National case definition: Monkeypox

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Preliminary surveillance case definitions for monkeypox in Canada

Suspected case

A person of any age who presents with one or more of the following:

  1. An unexplainedFootnote 1 acute rashFootnote 2 AND has at least one of the following signs or symptoms
    • Headache
    • Acute onset of fever (>38.5°C),
    • Lymphadenopathy (swollen lymph nodes)
    • Myalgia (muscle and body aches)
    • Back pain
    • Asthenia (profound weakness)
  2. An unexplainedFootnote 1 acute genital, perianal or oral lesion(s)

Probable case

A person of any age who presents with an unexplainedFootnote 1 acute rash or lesion(s)Footnote 2

AND

Has one or more of the following:

  1. Has an epidemiological link to a probable or confirmed monkeypox case in the 21 days before symptom onset, such as
    • face-to-face exposure, including health workers without appropriate personal protective equipment (PPE)
    • Direct physical contact, including sexual contact; or contact with contaminated materials such as clothing or bedding
  2. Reported travel history to or residence in a location where monkeypox is reportedFootnote 3 in the 21 days before symptom onset.

Confirmed case

A person who is laboratory confirmed for monkeypox virus by detection of unique sequences of viral DNA either by real-time polymerase chain reaction (PCR) and/or sequencing.

Footnotes

Footnote 1

Common causes of acute rash can include Varicella zoster, herpes zoster, measles, herpes simplex, syphilis, chancroid, lymphogranuloma venereum, hand-foot-and-mouth disease

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Footnote 2

Acute rash
Monkeypox illness includes a progressively developing rash that usually starts on the face and then spreads elsewhere on the body. The rash can affect the mucous membranes in the mouth, tongue, and genitalia. The rash can also affect the palms of hands and soles of the feet. The rash can last for 2 to 4 weeks and progresses through the following stages before falling off:

  • Macules
  • Papules
  • Vesicles
  • Pustules
  • Scabs

N.B. It is not necessary to obtain negative laboratory results for listed common causes of rash illness in order to classify a case as suspected.

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Footnote 3

Reported travel history includes regional, national, or international travel in the 21 days before symptom onset to any area where monkeypox may be reported.

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