Mpox (monkeypox): symptoms, how it spreads, vaccination and what to do

Mpox is an infection caused by the MPXV virus. UKHSA explains that it was first identified in 1958 in monkeys kept for research, that the first human case was recorded in 1970 in the Democratic Republic of the Congo, and that for many years human cases were mainly linked to contact with infected animals and then to spread between people in close contact. The disease was renamed from monkeypox to mpox.

Two major groups of the virus exist, called clades. UKHSA says clade I (formerly the Central African or Congo basin clade) divides into Ia and Ib, and clade II (formerly West African) into IIa and IIb. Since May 2022, cases have been reported in many countries without a history of the virus, mostly caused by clade IIb lineage B.1 and spread mostly by sexual contact, and since August 2024 clade Ib has also been reported outside Africa, including in the UK, spreading through close physical contact both sexual and non-sexual.

The NHS adds that the UK cases have mainly been clade 2, with a very small number of clade 1.

UKHSA states that mpox does not spread easily between people unless there is close contact. The NHS lists the main routes: close physical contact with the rash, blisters or scabs (including sexual contact, kissing, cuddling and other skin-to-skin contact), touching clothing, bedding or towels used by someone with mpox, and the coughs or sneezes of an infected person who is close to you. UKHSA also lists contact with body fluids such as saliva, nasal mucus, semen or vaginal fluids, and notes limited evidence that close, prolonged face-to-face contact might spread it.

Animals can also pass it on. The NHS says mpox has not been found in animals in the UK, but it can be caught from infected animals, usually rodents, through bites, touching fur, skin, blood or body fluids, or eating meat that has not been cooked thoroughly. UKHSA names rodents as the believed main animal source.

The first symptoms listed by the NHS are a high temperature or feeling hot, cold or shivery, headache, muscle aches, backache, swollen glands, chills, exhaustion and joint pain. You may not get all of them. The rash follows 1 to 5 days later, may be anywhere, and can come with anal pain or bleeding from the bottom.

The rash starts as raised spots that become ulcers or small fluid-filled blisters, which form scabs that later fall off. It is sometimes mistaken for chickenpox. UKHSA notes that the lesions change through stages, different stages can be present at once, redness or darker patches may surround them, and lesions on black or brown skin may be harder to see. Some people do not have a widespread rash and in some cases only genital lesions are present.

The NHS advises calling NHS 111 if you have a rash with blisters or sores and have travelled to an area with mpox in the past 3 weeks, or have had close contact, including sexual contact, with someone with mpox symptoms who travelled to such an area. You should stay at home and avoid close contact, including sharing towels or bedding, until you have been told what to do, and tell the adviser about your travel.

It advises calling a sexual health clinic, ringing ahead before visiting, if you have a rash with blisters or sores and have had one or more new sexual partners in the past 3 weeks, or sex or sexual contact with someone who has symptoms of mpox but has not travelled. If you cannot reach a clinic, the NHS says to stay at home and call 111. The NHS also says 111 can advise if you have a rash but none of these circumstances apply.

UKHSA says diagnosis can be difficult because mpox is often confused with infections such as chickenpox. A confirmed diagnosis needs assessment by a health professional and specific testing in a specialist laboratory, and positive samples are normally sent for clade testing as part of surveillance.

Treatment is mainly supportive, meaning it targets symptoms while the body fights the infection. UKHSA says antiviral drugs such as cidofovir and tecovirimat can be used for people with severe disease or at high risk of severe disease. The NHS says most people get better within a few weeks, but if symptoms are more severe you may need hospital treatment, with higher risk for older people, young children and people whose immune system is affected by a condition or medicine. Decisions about antivirals belong to specialist teams.

If you are told to isolate, it is because the infection passes on through close contact. The NHS points to GOV.UK advice for people isolating at home.

The NHS lists practical steps: get vaccinated if offered, wash hands with soap and water or use alcohol-based sanitiser, watch for symptoms for 3 weeks after returning from an affected area, talk to sexual partners about their health and symptoms, and pause sex and intimate contact if you have symptoms until a doctor tells you that you cannot pass it on. It advises against sharing bedding or towels with someone who may have mpox, close contact within 1 metre with people who may have it, going near wild or stray animals in central or east Africa, and eating or touching wild animal meat there. TravelHealthPro covers the risk in specific countries.

The NHS says the vaccine is offered to people at increased risk, including men who have sex with men and have multiple partners, take part in group sex or attend sex-on-premises venues (staff at those venues may also be eligible), and people who have had or will have close contact with someone with mpox or have a high risk of exposure. UKHSA notes that smallpox vaccine can reduce the likelihood of infection in high-risk groups and that people vaccinated against smallpox, including in childhood, may have milder disease. Eligibility criteria are set nationally and can change, so check current NHS information.