Following the activation of the OICC, investigation partners must agree on case definitions. Case definitions are a set of standard criteria to determine who should be included as part of an outbreak and who should not. The purpose is to ensure that cases are counted in a systematic and consistent manner in order to make comparisons and analyze trends.
In outbreak investigations, case definitions are only used for counting outbreak cases, not for establishing clinical diagnoses, or to make healthcare decisions for an individual patient. Existing guidelines, algorithms, and protocols should be followed as per local jurisdictional policies for appropriate clinical case management.
There are two components that should be included in case definitions:
- Clinical and/or laboratory criteria to assess if an individual has the illness of interest, and
- Restrictions by person, place, and time.
Case definitions are often refined to be more specific during the course of an investigation when new information becomes available (Further reading: Case definitions).
Question 2-2: Create a draft confirmed case definition for this outbreak.
Question 2-3: It is decided that a confirmed case definition is all that is required for this investigation. However, other investigations may include ‘probable’ and ‘suspect’ case definitions. Why might you want a probable case definition for this investigation? Draft a probable case definition that could be used.
Further information on case definitions, including probable and suspect case definitions, is available here.