National case definition: Plague


Date of last revision/review: May 2008

National notification

Only confirmed cases of disease should be notified.

Type of surveillance

Routine case-by-case notification to the federal level

Case classification

Confirmed case

Clinical evidence of illness with laboratory confirmation of infection:


Probable case

Clinical evidence of illness with any of the following laboratory evidence:





Laboratory comments

Serologic confirmation is done by demonstration of a significant (i.e. fourfold or greater) rise in serum antibody titre to Y. pestis F1 antigen by EIA or passive hemagglutination/inhibition titre.

Clinical evidence

Plague is characterized by fever, chills, headache, malaise, prostration and leukocytosis, and is manifest in one or more of the following principal forms:

ICD code(s)

Type of international reporting

Under Article 6 of the International Health Regulations (IHR) (2005), each State Party shall notify the World Health Organization (WHO) by way of the IHR National Focal Point,Footnote 1 and within 24 hours of assessment of public health information, of all events which may constitute a public health emergency of international concern within its territory in accordance with the decision instrument (Annex 2 of the IHRFootnote 2), as well as any health measure implemented in response to those events.

Note: If event does not meet the criteria for notification under Article 6 of the IHR, then other IHR-related reporting requirements may still apply with WHO and/or other States Parties, including those under Art. 7 (information-sharing during unexpected or unusual public health events), Art. 8 (consultation with WHO on public health events), Art. 9 (any public health risk that may cause international disease spread), Art. 10 (requests for verification from WHO), and Art. 44 (collaboration and assistance).

Elimination or eradication efforts should be reported.


Probable case definitions are provided as guidelines to assist with case finding and public health management, and are not for national notification purposes.


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