Mpox (monkeypox)
Global mpox outbreak
There is currently an ongoing global outbreak across several countries with community transmission, multiple generations of spread, and new modes of transmission, which started in May 2022. The World Health Organization (WHO) declared that the outbreak constitutes a Public Health Emergency of International Concern (PHEIC) in July 2022. The public health emergency expired in the US on 31 January 2023. There may have been undetected transmission for some time prior to the outbreak.
Globally, over 84,000 confirmed cases and 81 deaths were from 110 countries/territories/areas between 1 January 2022 and 20 January 2023.[7] The number of cases peaked in August 2022 and has since been steadily declining, likely due to behavioural modifications and vaccination, among other factors.
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 mpox. 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 epidemiological links to countries that have previously reported cases (i.e., West or Central Africa). The group of variants largely circulating in the outbreak belong to the Clade IIb variant of the monkeypox virus.
The clinical presentation has been atypical. Lesions tend to be localised 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.
Summary
Definition
History and exam
Key diagnostic factors
- rash/lesion(s)
- anorectal symptoms
- fever
- lymphadenopathy
Other diagnostic factors
- fatigue/asthenia/malaise
- myalgia
- headache
- sore throat
- backache
- cough
- 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
- random one-time sexual encounters or multiple sexual partners
- recent tattoo or piercing
- contact with infected animal
- children (severe disease)
- pregnant women (severe disease)
- immunocompromised (severe disease)
- HIV infection (severe disease)
- acute or chronic skin conditions (severe disease)
- sexually transmitted infection
Diagnostic investigations
1st investigations to order
- polymerase chain reaction (PCR)
- FBC
- 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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