A sizable number of passengers on a Disney Cruise recently developed symptoms consistent with a gastrointestinal illness. As the ship epidemiologist you suspect norovirus; however, testing for this virus is not readily available at the next island port. You need to develop a case definition to continue the investigation and identify protective measures to stop the spread.

Your case definition at this point should include, at a minimum:

Clinical criteria, plus a specification of time, place and person

Clinical features, plus the exposure(s) you most suspect

Suspect cases

A case definition is not possible without laboratory confirmation