The number of existing cases of a disease at a given place and time per the size of the population. Usually measured in the number of cases per 1,000 in a population.
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.