Research and analysis

Outbreaks under monitoring: week 47 (week ending 23 November 2025)

Updated 4 December 2025

Disease or pathogen	Marburg disease
Location	Ethiopia
Status	New incident
Reporting date	12 to 23 November 2025
Summary	On 14 November 2025, the World Health Organization (WHO) confirmed the country’s first Marburg disease (MARD) outbreak, following laboratory testing of samples from the cluster of suspected viral haemorrhagic fever (VHF) cases (Facebook login required). As of 23 November 2025, 10 confirmed cases and 5 confirmed deaths have been reported. 57 persons are under laboratory investigation. Genomic analysis suggests that the Marburg virus detected in this outbreak is of the same strain as the virus reported in previous outbreaks in East African countries. The source of the infection has not yet been identified although initial investigations show the presence of fruit bats in the area (a reservoir of Marburg virus). National health authorities are scaling up response measures including screening, testing, contact tracing and public sensitization to control the outbreak. The WHO and other partners are supporting Ethiopia’s health authorities through deployment of a team of responders with expertise in responding to VHF outbreaks, as well as providing other medical supplies and equipment. On 23 November 2025, Kenya Ministry of Health reported that the Kenyan Government has enhanced cross-border surveillance at airports and all other points of entry from Ethiopia. No known human Marburg cases have been reported in the UK. The risk of this outbreak to the UK public is currently considered very low.
Further information	Marburg virus disease: origins, reservoirs, transmission and guidelines Viral haemorrhagic fever: ACDP algorithm and guidance on management of patients Marburg contact tracing (collection page) Ebola and Marburg: returning workers scheme NaTHNaC country information page: Ethiopia

Disease or pathogen	Rift Valley fever
Location	Mauritania and Senegal
Status	Situation update
Reporting date	26 September to 23 November 2025
Summary	On 26 September 2025, Senegal’s Ministry of Health and Public Hygiene reported an outbreak (Facebook login required) of Rift Valley fever (RVF) in the Saint-Louis region. As of 22 November 2025, 494 RVF cases (Facebook), including 31 deaths, have been reported. Most cases have been reported in Saint-Louis region (351 cases). This is an increase of 35 cases since the last report (Facebook). Genomic analysis suggests that the current outbreak is directly linked to the previous detections in Senegal (Fatick in 2020 and Matam in 2022) and Mauritania (2020). Between 1 January and 21 November 2025, 52 confirmed cases and 15 deaths, have been reported across 14 regions of Mauritania. This is an increase of 6 confirmed cases and one death since the last report with data up to 30 October 2025. The WHO currently assesses the overall risk of RVF outbreaks in Mauritania and Senegal as high at the national levels, moderate at the regional level and low at the global level. No known human RVF cases have been reported in the UK.
Further information	Viral haemorrhagic fevers: origins, reservoirs, transmission and guidelines NaTHNaC country information page: Mauritania and Senegal