Mpox: guidance on when to suspect a case of mpox
This guidance describes symptoms of mpox and epidemiological criteria to help inform testing and reporting of suspected cases.
This document provides guidance on when to suspect mpox, the disease caused by any clade of the virus called MPXV. Disease caused by clade I MPXV is managed as a high consequence infectious disease (HCID) in the UK.
When assessing patients for mpox, always take a travel history. There is a current outbreak of HCID (clade I) mpox in the Democratic Republic of the Congo (DRC) and other countries in the African region. Further information on affected countries can be found at Operational mpox HCID (clade I) case definition. Be alert to the possibility of HCID mpox (clade I) in all patients with suspected mpox if they have a travel history to the affected region.
Discuss any cases of mpox that may be HCID (clade I) with your relevant local infection team (infectious diseases, microbiology or virology) who may advise further discussion with the imported fever service (IFS).
Suspected mpox
The possibility of mpox should be considered:
1. where a case presents with a prodrome [note 1] compatible with mpox infection, and where there is known prior contact with a confirmed or suspected case of mpox in the 21 days before symptom onset
or
2. where a case presents with unexplained lesions (for example vesicles, pustules, nodules or ulcers) compatible with mpox anywhere on the body, including but not limited to:
- anywhere on the skin (face, limbs, extremities, torso)
- oral, genital or ano-genital lesions
- proctitis – for example anorectal pain, bleeding
and also one or more of the following apply:
- has an epidemiological link to a confirmed or suspected case of mpox in the 21 days before symptom onset
- has a travel history to specified countries where there may be a risk of clade I exposure within 21 days of symptom onset (see operational HCID case definition)
- identifies as a gay, bisexual or other man who has sex with men (GBMSM)
- has had 1 or more new sexual partners in the 21 days before symptom onset
- has none of the above risk factors, but has been discussed with local infection services (infectious diseases, microbiology, virology or sexual health as appropriate) and investigated locally for common diagnoses [note 2] without a cause identified
- has a relevant zoonotic link, including contact with a wild or captive mammal that is an African endemic species (this includes derived products, for example, game meat)
Note 1: Prodrome consists of fever, chills, headache, exhaustion, muscle aches (myalgia), joint pain (arthralgia), backache, and swollen lymph nodes (lymphadenopathy).
Note 2: Common diagnoses include, but are not limited to: chickenpox or varicella zoster virus (VZV), herpes simplex (HSV) and enterovirus.
Actions for a suspected case of mpox
For cases meeting the operational HCID case definition
The managing clinician should contact their relevant local infection team (infectious diseases, microbiology, or virology). Local infection team to then to discuss with the IFS (0844 778 8990) who will review risk assessment and advise on the next steps for investigation and management.
For cases that do not meet the operational HCID case definition
Test for MPXV, the causative agent of mpox (using designated testing pathway). See also Mpox diagnostic testing guidance.
Undertake additional contemporaneous tests to rule out alternative diagnoses if clinically appropriate and if not done already.
If admission of patient is required for clinical reasons, IPC measures should be undertaken as per the national IPC manual.
If patient not requiring admission for clinical reasons: self-isolation at home (based on assessment by the clinician and following UKHSA guidance.
If admission of patient is not required for clinical reasons, but self-isolation at home is not possible for social or medical reasons following clinician assessment, patient should be admitted pending test result, with IPC measures undertaken as per the national IPC manual.
Highly probable case
A highly probable case is defined as a person with an orthopox virus PCR positive result where mpox remains the most likely diagnosis.
Confirmed case
A confirmed case is defined as a person with a laboratory-confirmed mpox infection (MPXV PCR positive).
Actions for a confirmed or highly probable case
All confirmed or highly probable cases should be assessed for the need for admission based on either clinical or self-isolation requirements. The NHS provides guidance on management of patients with confirmed mpox.
All confirmed and highly probable cases, or suspected cases undergoing testing should be notified to the local health protection team by the clinician; there is a statutory obligation for clinicians to make a clinical notification to the health protection team if it is believed that the diagnosis is mpox.
Further information
Additional mpox resources are available on GOV.UK, including guidance on vaccination and contact tracing.
Updates to this page
Last updated 12 September 2024 + show all updates
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Probable and possible case definitions combined into one suspected case definition. Added actions for those managing a suspected case of HCID mpox.
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Updated to include HCID mpox (Clade I) and link to operational HCID definition.
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Updated in line with the HCID derogation of Clade II mpox.
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Updated actions on a possible or probable case.
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Added highly probable case definition, and amended actions for confirmed or highly probable cases. Updated possible and probable case definitions.
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Removed requirement to notify HCID network about all confirmed cases. Added link to NHS pages on management.
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Updated actions for confirmed cases.
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Updated probable case information.
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Added links to additional monkeypox guidance.
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First published.