jun 2023

Prevalence is an epidemiological term referring to the proportion that reflects the total disease/condition burden in a population at a specific time and should not be confused with incidence.

There are different kinds of prevalence:

  • point prevalence is the amount of disease at one point in time

  • period prevalence is prevalence over a specific period of time

  • lifetime prevalence relates to events over the entire lifetime of people in a population

Underlying many statistical methods, including the application of Bayes theorem to clinical practice, is the assumption that changes in prevalence do not alter the sensitivity or specificity of a test. In practice, however, this does not seem to always hold true 2.

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Cases and figures

  • Map of global prevalence of tuberculosis
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