Strengthening health security by implementing the International Health Regulations (2005)

Case definitions for the four diseases requiring notification to WHO in all circumstances under the IHR (2005)

Under the International Health Regulations 2005 (IHR 2005), the World Health Organization is to establish case definitions for the following four critical diseases which are deemed always to be unusual or unexpected and may have serious public health impact, and hence must be notified to WHO in all circumstances:

  • smallpox
  • poliomyelitis due to wild type poliovirus
  • human influenza caused by a new subtype, and
  • severe acute respiratory syndrome (SARS).

Note, however, that these case definitions are specifically for purposes of notification under the IHR (2005), and may not apply to other surveillance or reporting systems, which may have their own definitions.

The IHR (2005) also require notification of all (public health) events which may constitute a public health emergency of international concern, in accordance with the Decision Instrument in Annex 2.