WHO reaffirms mpox outbreak in Africa still meets criteria for a public health emergency of international concern
The World Health Organization (WHO) declared the current mpox outbreak in Africa a public health emergency of international concern (PHEIC) on the 14th August 2024, and this was reaffirmed on 27 February 2025. PHEIC status aims to accelerate funding, research, and international public health measures and cooperation to contain a disease, and is the WHO’s highest level of alert possible.
The PHEIC has been declared due to the following reasons:
An upsurge of mpox cases in parts of Africa
Emergence of a new variant of mpox, known as clade Ib, which appears to be spread mainly by sexual transmission
Rapid spread of the clade Ib variant in the Eastern Democratic Republic of the Congo (DRC) and reports of cases in several neighboring countries (e.g., Burundi, Kenya, Rwanda, Uganda)
Potential to spread further across other countries in Africa, and possibly outside of Africa
In the past 12 months, over 23,000 laboratory-confirmed cases of mpox have been reported in Africa, including 98 deaths (as of 30 March 2025). The three countries with the majority of cases are the DRC, Uganda, and Burundi.[12]
Although the epidemiology is not fully understood, the current spread of mpox in Africa is attributed to two distinct ongoing outbreaks in the DRC:
A clade Ia outbreak primarily in mpox-endemic areas mainly affecting children.
A clade Ib outbreak in the eastern part of the country that has been rapidly spreading and reaching neighboring countries that have not previously reported mpox cases. The outbreak is affecting both children and adults, and is spreading rapidly among adults through close contact including sexual contact identified within networks of sex workers and their clients.
Travel-related cases of clade Ib mpox have now also been reported in countries outside of Africa including India, Sweden, Thailand, Germany, the US, the UK, Belgium, Canada, and France.
Situation in the UK
The first case of clade Ib mpox detected in the UK was reported on 30 October 2024. As of 10 February 2025, nine confirmed cases of clade Ib mpox had been reported in the UK. Most cases had a travel history to Uganda. However, three cases were detected in household contacts of the first case (who had recently traveled to countries in Africa currently experiencing mpox outbreaks).[25]
A single confirmed case with no reported travel history and no reported link with a previously confirmed case was reported in the UK in early April 2025. All contacts were followed up and no further cases were identified. Investigations into the source of the infection are ongoing.[26]
The wider risk to the UK general population remains low.
Both clades of mpox (clade I and clade II) are no longer classified as a high consequence infectious disease (HCID) in the UK, as of March 2025.[27]
Situation in the US
The first case of clade Ib mpox detected in the US was reported on 16 November 2024. The infection was diagnosed in a person in California who recently traveled to the US from Eastern Africa.[28]
Three more cases have been reported since then (as of 1 April 2025). All cases were in people who had recently traveled to affected areas in Central and Eastern Africa, and the cases were not linked.[29]
The wider risk to the US general population remains low.
It is unclear at this time whether disease caused by the clade Ib variant differs from that of the clade II variant that caused the ongoing 2022 global outbreak, or whether current vaccines are effective against the new variant. However, the clinical presentation of clade Ib mpox appears to be similar to the signs and symptoms reported in the global clade II mpox outbreak, and differs from clade I outbreaks elsewhere in Africa.
Updated information on the situation is available from public health authorities.
This is the second time the WHO has declared an mpox outbreak to be a PHEIC, with the first one declared in July 2022 due to a global outbreak in countries that had not previously experienced cases. This outbreak was due to the clade IIb variant. The emergency was declared over in May 2023 as the number of cases had decreased significantly since their peak in August 2022. However, clade II mpox is still circulating globally with outbreaks in many countries.
Several outbreaks of mpox caused by different clades of the virus have occurred in different countries, with different modes of transmission and levels of risk. Outbreaks are ongoing in some countries. Mpox was first detected in humans in the DRC in 1970, and is endemic to countries in Central and West Africa.
Summary
Definition
History and exam
Other diagnostic factors
- fatigue/asthenia/malaise
- myalgia
- headache
- sore throat
- backache
- cough
- 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
- occupational exposure
- unprotected 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)
- sexually transmitted infection (STI)
- acute or chronic skin conditions (severe disease)
Diagnostic tests
1st tests to order
- reverse-transcription polymerase chain reaction (RT-PCR)
- CBC
- urea and electrolytes
- LFTs
- sexually transmitted infection (STI) 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, FFPH, FMedSci, DTM&H
Emeritus Professor
London School of Hygiene & Tropical Medicine
London
UK
Disclosures
JW declares that he has no competing interests.
Peer reviewer acknowledgements
BMJ Best Practice topics are updated on a rolling basis in line with developments in evidence and guidance. The peer reviewers listed here have reviewed the content at least once during the history of the topic.
Disclosures
Peer reviewer affiliations and disclosures pertain to the time of the review.
References
Key articles
World Health Organization. Clinical management and infection prevention and control for monkeypox: interim rapid response guidance, 10 June 2022. Jun 2022 [internet publication].Full text
Reference articles
A full list of sources referenced in this topic is available here.
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