Prevalence is defined as the?

• A. The rate of disease mortality
• B. The number of existing cases of a disease or health condition in a population at a designated time
• C. The number of new cases during a time period
• D. The proportion of people with a given risk factor

Answer: (B)

Prevalence measures the burden of disease in a population at a specific moment. It is the number of existing cases of a disease or health condition in a population at a designated time. This distinguishes it from incidence, which counts new cases that develop over a period. The statement that refers to the number of people who already have the disease at a defined time matches this idea. Mortality rate tracks deaths, not how many people are living with the disease; the count of new cases describes incidence; and a proportion of people with a risk factor describes risk-factor prevalence rather than disease prevalence.