Monkeypox: case definitions

Possible case

A person with a febrile prodrome^† compatible with monkeypox infection where there is known prior contact with a confirmed case in the 21 days before symptom onset.

Or, a person with an illness where the clinician has a high suspicion of monkeypox (for example, this may include prodrome or atypical presentations with exposure histories deemed high risk by the clinician, or classical rash without risk factors).

^† Febrile prodrome consists of fever ≥ 38°C, chills, headache, exhaustion, muscle aches (myalgia), joint pain (arthralgia), backache, and swollen lymph nodes (lymphadenopathy).

Probable case

A person with a monkeypox compatible vesicular-pustular rash plus at least one of the following epidemiological criteria:

• exposure to a confirmed or probable case in the 21 days before symptom onset

• history of travel to an area where monkeypox is endemic, or where there is a current outbreak in the 21 days before symptom onset (currently West and Central Africa, Spain, Portugal and USA)

• gay, bisexual and other men who have sex with men (GBMSM)

Actions on a possible or probable case

Test for monkeypox (using designated testing pathway).

Undertake additional contemporaneous tests to rule out alternative diagnoses if clinically appropriate and if not done already.

If admission of patient required for clinical reasons, admit to single room isolation at negative or neutral pressure at local hospital site with RPE PPE (with appropriate IPC arrangements).

Or, if patient not requiring admission for clinical reasons: self-isolation at home (based on assessment by the clinician and following UKHSA guidance).

Or, if patient not requiring admission for clinical reasons but self-isolation at home is not possible for social or medical reasons following clinician assessment: isolation in single room at negative or neutral pressure at local hospital site with RPE PPE pending test result (prioritise probable cases).

Confirmed case

A person with a laboratory confirmed monkeypox infection (monkeypox PCR positive).

Action on a confirmed case

Transfer to HCID unit.

Further information

Additional monkeypox resources are available on GOV.UK, including guidance on vaccination.