Mpox

Mpox is an infectious disease caused by the virus MPXV. Other diseases in the same family include variola virus (which causes smallpox), vaccinia virus and cowpox virus.

The first human case of mpox was recorded in 1970 in the Democratic Republic of the Congo (DRC) and since then the infection has been reported in a number of African countries. Prior to 2022 most cases were reported from the DRC and Nigeria. While the natural reservoir of MPXV remains unknown, it was mainly spread by African rodents, such as rats, mice, and squirrels.

Mpox outbreaks are caused by different types of MPXV called clades.

From May 2022, there was multi-country outbreak of clade II mpox across a range of countries where the virus had not been seen before. This was declared as a Public Health Emergency of International Concern (PHEIC) in July 2022. This PHEIC was declared over by WHO in May 2023 following the global decline in clade II mpox cases.

A different mpox clade, clade I, which causes more severe illness than other mpox clades has also historically been reported in some countries in Central Africa. An outbreak caused by the clade Ib mpox has been occurring in the DRC since 2023, and in some other countries bordering the DRC in 2024. As of August 2024, two exported cases have also been detected outside of the African Region.

The WHO declared another PHEIC on 14 August 2024 due to the rapid increase in confirmed mpox cases in the DRC caused by clade Ib and concerns about spread to neighbouring countries.

Mpox can spread when a person comes into close contact with an infected animal human or with contaminated material. The virus enters the body through broken skin (even if not visible), the respiratory tract or the mucous membranes (eyes, nose, or mouth).

The incubation period (time from infection to first symptoms) for mpox is between five and 21 days. Symptoms usually begin with fever, headache, muscle/backache, joint pain, swollen lymph nodes, chills and exhaustion. During this time a person may be infectious.

Between one to five days after the fever appears, a rash develops, often starting on the face and spreading to other parts of the body. This rash goes through different stages, ending with a scab that later falls off. People are contagious until all their scabs fall off and skin underneath is intact. Scabs may also be infectious.

Mpox is usually a self-limiting illness with mild symptoms. Most people fully recover after several weeks, without any treatment. However, severe illness, which can be fatal, is a risk for some people. Mpox treatment is mainly supportive. Antiviral drugs can be used to treat severe disease or given to people at high risk of severe disease.

Mpox infection whilst pregnant can be dangerous for the baby, leading to loss of the pregnancy, still birth, death in the newborn, or complications for the mother.

Mpox does not spread easily between people unless there is close contact.

Spread between people may occur through:

direct contact with rash, skin lesions or scabs (including during sexual contact, kissing, cuddling or other skin-to-skin contact)
contact with bodily fluids such as saliva, snot or mucous
contact with clothing or linens (such as bedding or towels) or other objects and surfaces used by someone with mpox

It is possible that clade I mpox may spread between people through close and prolonged face-to-face contact such as talking, breathing, coughing, or sneezing close to one another. However, there is currently limited evidence so this will be updated as new information is available.

Spread of mpox may also occur when a person comes into close contact with an infected animal. Mpox has not been detected in animals in the UK.

Prevention

Risk of mpox is low for most travellers. This risk can be reduced by taking the following steps:

Avoid contact (including sexual contact) with anyone who is unwell or has an unusual rash.
Wash hands often with soap and water or an alcohol-based hand sanitiser containing at least 60% alcohol. Keep your hands away from your eyes, nose, and mouth. If you touch your face, make sure your hands are clean.
Talk to sexual partners about their sexual and general health and ask if they have any symptoms.
Before you have sex, go to a party or event, check yourself for mpox symptoms, including rashes and blisters. If you have mpox symptoms, take a break from attending events or having sex until you've been assessed by a health professional.
It can take up to three weeks for symptoms to appear after having contact with someone with mpox, so stay alert for symptoms after you have skin to skin or sexual contact with someone new.
Everyone is encouraged to exchange contact details with sexual partners, to help stop further mpox spread when cases occur.
Avoid touching items such as bedding/clothing and do not share eating utensils/cups, food or drink with anyone who has symptoms or has mpox.
Avoid contact with animals, especially rodents.
Do not eat, cook or prepare any type of raw or wild meat (bushmeat) or any meat from unknown sources.

Aid workers and health professionals planning humanitarian work in countries with outbreaks or isolated mpox cases should seek advice and training from their employer/organisation, before travel. Any organisation deploying UK resident staff to areas affected by mpox clade I virus, in response to the outbreak should register with the UKHSA Returning Workers Scheme (RWS).

Advice for people with HIV is available from the British HIV Association.

UK travellers experiencing symptoms abroad should:

Limit their contact with other people.
Get medical advice locally, calling ahead before going to a healthcare facility. If they are not able to call ahead, they should inform a staff member as soon as they arrive that they are concerned about mpox.
Check with a health professional that they are fit to travel.
Anyone diagnosed with mpox should not have sex while they have symptoms, including lesions, and must use condoms for 12 weeks after infection. This is to reduce the risk of spreading MPXV to partners.

Travellers should follow local public health advice. They may need to self-isolate, be admitted to hospital or put into a quarantine facility until they are no longer considered infectious to other people. Travel to an mpox affected area may affect travel health insurance options. Travellers should discuss their plans with their travel insurance company before they go.

Travellers who become unwell after returning to the UK should seek medical advice by telephone, see current NHS guidance.

More detailed information is available from the UKHSA mpox webpages.

Vaccine

The NHS previously offered a countrywide vaccination schedule to people most likely to be exposed to mpox. This included some healthcare workers, some men who are gay, bisexual or have sex with other men and people who had close contact with someone with mpox. This nationwide vaccine programme ended in July 2023.

Vaccination is still currently available in London and Greater Manchester for men who are gay, bisexual or have sex with other men, and who have multiple partners, participate in group sex or attend sex-on-premises venues; and staff who work at sex-on-premises venues.

Find an mpox vaccination site

For the current clade I outbreak vaccination indications for pre-exposure travel vaccination are being reviewed by the JCVI travel sub-committee, but vaccination is not currently recommended for travellers. Eligible groups for vaccination will be kept under review as information about the current outbreak emerges. Please refer to the Green Book - Immunisation against infectious disease for further information about vaccinations recommended prior to travel.

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