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 criterion

An epidemiological link to a confirmed or probable case of mpox.

Clade I criteria

1. Travel history to an area^1,2 where:
2. 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
3. There is a current risk of Clade I virus: Angola, South Sudan, Tanzania, and Zambia

OR

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

OR

An epidemiological link to a confirmed or probable case of clade I MPXV. 

Case classification

Possible/Suspected case:
N/A

Probable case:

Clade II probable 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. Reports a change in sexual partners in the 21 days prior to symptom onset, regardless of sexual practice³

Clade I probable 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.

³ Noting that Clade II infection is more likely if the individual is gay, bisexual or other man who has sex with men ( gbMSM) with recent partner change

Version 2.12
Last updated: 16 September 2024