Multi-country monkeypox outbreak (2022)
There is currently an outbreak across several countries with community transmission, multiple generations of spread, and new modes of transmission.
Outside of the African region, the outbreak is predominantly affecting gay, bisexual, and other men who have sex with men (MSM) who have reported recent sex with one or multiple male partners. However, it can affect anyone. Currently, there is no signal of sustained transmission beyond these networks, although cases have been reported rarely in women (including pregnant women) and children.
Epidemiological investigations are ongoing, but the majority of reported cases so far have no established travel links to countries where the virus was historically known to be present. This is the first time that local transmission has been reported in newly-affected countries without epidemiological links to countries that have previously reported cases (i.e., West or Central Africa).
Globally, over 65,000 confirmed cases have been reported from 106 countries/territories/areas between 1 January 2022 and 30 September 2022, according to the World Health Organization (WHO). The overall number of cases has been declining in recent weeks, likely due to behavioural modifications and vaccination, among other factors.
Ten countries account for 86.7% of the cases reported globally. The ten most affected countries (in order of highest to lowest case numbers) are: US, Brazil, Spain, France, UK, Germany, Peru, Colombia, Mexico, and Canada. Thirty-three countries have reported no new cases for over 21 days.
Of cases with information available, 97.5% were in males with a median age of 35 years (range 29 to 42 years), 89.3% identified as MSM, and 47.2% of cases were HIV-positive. Males aged 18 to 44 years are disproportionately affected, and account for 78.9% of cases. A sexual encounter was the reported mode of transmission in 87.1% of all reported transmission events. The majority of cases in women are in heterosexual women infected via sexual transmission. A small number of cases have been reported in pregnant women. Most cases in children are reported from the region of the Americas.
Demographics of cases in Africa are similar to recent previous outbreaks there, but significantly different from other regions (64.5% of cases are in males with a median age of 25 years).
Twenty-seven deaths have been reported (16 in Africa, three in Spain, one in Belgium, one in the Czech Republic, one in India, two in Brazil, one in Ecuador, one in Cuba, one in the US). Whether mortality is associated with any specific factors is currently unknown.
In the UK, 3485 confirmed cases were reported as of 26 September 2022. There has been an overall decline in the number of new cases identified in the last few weeks, and activity appears to have peaked in July.
Of cases with information available, 99% were male, the median age was 36 years, 96.8% identified as MSM, 52.7% had a history of a sexually transmitted infection in the last year, and 25.9% were HIV-positive.
There have been no reported deaths in the UK.
In the US, 25,851 cases were reported as of 30 September 2022. There has been an overall decline in the number of new cases identified in the last few weeks, and activity appears to have peaked in August.
Of cases with information available, 99.1% were male, the median age was 35 years, and 99% identified as MSM. There have been 29 cases reported in children.
There has been one death reported in the US, and several others are being investigated.
The WHO has determined that the outbreak constitutes a Public Health Emergency of International Concern (PHEIC) at its meeting of the International Health Regulations (2005) Emergency Committee, held on 21 July 2022. The agency has issued a set of temporary recommendations for member states to help bring the outbreak under control.
The WHO has assessed the overall public health risk at a global level as moderate. In the European region and region of the Americas, the risk is considered to be high.
The extent of local transmission is unclear at this stage, but the sudden appearance of cases simultaneously in several countries suggests that there may have been undetected transmission for some time.
The clinical presentation of cases associated with this outbreak has been atypical, with many cases not presenting with the classically described clinical picture. Lesions tend to be localised to the genital, perineal/perianal, or perioral areas and often do not spread further. Many patients have no symptoms at all.
Other atypical presentations associated with this outbreak include:
Presentation of only a few lesions (or even just a single lesion) and may not be disseminated
Absence of skin lesions with anal pain and bleeding
Lesions appearing at different stages of development (asynchronous)
Rash does not always appear on palms and soles
Appearance of lesions before the prodromal period.
Approximately 10% of cases require hospital admission for symptom control or management of complications (this includes patients who cannot isolate at home).
Nearly all patients with perianal or rectal lesions have reported pain, and hospital admission has been required for patients with severe rectal pain and proctitis.
Oropharyngeal symptoms may cause pain or difficulty swallowing (odynophagia).
Lesions on the external genitalia have caused severe swelling and pain, and in some cases the development of paraphimosis.
Secondary bacterial infections of skin and soft tissues (cellulitis) may also occur.
The group of variants largely circulating in the 2022 global outbreak belong to the Clade IIb variant of the monkeypox virus.
The modes of transmission during sexual contact remain unknown. It is known that close physical contact can lead to transmission, but it is not yet clear what role sexual bodily fluids play in transmission, if any. The extent to which pre-symptomatic or asymptomatic infection may occur is unknown. Limited household transmission has been reported. No confirmed cases of airborne transmission have been reported. There are a small number of cases with no identified route of acquisition.
This is a rapidly evolving situation and you should consult your local public health authority for current guidance.
Monkeypox is endemic in West and Central Africa. However, travel-associated cases have been sporadically reported in the UK, the US, Singapore, and Israel over the years. An ongoing outbreak in several countries with no direct travel links to an endemic area and an atypical presentation is currently being investigated.
All suspected cases should be isolated immediately and the regional infectious diseases unit notified. Cases should be managed by experts, including public health officials, to prevent a potential emergency situation.
Patients typically present with a characteristic rash that progresses in sequential stages at the same stage of development over all affected areas of the body. It may be associated with fever, lymphadenopathy, backache, and myalgia. However, the clinical presentation in the current ongoing multi-country outbreak may be atypical.
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 to 4 weeks. However, serious illness with severe complications can occur, particularly in children, pregnant women, and immunocompromised people. The case fatality rate varies depending on the virus clade, geographical location, and availability of medical facilities.
Vaccines are available for pre- and post-exposure vaccination.
A viral zoonotic disease caused by the monkeypox virus. The virus can be transmitted to humans from different wild animals, such as non-human primates and rodents, although its natural host reservoir is unknown. While animal-to-human transmission is the more common mode of transmission, human-to-human transmission does occur and has led to small, but contained, human outbreaks in the past. However, there is currently an ongoing global outbreak involving human-to-human transmission. The virus is a hazard group 3 pathogen.
The name of the disease and the virus is currently under review by the World Health Organization and the International Committee on the Taxonomy of Viruses.
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