Mpox (monkeypox) is an infectious disease caused by the monkeypox virus. It can cause a painful rash, enlarged lymph nodes and fever. Most people fully recover, but some get very sick.

Anyone can get mpox. It spreads from contact with infected:

persons, through touch, kissing, or sex,animals, when hunting, skinning, or cooking them, materials, such as contaminated sheets, clothes or needles, pregnant persons, who may pass the virus on to their unborn baby.

The disease mpox (formerly monkeypox) is caused by the monkeypox virus (commonly abbreviated as MPXV), an enveloped double-stranded DNA virus of the Orthopoxvirus genus in the Poxviridae family, which includes variola, cowpox, vaccinia and other viruses. The two genetic clades of the virus are clades I and II.

The monkeypox virus was discovered in Denmark (1958) in monkeys kept for research and the first reported human case of mpox was a nine-month-old boy in the Democratic Republic of the Congo (DRC, 1970). Mpox can spread from person to person or occasionally from animals to people. Following eradication of smallpox in 1980 and the end of smallpox vaccination worldwide, mpox steadily emerged in central, east and west Africa. A global outbreak occurred in 2022–2023. The natural reservoir of the virus is unknown – various small mammals such as squirrels and monkeys are susceptible.

Transmission

Person-to-person transmission of mpox can occur through direct contact with infectious skin or other lesions such as in the mouth or on genitals; this includes contact which is

face-to-face (talking or breathing), skin-to-skin (touching or vaginal/anal sex), mouth-to-mouth (kissing), mouth-to-skin contact (oral sex or kissing the skin), respiratory droplets or short-range aerosols from prolonged close contact

The virus then enters the body through broken skin, mucosal surfaces (e g oral, pharyngeal, ocular, genital, anorectal), or via the respiratory tract. Mpox can spread to other members of the household and to 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, skinning, trapping, cooking, playing with carcasses, or eating animals. The extent of viral circulation in animal populations is not entirely known and further studies are underway.

People can contract mpox from contaminated objects such as clothing or linens, through sharps injuries in health care, or in community setting such as tattoo parlours.

Signs and symptoms

Mpox causes signs and symptoms which usually begin within a week but can start 1–21 days after exposure. Symptoms typically last 2–4 weeks but may last longer in someone with a weakened immune system.

Common symptoms of mpox are:

rash, fever, sore throat, headache, muscle aches

back pain

low energy

swollen lymph nodes.

For some people, the first symptom of mpox is a rash, while others may have different symptoms first.

The rash begins as a flat sore which develops into a blister filled with liquid and may be itchy or painful. As the rash heals, the lesions dry up, crust over and fall off.

Some people may have one or a few skin lesions and others have hundreds or more. These can appear  anywhere on the body such as the:

palms of hands and soles of feet

face, mouth and throat

groin and genital areas

anus.

Some people also have painful swelling of their rectum or pain and difficulty when peeing.

People with mpox are infectious and can pass the disease on to others until all sores have healed and a new layer of skin has formed.

Children, pregnant people and people with weak immune systems are at risk for complications from mpox.

Typically for mpox, fever, muscle aches and sore throat appear first. The mpox rash begins on the face and spreads over the body, extending to the palms of the hands and soles of the feet and evolves over 2-4 weeks in stages – macules, papules, vesicles, pustules. Lesions dip in the centre before crusting over. Scabs then fall off. Lymphadenopathy (swollen lymph nodes) is a classic feature of mpox. Some people can be infected without developing any symptoms.

Diagnosis

Identifying mpox can be difficult as other infections and conditions can look similar. It is important to distinguish mpox from chickenpox, measles, bacterial skin infections, scabies, herpes, syphilis, other sexually transmissible infections, and medication-associated allergies. Someone with mpox may also have another sexually transmissible infection such as herpes. Alternatively, a child with suspected mpox may also have chickenpox. For these reasons, testing is key for people to get treatment as early as possible and prevent further spread.

Detection of viral DNA by polymerase chain reaction (PCR) is the preferred laboratory test for mpox. The best diagnostic specimens are taken directly from the rash – skin, fluid or crusts – collected by vigorous swabbing. In the absence of skin lesions, testing can be done on oropharyngeal, anal or rectal swabs. Testing blood is not recommended. Antibody detection methods may not be useful as they do not distinguish between different orthopoxviruses.

Treatment and vaccination

The goal of treating mpox is to take care of the rash, manage pain and prevent complications. Early and supportive care is important to help manage symptoms and avoid further problems.

Getting an mpox vaccine can help prevent infection. The vaccine should be given within 4 days of contact with someone who has mpox (or within up to 14 days if there are no symptoms).

Self-care and prevention

Most people with mpox will recover within 2–4 weeks. Things to do to help the symptoms and prevent infecting others:

 Source – WHO https://www.who.int/news-room/fact-sheets/detail/monkeypox