The list of diseases notifiable to the OIE is reviewed on a regular basis, and exclusions and new inclusions are adopted by the World Assembly of OIE Delegates at its General Session every year.

It is important that OIE Members share a common understanding of what constitutes a ‘case’ for the purposes of notification – the case definition – so that the occurrence and distribution of confirmed cases can be notified consistently among Members and over time. The Terrestrial Animal Health Code (Terrestrial Code) does not yet include a case definition for all OIE-listed terrestrial diseases, which could result in poor or inconsistent notification of disease events. To address this, and to assist Members in meeting their notification obligations, the OIE is working in collaboration with subject-matter experts to develop case definitions for those OIE-listed diseases where this information is absent or incomplete in the Terrestrial Code. The case definitions will eventually be incorporated in the Terrestrial Code through the OIE standard-setting process, in accordance with the prioritised work programme of the Terrestrial Animal Health Standards Commission. In the interim they will be made publicly available on the OIE website after the endorsement of the Scientific Commission for Animal Diseases.

The development of these case definitions supports the initiative of the OIE to codify information included in notifications submitted by OIE Members in the World Animal Health Information System (OIE-WAHIS). Accurate codification allows identification and consistent classification of core information, key components of which (including pathogenic agent and host species) are captured by the case definitions.