Case definition
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Case definition


General principles for the application of these case definitions 

  • Unless specifically stated, only symptomatic cases are to be reported, however, asymptomatic infections are to be regarded as cases, if the infection has therapeutic or public health implications.

  • A ‘case with an epidemiological link’ is a case that has either been exposed to a confirmed case, or has had the same exposure as a confirmed case (e.g. eaten the same food, stayed in the same hotel, etc).

  • A three-tiered system with following levels is to be used:
      1. Confirmed case: verified by laboratory analysis,
      2. Probable case: clear clinical picture, or linked epidemiologically to a confirmed case,
      3. Possible case: indicative clinical picture without being a confirmed or probable case
  • The classification on these different levels might vary according to the epidemiology of the individual diseases.

  • Clinical symptoms listed are only given as indicative examples and not exhaustive.

  • For most diseases, several ‘criteria for laboratory diagnosis’ are listed. Unless otherwise stated, only one of these is needed to confirm a case.

  • N.A. in the case definition list means ‘not applicable’.

Introductory Notes

  1. The information reported in this document is intended only for uniform reporting/comparability of data within the Community network. The clinical description gives a general outline of the disease and does not necessarily indicate all the features needed for clinical diagnosis of the disease.

  2. The laboratory criteria for diagnosis reported here may be fulfilled with different testing methods. However, when specific techniques are indicated, their use is recommended.


Case definitions 2018 - Infectious Disease Prevention and Contol Unit