The number of cases of infection in relation to the unit of population in which they occur (a static measure) at different times of the year.
The number of events, such as instances of a given disease, condition or other attribute, present at a particular time. Sometimes used to mean prevalence rate. When used without qualification, the term usually refers to the situation at a specified point in time (point prevalence). annual prevalence: The total number of persons with a given disease or attribute at any time during a year. lifetime prevalence: The total number of persons known to have had a given disease or attribute for at least part of their lives. period prevalence: The total number of persons known to have had a given disease or attribute at any time during a specified period. point prevalence: The total number of persons with a given disease or attribute at a specified point in time. See also “incidence”.... prevalence
Known colloquially as SADS, this is a disorder in which an affected individual’s mood changes with the seasons. He or she is commonly depressed in winter, picking up again in the spring. The diagnosis is controversial and its prevalence is not known. The mood-change is probably related to light, with MELATONIN playing a key role. (See also MENTAL ILLNESS.)... seasonal affective disorder syndrome
quotient using as the numerator, the number of persons sick or portraying a certain condition, in a stated population, at a particular time, regardless of when that illness or condition began, and as the denominator, the number of persons in the population in which they occurred.... prevalence rate
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