Mpox

Mpox is an infectious disease caused by the monkeypox 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 two different types of MPXV called clades: clade I (with subclades Ia and Ib) and clade II (with subclades IIa and IIb).

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 World Health Organization (WHO) in May 2023 following the global decline in clade II mpox cases.

Clade I mpox, which historically causes more severe illness than clade II infection had been reported in five central African countries prior to 2024. An outbreak caused by clade Ib mpox was reported in the DRC in 2023. 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. Sustained human-to-human transmission of clade Ib mpox continues in the DRC and many surrounding countries including Uganda and Burundi. As of March 2025, the mpox situation continues to meet the criteria of a PHEIC. Cases of clade I mpox detected outside the African Region have mainly been travel-related.

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 5 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 or semen/vaginal fluids of someone with mpox
• 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.

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

• Avoiding contact (including sexual contact) with anyone who is unwell or has an unusual rash.
• Washing hands often with soap and water or an alcohol-based hand sanitiser containing at least 60% alcohol. Avoiding touching the face (especially eyes, nose and mouth) unless hands are clean.
• Talking to sexual partners about their sexual and general health and asking about any symptoms.
• Checking for mpox symptoms, including rashes and blisters prior to having sex, going to a party or event. If symptoms are identified, travellers should seek medical advice locally and follow public health advice (see below).
• Staying alert for symptoms after having skin to skin or sexual contact with someone new. It can take up to three weeks for symptoms to appear after having contact with someone with mpox.
• Exchanging contact details with sexual partners, to help stop further mpox spread when cases occur.
• Avoiding touching items such as bedding/clothing or sharing eating utensils/cups, food or drink with anyone who has symptoms or has mpox.
• In areas where mpox is endemic, avoiding contact with animals, especially rodents. Travellers should 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.

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 during sex 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.

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.

Although the current risk from mpox remains low, a number of vaccination sites have opened across England for those at increased risk of getting the infection:

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

The UK does not currently recommend pre-travel vaccination for mpox. However, vaccination may be appropriate for certain specialist healthcare and humanitarian workers who go to affected countries to work within mpox response or sites with active outbreaks following a risk assessment. Eligible groups for vaccination will be kept under review as information about the current situation emerges. Please refer to the Green Book - Immunisation against infectious disease for further information about vaccinations recommended prior to travel.