In a stable situation-

prevalence refers specifically to all current cases existing at agiven point in time ,or over a period of time in a given population. Prevalence depends on 2 factors,incidence and duration of disease. Given assumption that the population is stable,and incidence and duration are unchanging ,the relationship between incidence and prevalence can be expressed as P=I*D = incidence *mean duration. Parks textbook of preventive and social medicine.K Park. Edition 23.Pg no: 61