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 area1,2 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