Mpox

Mpox was historically known to be endemic in West and Central Africa. However, the epidemiology and clinical course has changed in recent outbreaks compared with previous outbreaks.

Historically, patients presented with a characteristic rash that progressed in sequential stages at the same stage of development. However, in more recent outbreaks, the rash has been atypical, with lesions generally localized to the genital, perineal/perianal, or perioral areas. Lesions may be few and at different stages of development. Symptoms such as fever, lymphadenopathy, headache, backache, and myalgia may appear before or after the rash, or not at all.

Many other conditions present in a similar way, so it is important to keep in mind possible differentials as these are far more likely to be the cause.

Usually a self-limiting illness with most patients recovering within 2-4 weeks. However, serious illness with severe complications can occur, particularly in children, pregnant women, and immunocompromised people. Supportive care and consideration of antiviral therapy are the mainstay of management.

Vaccines are available for pre- and postexposure vaccination.

Mpox is a viral zoonotic disease caused by the monkeypox virus (MPXV).[1]World Health Organization. Clinical management and infection prevention and control for mpox: living guideline, May 2025. Jun 2025 [internet publication]. https://www.who.int/publications/i/item/B09434  There are two distinct clades of the virus: clade I (consisting of subclades Ia and Ib) and clade II (consisting of subclades IIa and IIb). The clinical presentation is typically the same, regardless of the clade. The virus can be transmitted to humans from different wild animals, such as nonhuman primates, rodents, antelopes and gazelles, and tree squirrels, although its natural host reservoir is unknown. While animal-to-human transmission was the more common mode of transmission in endemic countries, human-to-human transmission does occur and there has been an increasing number of human outbreaks in recent years. The virus is a hazard group 3 pathogen.[2]Health and Safety Executive, Advisory Committee on Dangerous Pathogens. The approved list of biological agents. July 2021 [internet publication]. https://www.hseni.gov.uk/publications/misc-208-fourth-edition-approved-list-biological-agents

Mpox was formerly known as monkeypox. The World Health Organization (WHO) began using mpox as a synonym for monkeypox from November 2022, and this name has been adopted globally by most countries.​[3]World Health Organization. WHO recommends new name for monkeypox disease. Nov 2022 [internet publication]. https://www.who.int/news/item/28-11-2022-who-recommends-new-name-for-monkeypox-disease ​ The Centers for Disease Control and Prevention (CDC) was using the term mpox until September 2025, when they reverted back to using the term monkeypox. This topic uses the term mpox.