What does prevalence measure?

• A. Proportion of individuals with disease at a given time
• B. The rate of new cases per year
• C. Mortality rate
• D. Recovery rate

Answer: (A)

Prevalence measures the proportion of people in a population who have the disease at a specific moment (point prevalence) or during a defined period (period prevalence). It’s a snapshot of disease burden, calculated as existing cases divided by the total population. It’s not about new cases—incidence—which tracks how fast new cases arise over time. It also isn’t a mortality rate (deaths per population) or a recovery rate (proportion who recover). Prevalence reflects who currently has the condition, and it is influenced by how long people remain diseased and by deaths or cures that remove people from the diseased pool.