Which statement best describes a disease that continuously exists in a population at a relatively constant frequency?

• A. Endemic
• B. Epidemic
• C. Pandemic
• D. Sporadic

Answer: (A)

This item tests how disease frequency in a population is described over time. When a disease is always present at a relatively stable level in a population, we call it endemic. The background level persists year after year, with only modest fluctuations due to factors like seasonality or changing immunity. For example, a region with constant, ongoing transmission of malaria reflects an endemic pattern, where cases are expected to occur regularly rather than disappearing.

By contrast, an epidemic occurs when cases surge above the expected baseline in a specific area for a period of time, while a pandemic means that surge spans multiple regions or countries. Sporadic describes isolated, irregular cases with no sustained transmission. So the description of continuous existence at a relatively constant frequency fits endemic.