Mpox

Mpox, previously called ‘monkeypox’, is a rare disease caused by an infection from the monkeypox virus. The virus was originally found in captive monkeys in Denmark in 1958, before being found in humans in 1970 in the equatorial province of the Democratic Republic of Congo (DRC), Central Africa.

According to the World Health Organization, cases are most commonly found in East, West, or Central Africa. On the 14th August 2024, the WHO declared a mpox outbreak in the Democratic Republic of the Congo as a Public Health Emergency of International Concern (PHEIC). This is where a public health emergency, e.g. the international spread of disease, could potentially require a coordinated international response. The WHO is concerned that the new clade (type) of mpox is spreading more rapidly, and cases have been reported in other countries in Africa.

The WHO have started a process to speed up the approval of mpox vaccines for emergency use. This will make it easier for lower-income countries, which haven't approved the vaccines yet, to get access to them. The emergency approval also allows organisations like Gavi and UNICEF to buy and distribute these vaccines more quickly. Previously,in May 2022, cases broke out globally with 117 countries reporting over 97 thousand cases and 186 deaths (June 2024).

The outbreak primarily affected men who are gay, bisexual, or have sex with other men, but it is important to note that anyone who is not immune can catch and spread mpox. The risk of severe disease is higher in young children, pregnant women, people with eczema, and immunosuppressed individuals. Mpox is similar to smallpox – a disease we haven’t seen since 1977 because of the success of the smallpox vaccination programme; because of these similarities, the smallpox vaccine, MVA-BN (or IMVANEX), can protect against mpox. Two doses are needed for the best protection.

This vaccine was offered to people who are at the highest risk of catching mpox during the outbreak, but this ended nationally in July 2023 in the UK.  See the mpox vaccine page for more information. Globally, two other vaccines are recommended by the WHO – LC16 and ACAM2000 are appropriate for use. However, these aren’t recommended for some people, such as those who are immunocompromised.

Mpox - here's what you need to know

The symptoms of mpox may begin within a week, but can start up to three weeks after exposure, typically lasting 2–4 weeks.  Symptoms may last longer in someone with a weakened immune system. 

Common symptoms of mpox are:

• rash
• fever
• sore throat, cough, blocked nose
• headache
• muscle aches
• back pain
• low energy
• swollen lymph nodes (bean-shaped glands throughout the body)

The rash begins as a flat sore which develops into a round, tense blister, which may be itchy or painful and is often discoloured in the centre. As the rash heals, the lesions dry up, crust over and fall off. Some people have lots of sores, while others may only have a few. These can appear anywhere on the body and are often seen at the site of initial infection.

Globally, between January 2022 and 31 March 2024, there have been 95,226 confirmed cases of mpox, and 185 confirmed deaths.  In Europe, there were 27,179 confirmed cases and 10 deaths.  The majority of the documented deaths from mpox have been in The Americas.

Mpox spreads through direct contact with infectious skin or other lesions such as in the mouth or on the genitals.

Direct contact includes:

• face-to-face
• skin-to-skin
• mouth-to-mouth
• mouth-to-skin contact
• Respiratory droplets or short-range aerosols from prolonged close contact 

Mpox can spread to other members of the household and sex partners. People with multiple sexual partners are at higher risk.

Animal-to-human transmission of mpox occurs from infected animals to humans from bites or scratches, or during activities such as hunting, cooking, and eating animals. It is unknown what the animal reservoir (where the virus naturally lives, grows, and multiplies) is for mpox, although mammals such as monkeys and squirrels can get infected.

People can also catch mpox from contaminated objects such as clothing or bedding. It can also be caught from a contaminated needle such as through sharps injuries in health care, and has been described as appearing directly on a new tattoo.

There is no specific treatment for mpox and patients are recommended supportive care, either at home if they are relatively well or in hospital if they are unwell. It is important that someone with a confirmed case of mpox avoids spreading it to others whilst they are infectious.

Mpox is very similar to smallpox – a virus we haven’t seen since 1977 because of the success of the vaccination programme; because of these similarities, the smallpox vaccine, modified vaccinia Ankara-Bavarian Nordic, also known as MVA-BN or IMVANEX, can protect against mpox. Two doses are needed for the best protection.

The NHS mpox outbreak vaccination programme is currently only 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. Some staff who work in specialist roles, such as caring for patients with mpox, or staff who work at sex-on-premises venues may also be eligible.

Vaccination may also be offered up to 14 days after exposure to the virus to reduce the symptoms of the disease for those who do not already have symptoms. This may be considered in those at higher risk of serious monkeypox infection (children under five years of age, the immunosuppressed and pregnant women).

See the mpox vaccine page for more information.

Types of mpox

There are two types of mpox called clades; one is found mostly in Central Africa (Clade I), and the other in West Africa (Clade II). Clade I viruses cause more severe symptoms and up to 10% of people who catch this version unfortunately die. Although Clade II is less severe, it can cause death.  It is divided into two subclades; clade IIb is responsible for the 2022-2024 global outbreak. As of April 2023 the number of people who had died from this outbreak was 186, <1% of all the confirmed cases (https://worldhealthorg.shinyapps.io/mpx_global/)

Mpox outbreak in DRC

On the 14th August 2024, the WHO announced a mpox outbreak in the Democratic Republic of the Congo (DRC) which is categorised as a public health emergency of international concern (PHEIC). This announcement followed recommendations from independent experts.  There are concerns that the rise in cases of a new type of mpox (clade 1b) could lead to the disease spreading across different African countries and possibly even to other parts of the world.

Mpox has been reported in the DRC for over a decade, with cases increasing each year. Last year, cases rose sharply, and this year, more than 15,600 cases and 537 deaths have already been reported, surpassing last year's total. A new virus strain, clade 1b, emerged last year in the DRC and is spreading rapidly. It is thought to be spreading mainly through sexual networks.

In the past month, over 100 confirmed cases of clade 1b have been reported in four neighbouring countries—Burundi, Kenya, Rwanda, and Uganda—that had not previously reported mpox. Experts believe the actual number of cases is likely higher since many suspected cases have not been tested.

The WHO explain a coordinated international response will be needed to stop the spread of mpox. The Emergency Use Listing process to speed up the approval of mpox vaccines for emergency use has been triggered. This will make it easier for lower-income countries, which haven't approved the vaccines yet, to get access to them. The emergency approval also allows organisations like Gavi and UNICEF to buy and distribute these vaccines more quickly.

Mpox outbreak in the UK  

Between 2018 and 2022, the UK had only a few cases of mpox, all were Clade II and originated from West Africa. The spread was effectively contained through quick diagnosis, isolation, and care at designated centres. Close contacts were quarantined and monitored, and post-exposure vaccination was recommended to prevent serious symptoms.

However, in April/May 2022, three separate cases of mpox were identified. The first case involved an imported case from Nigeria but this didn't lead to further transmission. The second case suggested local transmission (caught within the UK), with an initial case having no travel history infecting two household members.

The third incident seemed to indicate transmission primarily among gay, bisexual, and other men who have sex with men. By September 2022, over 3,500 confirmed cases had been reported, predominantly in London, with the majority affecting males. The outbreak shows connections to similar cases globally, including in Canada, Portugal, Belgium, and Germany.

Source: Our World in Data