Case Definition

The case definition is the list of specific criteria used to decide whether or not a person has the disease of concern.

Data collection should not start until the case definition has been established because the case definition determines the data needed in order to classify persons as affected or unaffected.

The case definition is based on:

1. Clinical criteria (signs and symptoms found upon physical examination of cases)
2. Distribution of cases with person, place, and time (PPT)