Last reviewed: 28 Oct 2022
Last updated: 22 Nov 2022
22 Nov 2022

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.[6]

  • 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.

See Epidemiology

Original source of update

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
  • diarrhea
  • delirium/confusion
  • seizures

Risk factors

  • 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)

Diagnostic investigations

1st investigations to order

  • polymerase chain reaction (PCR)
  • CBC
  • urea and electrolytes
  • LFTs
  • sexually transmitted infection tests

Investigations to consider

  • CT abdomen/pelvis
  • serology
  • blood culture
  • malaria antigen test

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, FFPH, FMedSci, DTM&H

Emeritus Professor

London School of Hygiene & Tropical Medicine

London

UK

Disclosures

JW declares that he has no competing interests.

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