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Under the terms of the International Health Regulations (2005) (IHR (2005)), the World Health Organization (WHO) is to establish case definitions for the following 4 critical diseases that 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). 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 that may constitute a public health emergency of international concern, in accordance with the Decision Instrument.

Case definition for notification of poliomyelitis due to wild-type poliovirus under the IHR (2005)

Source:WHO. Weekly Epidemiological Record. No. 7, 2009 (13 Feb 2009), 84, 52-56. Available at: http://www.who.int/wer

Under the IHR (2005), a notifiable case of poliomyelitis due to wild-type poliovirus is defined as a suspected case, with isolation of wild poliovirus in stool specimens collected from the suspected case or from a close contact of the suspected case. A suspected case is defined as a child aged <15 years presenting with acute flaccid paralysis (AFP), or as an individual of any age presenting with paralytic illness if poliomyelitis is suspected.

Note concerning notification of wild-type or vaccine-derived poliovirus from sources other than AFP cases

In addition to notification of laboratory-confirmed cases of poliomyelitis due to wild-type poliovirus (a disease designated in Annex 2 of the IHR (2005) as "unusual or unexpected and that may have serious public health impact"), the isolation of wild-type or vaccine-derived poliovirus from other human or non-human sources (from people without paralysis, or from environmental samples) must generally also be notified to WHO under the separate notification requirement for "events that may constitute a public health emergency of international concern" as they fulfill at least 2 of the 4 criteria for notification.