Epidemiological update: Mpox due to monkeypox virus clade I

According to the Africa CDC Epidemic Intelligence Report issued on 23 August 2024 [1], over 20 000 mpox cases have been reported from 13 African Union Member States so far in 2024, including 3 311 confirmed cases and 582 deaths (case fatality; CF 2.9%). Of these, 19 667 cases (16 706 suspected and 2 961 confirmed) including 575 deaths (CF 2.9%) were reported from all provinces in the DRC where MPXV subclade Ia and Ib circulate, representing over 90% of the cases reported on the African continent to date. MPXV clade I and clade II both circulate in different countries on the continent.

Confirmed mpox cases due to MPXV subclade Ia or Ib have also been reported in five of the eight countries neighbouring DRC: 

• Clade Ia: Republic of the Congo (21 confirmed cases and 141 suspected) and Central African Republic (45 confirmed cases), both of which reported cases in 2023;
• Clade Ib: Burundi (190 confirmed and 512 suspected cases), Rwanda (four confirmed cases), and Uganda (three confirmed cases). 

In addition, Kenya reported one person infected with MPXV clade Ib in 2024 and another where the clade is still unknown, and Gabon reported one person with mpox on 22 August with travel history to Uganda [1,2]. 

According to the World Health Organisation Disease Outbreak News published on 23 August [3], the people with mpox reported in Rwanda had a travel history to DRC and Burundi. According to epidemiological investigation on those with MPXV infection reported by Uganda, the transmission occurred outside the country. The persons with mpox in Kenya were detected at a point of entry. On 22 August 2024, Gabon published a press release reporting that a man with mpox was detected in the country who had travelled from Uganda where mpox cases due to MPXV clade Ib have been reported [2]. 

So far, the two countries where there is probably ongoing community transmission are DRC and Burundi. However, the data available from several other countries in Africa are not of sufficient quality to rule out more widespread transmission than currently reported. 

Epidemiological situation in the EU/EEA

On August 15, 2024, Sweden reported one person with mpox due to MPXV clade Ib, with a travel history to a country in Africa where MPXV is circulating. Mpox cases due to MPXV clade II have continued to be reported in EU/EEA countries since 2022, although the numbers are low. 

Other cases

On 22 August, Thailand reported the detection of mpox due to MPXV clade Ib in a returning traveller from an African country where MPXV clade Ib is circulating [4]. . 

Risk assessment

The number of people with mpox due to MPXV clade I has increased in recent months alongside a geographical expansion of mpox in African countries where it was not previously documented. More imported mpox cases due to MPXV clade I are likely to be reported by EU/EEA and other countries. 

ECDC published a Rapid Risk Assessment for the EU/EEA of the mpox epidemic caused by monkeypox virus clade I in affected African countries [5] on 16 August 2024. The levels of risk assessed in the document remain unchanged. 

ECDC is monitoring trends of mpox through routine indicator-based surveillance in the EU/EEA and through event-based surveillance globally. An epidemiological update on mpox due to MPXV clade I can also be found on last week’s Communicable Diseases Threat report.

Recommendations

Public health authorities

Case detection and management

• Develop and share information material for clinicians;
• Identify, isolate and test any persons suspected of having mpox (presence of compatible symptoms +/- epi link in the absence of typical skin rash)using a PCR assay able to detect MPXV including clade Ib;
• Thoroughly investigate each case (e.g. exposure history, clinical presentation and evolution, drugs administered, vaccination history, pre-existing conditions, perform genomic sequencing, etc).

Prevention and preparedness

• Travellers to areas with active circulation of MPXV clade I should be made aware of and informed about the possibility of infection, and about which preventive measures to adhere to;
• Implement contact tracing and testing of close contacts of people confirmed with the disease;
• Map laboratory capabilities and capacity;
• Immediately report through event-based surveillance mechanisms (EpiPulse, EWRS, IHR routes)
  • Detection of MPXV clade I
  • Unexpected increase in case numbers
  • Emergence of cases in new risk groups, populations, or settings 
• Ensure consistent reporting in TESSy of virus clade information to facilitate clade-specific analyses. 
• Ensure comprehensive molecular characterisation of MPXVs isolated from mpox cases and upload viral nucleotide sequences to the GISAID or other publicly available database.
• Consider making vaccination available, in addition to other preventive measures, for travellers who are at higher risk of infection, especially those at risk of severe outcomes (e.g. immunocompromised persons) based on an individual risk assessment by their healthcare provider and taking into account the available epidemiological data from the African continent. Risk groups to take into account when making such decisions include specific categories of healthcare workers, people visiting families or planning to have close contact with people in areas with an active circulation of MPXV clade I;
• Consider offering post-exposure vaccination to close contacts of confirmed cases, based on an individual risk assessment by public health authorities.
• Continue implementing national recommendations on mpox vaccination for at-risk groups issued in the EU/EEA following the 2022-23 epidemic;
• Countries should continue awareness campaigns targeting key populations affected in the previous outbreak, with clear, positive, and stigma-free messaging.

People planning to travel to countries where the virus is circulating

• Consult guidance from your national health authorities, ECDC guidance and epidemiological information (particularly on areas where ongoing community transmission is confirmed or presumed);
• Avoid contact with wild animals while in countries where the virus is circulating;
• Refrain from activities that involve close contact, including sexual or otherwise, with people suspected or confirmed as having mpox. 

ECDC contributors (in alphabetical order)

Angela Ancona, Xanthi Andrianou, Sabrina Bacci, Daniel Cauchi, Orlando Cenciarelli, Juliana Reyes, Gianfranco Spiteri

References

1. Africa Centres for Disease Control and Prevention (AfricaCDC). Africa CDC Epidemic Intelligence Weekly Report, August 2024. Addis Ababa: AfricaCDC; 2024. Available at: https://africacdc.org/download/africa-cdc-weekly-event-based-surveillance-report-august-2024/
2. Republique Gabonaise. Ministère de la Santé et des Affaires Sociales. Déclaration du premier cas de MPOX au Gabon. Libreville: Ministère de la Santé et des Affaires Sociales; 2024. Available at: https://www.sante.gouv.ga/9-actualites/1190-declaration-du-premier-cas-de-mpox-au-gabon/
3. World Health Organization (WHO). Disease Outbreak News. Mpox – African Region. Geneva: WHO; 2024. Available at: https://www.who.int/emergencies/disease-outbreak-news/item/2024-DON528
4. Department of Disease Control, Ministry of Public Health - Thailand. The Department of Disease Control revealed the test results from the Department of Science. Confirmed the detection of the "first case of monkeypox clade IB in Thailand", suggesting preventive measures. Facebook. 22 August 2024, 03:06. Available at: https://www.facebook.com/permalink.php?story_fbid=pfbid02iSMxFR3F7wkopqNbwwoZgqsR2UE3ZJ1cSZrQEJrUyYdAu8TTvYnEywN9N5My8qzJl&id=100068069971811
5. European Centre for Disease Prevention and Control (ECDC). Risk assessment for the EU/EEA of the mpox epidemic caused by monkeypox virus clade I in affected African countries. Stockholm: ECDC; 2024. Available at: https://www.ecdc.europa.eu/en/publications-data/risk-assessment-mpox-epidemic-monkeypox-virus-clade-i-africa