Multi-country monkeypox outbreak
There is currently an ongoing outbreak across several countries with community transmission, multiple generations of spread, and new modes of transmission. The World Health Organization (WHO) has determined that the outbreak constitutes a Public Health Emergency of International Concern (PHEIC). There may have been undetected transmission for some time prior to the outbreak.
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. The modes of transmission during sexual contact remain unclear, but available evidence indicates that the principal mode is through close contact with skin or mucosal lesions during sexual activity with a person with monkeypox. Currently, there is no signal of sustained transmission beyond these networks, although cases have been reported rarely in women and children.
The majority of reported cases 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 epidemiologic links to countries that have previously reported cases (i.e., West or Central Africa). The group of variants largely circulating in the 2022 global outbreak belong to the Clade IIb variant of the monkeypox virus.
The clinical presentation has been atypical. Lesions tend to be localized to the genital, perineal/perianal, or perioral areas and often do not spread further. There may only be a few lesions, a single lesion, or no visible lesions. Lesions may be at different stages of development, and may appear before prodromal symptoms. Proctitis may be the only presenting symptom in some patients. While the majority of cases are mild, a small number of patients require hospital admission for symptom control or management of complications.
Globally, over 80,000 confirmed cases and 52 deaths have been reported from 110 countries/territories/areas between 1 January 2022 and 17 November 2022, according to the WHO. The overall number of cases has been declining, likely due to behavioral modifications and vaccination, among other factors.
Ten countries account for 86% of the cases reported globally. The ten most affected countries (in order of highest to lowest case numbers) are: US, Brazil, Spain, France, Colombia, UK, Germany, Peru, Mexico, and Canada.
Of cases with information available, 97% were in males with a median age of 34 years (range 29 to 41 years), 86% identified as MSM, and 50% of cases were HIV-positive. Males ages 18 to 44 years are disproportionately affected, and account for 80% of cases. A sexual encounter was the reported mode of transmission in 72% of all reported transmission events (most commonly in a party setting with sexual contacts). 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 (65% of cases are in males with a median age of 25 years).
Current information on the epidemiology of this outbreak is available from public health authorities.
Monkeypox was historically known to be endemic in West and Central Africa. However, an atypical outbreak is currently ongoing in many countries.
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.
Historically, patients presented with a characteristic rash that progressed in sequential stages at the same stage of development. However, the rash in the current outbreak is 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.
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.
Vaccines are available for pre- and postexposure vaccination.
A viral zoonotic disease caused by the monkeypox virus. The virus can be transmitted to humans from different wild animals, such as nonhuman 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.
History and exam
- recent travel to/living in endemic country or country with outbreak
- contact with suspected, probable, or confirmed case
- random one-time sexual encounters or multiple sexual partners
- recent tattoo or piercing
- contact with infected animal
- children, pregnant women, immunocompromised (severe disease)
- HIV infection (severe disease)
- acute or chronic skin conditions (severe disease)
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