Mpox (monkeypox) Case Definition

Mpox (monkeypox) Case Definition -

Clinical criteria

A person with, or who has had, one or more of the following:

• Unexplained recent onset rash which may include single or multiple lesions in the ano-genital region or elsewhere on the body.
• Mucosal lesions – single or multiple lesions which may be oral, conjunctival, urethral, penile, vaginal or anorectal.
• Proctitis (rectal pain/tenesmus/rectal bleeding).
• One or more classical symptom(s) of mpox (monkeypox) infection - acute illness with fever (>38.5◦C), headache, myalgia, arthralgia, back pain, lymphadenopathy, asthenia, fatigue.

Laboratory criteria

General criterion Detection of monkeypox virus (MPXV)-specific DNA sequences by polymerase chain reaction (PCR) and/or by sequencing of a clinical specimen. Clade II specific criterion Detection of MPXV Clade II-specific DNA sequences by PCR and/or by sequencing of a clinical specimen. Clade I specific criterion Detection of MPXV Clade I-specific DNA sequences by PCR and/or by sequencing of a clinical specimen.

Epidemiological criteria

At least one of the following epidemiological links in the 21 days before symptom onset: Clade II criteria An epidemiological link to a confirmed or probable case of mpox. Clade I criteria 1. Travel history to an area^1,2 where:

• There is evidence of sustained human to human transmission of clade I MPXV or where clade I MPXV is currently endemic: DRC, Republic of Congo, Central African Republic, Burundi, Rwanda, Uganda, Kenya, Cameroon and Gabon
• There is a current risk of Clade I virus: Angola, South Sudan, Tanzania, and Zambia

OR 2. A person who has had close or intimate in-person contact with individuals in a social network currently experiencing clade I MPXV activity OR 3. An epidemiological link to a confirmed or suspected case of mpox from clade I affected countries OR 4. An epidemiological link to a confirmed or probable case of clade I MPXV.

Case classification

Possible/Suspected case: N/A Probable case: Clade II case classification Any person meeting the clinical criteria and at least one of the following: 1. has an epidemiological link to a confirmed or probable case of mpox in the 21 days before symptom onset 2. identifies as a gay, bisexual or other man who has sex with men (gbMSM) 3. has had multiple and/or casual sexual partners in the 21 days before symptom onset. Clade I case classification Any person meeting the clinical criteria and at least one of the Clade I Epidemiological Criteria (above). Confirmed case: Any person meeting the laboratory criterion. *Please note* - Mpox is an evolving situation, particularly following the WHO’s declaration of Clade I mpox as a Public Health Emergency of International Concern (PHEIC) on August 14th, 2024. This case definition reflects the current understanding of the situation and may be updated as new information emerges.

Footnotes

¹Up to date information regarding the global distribution of reported mpox clades may be found on the WHO website at https://worldhealthorg.shinyapps.io/mpx_global/. ²Up to date information regarding the global distribution of reported mpox clades and a list of “at risk” countries can be found on the UKHSA website at: https://www.gov.uk/guidance/operational-mpox-monkeypox-hcid-case-definition. Version 2.11 Last updated: 5 September 2024

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