Open Outbreak

Mpox

Also known as: monkeypox, MPXV, clade I, clade II

Mpox is a viral disease caused by monkeypox virus, an orthopoxvirus related to the virus that caused smallpox. It can spread from person to person through close contact, including direct skin contact, sexual contact, mouth-to-mouth contact, face-to-face exposure at close range, contaminated bedding or clothing, and from infected animals. Symptoms usually start 1–21 days after exposure and often include a rash or sores, fever, swollen lymph nodes, headache, muscle aches and low energy. Many people recover in 2–4 weeks, but severe illness can happen, especially in children, pregnant people, and people with weak immune systems. WHO says vaccines for mpox exist, but vaccination is only one part of control. Treatment is mainly supportive care such as pain relief, fluids, skin care and treatment of complications; some antiviral drugs have activity against mpox, but the evidence base is still developing. Clade IIb drove the 2022–2023 global outbreak, while clades Ia and Ib have caused growing concern in parts of Africa and beyond.

Key facts

TransmissionClose contact with a person with mpox, contaminated materials, or infected animals; this includes skin-to-skin and sexual contact, mouth-to-mouth or mouth-to-skin contact, close face-to-face exposure, and spread during pregnancy, birth or after birth.
IncubationUsually within 1 week; can range from 1 to 21 days after exposure.
Case fatalityUnknown overall. WHO states mpox can be fatal in some cases. In one 2024 South Africa outbreak, 3 deaths occurred among 20 confirmed cases (15%), but this should not be treated as a general rate.
Reproduction numberunknown
VaccineVaccines for mpox exist. WHO says vaccination should be considered along with other public health measures.
TreatmentMainly supportive care. WHO recommends pain and fever control, hydration, nutrition, skin care, prevention of secondary infection, and treatment of co-infections. Reviews note antiviral activity for tecovirimat, cidofovir and brincidofovir, but evidence is still being assessed.
ReservoirUnknown. WHO says the natural animal reservoir is not known, although various small mammals are susceptible.
Endemic regionsHistorically endemic in parts of West, Central and East Africa; WHO reported endemic areas especially in the Democratic Republic of the Congo, with wider international spread since 2022.

Transmission

Mpox spreads mainly through close contact. WHO says this includes direct skin-to-skin contact, including sex, as well as mouth-to-mouth or mouth-to-skin contact such as kissing. It can also spread during close face-to-face contact when infectious respiratory particles are generated at short range. People may also catch it from contaminated objects like bedding, clothing, or other materials that touched lesions. In health care, needle injuries are another possible route. Animal-to-human spread can happen through bites, scratches, or contact during hunting, skinning, trapping, cooking, or handling carcasses. During pregnancy, birth, or soon after birth, the virus can also pass to the baby. WHO notes that more research is still needed on how transmission differs by setting and outbreak. The natural reservoir remains unknown, which adds uncertainty when trying to predict where spillover from animals may happen.

Symptoms and severity

Mpox often causes a rash or sores together with fever, swollen lymph nodes, headache, muscle aches, back pain and low energy. WHO says symptoms usually begin within a week of exposure, but can start as late as 21 days after exposure, and they typically last 2–4 weeks. The rash may start on the face, hands or feet, but it can also begin on the genitals or other sites of contact. Some people have only a few lesions, while others have many. Severe complications can include bacterial skin infection, pneumonia, eye infection with possible vision loss, dehydration, malnutrition, sepsis, encephalitis, myocarditis, proctitis and urinary problems. WHO says children, pregnant people and people with weak immune systems are at higher risk of serious disease and death. Mpox can be fatal, but the overall case-fatality rate is not fixed and varies by outbreak, clade, access to care and who is affected.

Treatment and vaccines

Treatment is mainly supportive. WHO recommends treating pain and fever, maintaining fluids and nutrition, caring for the skin and sores, preventing secondary bacterial infection, and managing co-infections such as HIV when present. That matters because dehydration, pain, and infected lesions can make the illness much worse even when there is no single “cure.” WHO also says vaccines for mpox exist and that vaccination should be used alongside other public-health measures rather than as the only response. Reviews in the medical literature describe three antiviral drugs with activity against mpox and related orthopoxviruses: tecovirimat, cidofovir and brincidofovir. But those reviews do not show that every patient needs antiviral treatment, and the evidence for clear clinical benefit is still being worked out. In plain terms, vaccines and antivirals are tools, but early diagnosis, symptom care, infection control and access to routine medical care still do much of the work.

Where it occurs

Mpox has long been described as endemic in parts of West, Central and East Africa. WHO says it is especially established in the Democratic Republic of the Congo, where multiple provinces have reported cases and the geographic range has expanded in recent years. The 2022–2023 global outbreak changed the map sharply: clade IIb spread widely in countries that had not previously reported sustained community transmission. WHO’s fact sheet says that outbreak continues, including in some African countries. At the same time, clades Ia and Ib have caused growing outbreaks in the Democratic Republic of the Congo and other African countries, and clade Ib has been detected outside Africa as well. The animal reservoir is still unknown, so the full ecological range is not clear. For a general reader, the important point is that mpox is no longer only a problem of a few forested areas; travel-linked cases and local transmission have both been documented in several regions.

Recent history

This site’s archive lists 20 WHO notices or major outbreak records for mpox since 1996, which shows repeated reappearance rather than a one-off event. Older WHO items document outbreaks in the Democratic Republic of the Congo and changes in the pattern of human infection in 1997. Reports then appear from Central African Republic, Nigeria, Cameroon, Singapore, the United Kingdom and the United States before the much larger 2022 multi-country outbreak. WHO later described the 2022–2023 event as a global outbreak with about 87,000 cases and 140 deaths in the site archive record. In 2024, WHO reported an expanding mpox situation in the African Region, a growing clade Ib outbreak linked to the Democratic Republic of the Congo, and the first reported clade Ib case outside the African Region in Sweden. In 2025, WHO warned of broader clade Ib transmission, and in 2026 it reported recombinant viruses with genomic elements from clades Ib and IIb.

What to watch

Several changes would make mpox more concerning. One is spread into new countries or sustained community transmission in places that previously saw only travel-related cases. WHO highlighted this risk when clade Ib was reported outside Africa and later in all WHO regions. Another warning sign is clearer evidence of efficient human-to-human transmission in settings beyond the sexual networks that drove much of the 2022 global outbreak, especially if transmission becomes harder to interrupt. A rise in severe disease in children, pregnant people, or people with weak immune systems would also matter. Watch for signs that the virus is changing in ways that affect spread or severity, including recombinant strains such as the clade Ib/IIb viruses reported by WHO in 2026. Finally, shortages or uneven access to vaccines, diagnostics and supportive care would raise risk, as would reduced effectiveness of available antivirals or other clinical tools.

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