An epidemic curve is a graph of case onset over time. What information can it provide?

• A. A graph of case onset over time that helps identify outbreak pattern, possible source, and incubation periods
• B. A map of disease distribution by location
• C. A chart of vaccination coverage
• D. A schedule of prevention activities

Answer: (A)

An epidemic curve shows when cases began over time, giving a clear view of how the outbreak evolves. This time-based pattern helps you identify the outbreak’s shape: a sharp, single peak suggests a point-source exposure; a gradual rise and fall points to a prolonged or continuous exposure; several peaks indicate ongoing transmission between people. By examining the interval between exposure and illness, you can estimate incubation periods and the speed of spread, which narrows down likely sources and modes of transmission. This temporal insight is useful for guiding control measures to stop further transmission. A geographic distribution map would be needed to show where cases occurred. A chart of vaccination coverage or a plan of prevention activities are separate types of information not depicted by the curve.