a measure of morbidity based on current sickness in a population, estimated either at a particular time (point prevalence) or over a stated period (period prevalence). It can be expressed either in terms of sick people (persons) or episodes of sickness per 1000 individuals at risk. Compare incidence rate.
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the number of people in a population who have a disease or other condition at a given time: the numerator of the rate is the number of existing cases of the condition at a specified time and the denominator is the total population. Time may be a point or a defined interval; if unspecified it is traditionally the former. Cf. incidence r.Medical dictionary. 2011.