Case definition is a set of criteria to classify wether a person have the health condition of interest or not. The case definition should be set in the context of time, place and person. The time disease has occurred, location and which individuals it is s affecting.
For example, case definition outbreak of cholera in Mugadishu.
Loose, watery stool more than 3 times associated with vomiting, in mugadishu from 1st November to 31st November 2021.