National case definition: Mpox (monkeypox)

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Preliminary surveillance case definitions for mpox (monkeypox) in Canada

Suspected case

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

  1. An unexplainedFootnote 1 acute skin rash or lesion(s)Footnote 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
    • Prostration/asthenia (profound weakness)
    • Fatigue
    • Pharyngitis (sore throat)
    • Proctitis (rectal inflammation/pain)
  2. An unexplainedFootnote 1acute genital, perianal, anorectal and/or perioral, oral, or oropharyngeal rash or lesion(s)Footnote 2

Probable case

A person of any age who meets the suspect case definition


Has one or more of the following:

  1. Has an epidemiological link to a probable or confirmed mpox (monkeypox) case in the 21 days before symptom onset
  2. Has an epidemiological link to a location/event where transmission of mpox is suspected or known to have occurred in the 21 days before symptom onset
    An epidemiological link can be:
    • 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

Confirmed case

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


Footnote 1

Common infectious causes of acute rash or lesion(s) 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 or lesion(s)

Mpox illness includes a rash or lesion(s) that can affect the mucous membranes in the oropharynx and anogenital area. The rash or lesion(s) can also affect the face, trunk, limbs, and palms of hands and soles of the feet. The rash or lesion(s) can last for 2 to 4 weeks and may appear as singular or multiple macules, pustules, vesicles, crusted lesions or ulcers. Lesions in varying stages can be present simultaneously. Anorectal lesions can manifest as anorectal inflammation (proctitis), pain and/or bleeding.

N.B. It is not necessary to obtain negative laboratory results for listed infectious causes of rash or lesion(s) in order to classify a case as suspected.

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