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 guidance is for healthcare professionals on when to suspect mpox, the disease caused by any clade of the virus called MPXV. Clade II mpox has been circulating in the UK and globally since 2022 predominantly in gay, bisexual or other men who have sex with men, but remains uncommon. Since 2022, it is no longer classified as a high consequence infectious disease (HCID).
Clade I mpox includes clade Ia, present in central Africa, and clade Ib, which in 2024 to 2025 has caused an outbreak in multiple countries (see the affected country list). Clade I mpox was classified as an HCID until early 2025. Following advice from the Advisory Committee on Dangerous Pathogens (ACDP), it is no longer classified as an HCID.
Clinical assessment
Consider mpox where a case presents with:
1. a prodrome (fever, chills, headache, exhaustion, myalgia, arthralgia, backache, lymphadenopathy), in an individual with contact with a confirmed or suspected case of mpox in the 21 days before symptom onset
Or:
2. an mpox-compatible rash anywhere on the skin (face, limbs, extremities, torso), mucosae (including oral, genital, anal), or symptoms of proctitis, and at least one of the following in the 21 days before symptom onset:
- recent new sexual partner
- contact with known or suspected case of mpox
- a travel history to a country where mpox is currently common - this does not include people transiting through the affected country where they do not leave the airport
- link to an infected animal or meat
Or:
3. an mpox-compatible rash anywhere on the skin (face, limbs, extremities, torso), mucosae (including oral, genital, anal), or symptoms of proctitis, where there is no risk factor and no alternative common differential diagnosis [note 1]. These patients should be discussed with local infection services to determine the approach to investigation and management.
Note 1: alternative common differential diagnoses include varicella zoster virus (which causes chickenpox and shingles), herpes simplex virus, enterovirus (which causes hand, foot and mouth disease), and bacterial infections such as staphylococcal and streptococcal infections.
Actions for a case of mpox
For all suspected mpox cases
For patients being assessed for suspected mpox, infection prevention and control (IPC) measures should be undertaken per the NHS national infection prevention and control manual for England.
Clinicians should be aware that mpox is a notifiable disease.
Clinicians treating patients with suspected mpox should discuss the case with local infection specialists. Infection specialists may wish to discuss possible mpox cases with the UKHSA Imported Fever Service (IFS) on 0844 778 8990 for clinical advice, for example in patients who are severely immunocompromised or pregnant, paediatric patients, or patients from a high risk setting such as shared accommodation.
Test for MPXV, the causative agent of mpox using an appropriate testing pathway. See also Mpox diagnostic testing guidance.
Undertake testing for other diagnoses if clinically appropriate and if not done already.
If the patient requires admission, IPC measures should be undertaken per the national IPC manual.
If the patient does not require admission, they should be advised to self-isolate following UKHSA guidance).
For confirmed cases
A confirmed case is defined as a person with a laboratory-confirmed mpox infection (MPXV PCR positive). Confirmed cases should be notified urgently to the health protection team (HPT). Further guidance on contact tracing, guidance for those isolating at home, and de-isolation and discharge is available.
Most patients who have mild symptoms and who are able to self-isolate can be managed as outpatients with follow-up via a virtual ward or similar, by local infection services or sexual health services.
For severe cases (suspected or confirmed)
The managing clinician should contact their local infection team (infectious diseases, microbiology, virology). If needed, the local infection team can discuss with the Imported Fever Service (0844 778 8990) for advice on the next steps for investigation and management, including the need for admission and treatment.
The NHS in all 4 nations will continue to draw on the expertise of HCID units in the assessment and management of cases requiring admission to hospital. This reflects the potential for severe disease due to any clade in vulnerable groups. In addition, there may be specific infection control risks in patients with extensive disease where input from the HCID network may be helpful.
Further information
Additional mpox resources are available on GOV.UK, including guidance on vaccination.
Updates to this page
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Guidance updated in line with the derogation of clade I mpox.
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Updated HCID operational case definition regarding people transiting through an affected country.
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Minor update to reflect the first detection of clade I mpox in the UK.
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Added information on when to consider clade I (HCID) mpox, and updated information on when to suspect mpox and actions for a suspected case
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Updated links to direct to the NHS guidance on IPC measures for mpox cases in healthcare settings, and to the Green Book chapter 29.
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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.