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).
Epidemiological update
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.[6]
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.[7][8] 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.[9] 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.[10]
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.
WHO: 2022 monkeypox outbreak - global trends Opens in new window
Risk assessment
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.[6]
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.[6]
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.
Clinical presentation
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:[11]
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).[7]
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.
Transmission
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.[11] 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.[7]
This is a rapidly evolving situation and you should consult your local public health authority for current guidance.
Summary
Definition
History and exam
Key diagnostic factors
- rash/lesions (typical)
- rash/lesions (2022 outbreak)
- anorectal symptoms (2022 outbreak)
- fever
- lymphadenopathy
Other diagnostic factors
- headache
- backache
- myalgia
- pharyngitis/cough
- asthenia
- malaise
- nausea/vomiting
- diarrhoea
- delirium/confusion
- seizures
Risk factors
- recent travel to/living in endemic country or country with outbreak
- contact with suspected, probable, or confirmed case
- multiple sexual partners
- contact with infected animal
- children, pregnant women, immunocompromised
- HIV infection
- acute or chronic skin conditions
Diagnostic investigations
1st investigations to order
- polymerase chain reaction (PCR)
- FBC
- urea and electrolytes
- LFTs
- sexually transmitted infection tests
Treatment algorithm
Contributors
Authors
David L. Heymann, MD, DTM&H
Professor of Infectious Disease Epidemiology
London School of Hygiene and Tropical Medicine
University of London
Head
Centre on Global Health Security - Chatham House
London
UK
Disclosures
DLH declares that he has no competing interests.
Acknowledgements
Dr David L. Heymann would like to gratefully acknowledge Dr Tom Blanchard, the previous contributor to this topic.
Disclosures
TB is the principal investigator on an MRC/Wellcome/Newton Fund grant to make a Zika vaccine based on recombinant modified vaccinia Ankara.
Peer reviewers
Miguel G. Madariaga, MD, MSc, FACP
Infectious Diseases Consultant
Naples Community Hospital
Naples
FL
Disclosures
MGM declares that he has no competing interests.
Jimmy Whitworth, MD, FRCP
Professor of International Public Health
London School of Hygiene & Tropical Medicine
London
UK
Disclosures
JW declares that he has no competing interests.
Ashley Styczynski, MD, MPH
Epidemic Intelligence Service Officer
Poxvirus and Rabies Branch
Centers for Disease Control and Prevention
Atlanta
GA
Disclosures
AS declares that she has no competing interests.
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