In epidemiology, the prevalence of a disease in a statistical population's defined as the total number of cases of the disease in the population at a given time, or the total number of cases in the population, divided by the number of individuals in the population. It's used as an estimate of how common a condition's within a population over a certain period of time. It helps physicians or other health professionals understand the probability of certain diagnoses and's routinely used by epidemio… (More on Prevalence)