Mpox outbreak in Africa: clade I mpox virus infection

Mpox outbreak continues to meet the WHO criteria of a public health emergency of international concern (PHEIC)

The third meeting of the WHO International Health Regulations (2005) Emergency Committee regarding the upsurge of mpox cases in 2024 met on 25 February 2025 [1]. The Committee agreed that the situation continued to meet the criteria of a public health emergency of international concern (PHEIC) initially declared in August 2024.

Background

Mpox is an infection caused by the monkeypox virus (MPXV). There are 2 distinct clades of the virus: clade I (with subclades Ia and Ib) and clade II (with subclades IIa and IIb). Historically, clade I mpox has been associated with a higher risk of people with the infection developing severe illness or dying, compared to clade II [2].

In May 2022, a global outbreak of clade II mpox emerged, mainly affecting gay, bisexual and other men who have sex with men [3].

Prior to 2024, clade I mpox had only been reported in 5 countries in central Africa [2]. The upsurge of clade I mpox in the Democratic Republic of Congo (DRC), which began in 2022 and subsequently spread to additional countries in 2024, marked the first known expansion of its geographical range.

Sustained human-to-human transmission of clade I mpox continues in the DRC and surrounding countries. As of 20 April 2025, a total of 26,503 confirmed cases of mpox had been reported from 24 countries within the previous 12 months. The majority of these cases were reported from DRC, Uganda and Burundi [4].

An overview of mpox epidemiology indicating where there may be a risk of clade I and clade II mpox exposure is available at GOV.UK – Mpox: affected countries.

The latest epidemiological data on mpox (all clades) can be found on the World Health Organization (WHO) mpox surveillance dashboard.

Cases of clade I mpox detected outside of the African Region have primarily been travel-related. While there is currently no evidence of sustained community transmission of clade I mpox outside of the African Region, limited local transmission (for example, household transmission) has been reported [5].

There have been no cases of clade Ia mpox in the UK, and only a small number of cases of clade Ib mpox. Most of these cases have appeared in travellers returning from affected areas in Africa or household contacts of a case. The risk to the UK population remains low although occasional imported cases are expected [6].

Data on confirmed cases of clade Ib mpox in the UK is available [7].

Please also check our Outbreak Surveillance database for updated information on recent outbreaks and mpox cases.

Mpox symptoms and management

Mpox can be transmitted when a person comes into close contact with an infected human, animal or contaminated material.

Person-to-person spread can occur through:

• touching the rash, skin lesions (spots, blisters or ulcers) or scabs of someone with mpox (including during sexual contact, kissing, cuddling or other skin-to-skin contact)
• contact with body fluids such as saliva, snot, mucus 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

There is a potential risk of mpox spreading through close and prolonged face-to-face contact (for example while talking, breathing, coughing or sneezing close to one another) with someone with mpox, however there is limited evidence for this..

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.

The incubation period (time from infection to first symptoms) is between 5 and 21 days. The first symptoms of mpox include:

• a high temperature
• a headache
• muscle aches
• backache
• swollen glands
• shivering (chills)
• exhaustion
• joint pain

A rash or pus-filled lesions then usually appear 1 to 5 days after the first symptoms. The rash (spots, blisters or ulcers) often begins on the face, then spreads to other parts of the body. This can include the mouth, genitals and anus. The number of sores can range from one to several thousand.

Most patients experience a mild self-limiting illness with spontaneous and complete recovery seen within 3 weeks of onset. However severe illness can occur and sometimes results in death. The risk of severe disease is higher in children, pregnant women and severely immunocompromised individuals (those with a weakened immune system).

Advice for travellers

Before you travel

Check Foreign Commonwealth and Development Office (FCDO) advice on whether it is advised to travel to your intended destination. This also includes information on entry requirements, safety and security.

Information is available on countries where mpox cases have been reported: GOV.UK: Mpox: affected countries. However, the situation may change rapidly in different countries, and travellers need to remain vigilant to the risk of mpox from nearby countries where cases have not been reported to date.

Check our Country Information pages for the latest guidance on vaccination, malaria and other health risks. Our Outbreak Surveillance database will provide information regarding recent outbreaks and mpox cases.

Before travelling to affected areas, you should:

• Check with a health professional that you are fit to travel. In particular, pregnant and immunosuppressed people are known to be at higher risk of severe infection.
• Check your travel health insurance before you go.
• Make sure you know the symptoms of mpox and how mpox is transmitted.

Vaccination

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.

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.

The JCVI continues to review latest data on the current situation and will continue to update vaccination recommendations accordingly.

Please refer to the Green Book - Immunisation against infectious disease for further information about mpox vaccine eligibility.

While you are away

Mpox can be spread through close contact of any kind, including through sexual and non-sexual contact.

The risk of mpox is low for most travellers. You can reduce your risk while travelling by taking sensible precautions to protect yourself from infection:

• 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 3 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.
• 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 mpox.
• If you are in areas where mpox is endemic, avoid contact with animals, especially rodents and do not eat, cook or prepare any type of raw or wild meat (bushmeat) or any meat from unknown sources.

If you are a UK traveller and you are experiencing symptoms abroad, you should:

• Limit your contact with other people.
• Get medical advice locally, calling ahead before going to a healthcare facility. If you are not able to call ahead, inform a staff member as soon as you arrive that you are concerned about mpox.
• Check with a health professional that you are fit to travel.
• If you are diagnosed with mpox, you should not have sex until your symptoms fully resolve, and should use a condom during sex for 12 weeks after infection. This is to reduce the risk of spreading MPXV to partners.

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

For more information on the risk of mpox and sex, please see the WHO public health advice for gay, bisexual and other men who have sex with men.

For advice for people living with HIV, see the British HIV Association (BHIVA) statement on mpox virus.

When you return

If you have just arrived at a UK airport or port of entry having recently travelled to any of the countries affected by mpox, and have any new spots, blisters or ulcers, you should speak to a member of port or border staff to get advice.

If you have visited one of the affected countries and develop symptoms within 21 days of returning to the UK, please isolate at home and call NHS 111 for advice, letting them know your travel history.

See current advice on the NHS mpox page.

Advice for health professionals

Health professionals who suspect a case of mpox should follow the Mpox: guidance on when to suspect a case of mpox. Guidance is available on diagnostic testing, contact tracing and de-isolation and discharge of cases.