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Last reviewed: 10 Nov 2024
Last updated: 10 Dec 2024
10 Dec 2024

WHO declares mpox outbreak in Africa a public health emergency of international concern; first cases of clade Ib mpox detected in US and UK

​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 (reaffirmed on 28 November 2024). 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.

So far in 2024, over 13,000 laboratory-confirmed cases have been reported in Africa, including 55 deaths (as of 2 December 2024). The three countries with the majority of cases are the DRC, Burundi, and Uganda. The number of suspected and confirmed cases has been estimated to be higher as many cases are not laboratory-confirmed due to limited diagnostic capacity in some African countries.[12]

Although the epidemiology is not fully understood, there are currently 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 which has been rapidly spreading and reaching neighboring countries which 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.

At the time of publication, travel-related cases of clade Ib mpox have now also been reported in some countries outside of Africa including India, Sweden, Thailand, Germany, the US, and the UK.

The first case of clade Ib mpox detected in the UK was reported on 30 October 2024. The case had recently traveled to countries in Africa currently experiencing outbreaks of clade Ib mpox. Three further cases were detected in household contacts of the first case. A fifth case was reported on 29 November 2024 in Leeds. The case had recently returned from Uganda, and has no links to the previous four identified cases (who have all recovered). Close contacts of the cases are being followed up, and will be tested and vaccinated as needed. The wider risk to the UK population remains low.[26]​​

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.​[27]

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 2022 global outbreak, or whether current vaccines are effective against the new variant.

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.

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.

See Epidemiology

Original source of update

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
  • 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
  • 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 tests

1st tests to order

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

Tests 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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