Case definition includes which element?

• A. a list of collected data items
• B. follow-up policy
• C. identification of population covered
• D. security control provisions

Answer: (C)

A case definition is the set of criteria used to decide whether a person is considered a case for surveillance. A key part of that definition is specifying who is included—the population covered. This sets the scope so that cases are counted consistently across time and places (for example, all residents of a city during a certain period or all patients in a particular clinic). Without defining the population, the same symptoms or lab results could be applied to different groups, making data incomparable.

The other elements listed—a list of data items to collect, follow-up policy, and security controls—pertain to how data are gathered, managed, and protected, or to post-detection actions, rather than to the criteria that determine who qualifies as a case.