Prevalence

Prevalence is an epidemiological measure of the proportion of a population with a disease or a particular health condition at a specific point in time (point prevalence) or over a specified period of time (period prevalence).

Tuberculosis (TB) prevalence refers to the number of people with TB that are present in a particular population at a given time. Calculation of the TB prevalence rate is shown in the figure below.

Figure: Deriving the Prevalence of TB Disease for a Given Population

TB prevalence rate is derived by adding the number of persons that develop new TB disease (i.e., incident cases​) and those who already have the disease (i.e., existing cases), and dividing the sum by the total population from which the cases arose.

TB prevalence varies widely and is affected by a number of factors such as age, gender, population density, rural/urban settings, as well as socioeconomic factors.

Resources

• Epidemiologic Basis of Tuberculosis Control, Hans L. Rieder, 1999.

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