Research and analysis

Outbreaks under monitoring: week 49 (week ending 7 December 2025)

Updated 11 December 2025

Disease or pathogen	Ebola virus disease
Location	Democratic Republic of the Congo
Status	Situation update
Reporting date	4 September to 1 December 2025
Summary	On 1 December 2025, the Democratic Republic of the Congo (DRC) declared an end to the Ebola virus disease (EVD) outbreak in Kasai Province. The declaration follows a 42-day countdown period (twice the incubation period of the virus) during which no new reported confirmed cases were reported. 64 EVD cases (53 confirmed and 11 probable cases) including 45 deaths (crude case fatality rate of 70%) were reported during this outbreak. According to the World Health Organization (WHO), 5 EVD cases (including 3 deaths) were reported among healthcare workers (4 nurses and one laboratory technician). The epicentres of the outbreak included Dikolo (26 cases, 15 deaths) and Bulape (24 cases, 22 deaths) health areas, which together accounted for 78.1% of the total cases reported and 82.2% of all deaths. Over 47,500 individuals were vaccinated against Ebola. The DRC will now begin a 90-day period of enhanced surveillance and will run a survivor care programme with support from WHO to provide holistic post-recovery support for those that have recovered from Ebola infection. WHO reported that existing polio infrastructure and expertise in Kasai province helped in the rapid and coordinated outbreak response.  Imported cases of Ebola disease are very rare in the UK. Four confirmed cases, and no deaths, have previously been reported in the UK. The last reported confirmed case was in 2014.
Further information	Ebola: overview, history, origins and transmission  Ebola virus disease: clinical management and guidance  Ebola and Marburg haemorrhagic fevers: outbreaks and case locations NaTHNaC country information page: Democratic Republic of the Congo

Disease or pathogen	Marburg disease
Location	Ethiopia
Status	Situation update
Reporting date	12 to 7 December 2025
Summary	On 14 November 2025, the WHO confirmed the country’s first Marburg disease outbreak in Jinka town, following laboratory testing of samples from a cluster of suspected viral haemorrhagic fever cases (Facebook login required). As of 7 December 2025, 13 confirmed cases and 8 confirmed deaths have been reported. This is an increase of one confirmed case since the last report. 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 confirmed the presence of fruit bats (a reservoir of Marburg virus) in the area. On 3 December 2025, Gilead Sciences announced the delivery of 1,200 vials of the antiviral remdesivir to Ethiopia to aid in the outbreak response. The United States Government has donated 2,500 doses (Facebook login required) of the investigational cAd3-Marburg vaccine, which will be used in a rapid stage 2 clinical trial starting on 8 December 2025, targeting healthcare workers and high-risk groups. 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	Middle East respiratory syndrome
Location	France
Status	New incident
Reporting date	4 December 2025
Summary	On 4 December 2025, Sante Publique France (French) reported 2 confirmed Middle East respiratory syndrome (MERS) cases who recently travelled to the Arabian Peninsula. These cases presented with clinical symptoms compatible with MERS-coronavirus infection. Both cases were isolated for hospital treatment.  Contacts of the cases (who were part of the same travel group) remain under monitoring. No secondary cases have been identified. The last cases of MERS in France were reported in 2013, in an individual that had returned from abroad and a secondary case who had shared the same hospital room. According to WHO, between 2012 and 16 November 2025, 2,630 MERS cases have been reported worldwide. The UK has previously reported imported cases of MERS. 5 cases and 2 deaths were reported between 2012 and 2018, with 3 of these classed as imported cases and 2 as secondary cases in close family members.  The risk of infection with MERS to UK residents in the UK remains very low. While the risk of infection with MERS-coronavirus to UK residents travelling to the Middle East is very low, it may be higher in those with exposure to specific risk factors within the region, such as camels (or camel products) or the local healthcare system.
Further information	UKHSA risk assessment of MERS-CoV MERS-CoV: clinical management and guidance NaTHNaC country information page: France

Disease or pathogen	West Nile virus
Location	Switzerland
Status	New incident
Reporting date	4 December 2025
Summary	On 4 December 2025, the Ticino Department of Health and Social Affairs reported the first-ever autochthonous human case (Italian) of West Nile virus (WNV) in Switzerland. The case was detected in Ticino and presented with symptoms of meningoencephalitis and was later hospitalised. Laboratory testing confirmed WNV infection. According to the report, the detection of the WNV case is not unexpected as WNV had been detected in mosquitoes in 2025 in Ticino during routine mosquito surveillance. No known locally acquired human WNV case have been reported in the UK. However, there is an existing risk to UK residents who travel to endemic areas abroad. Between 2000 and June 2025, a total of 7 confirmed cases of WNV infection in humans were recorded in UK residents, all acquired through travel. The probability of a human WNV outbreak in the UK is currently considered very low.
Further information	HAIRS risk assessment: West Nile virus West Nile virus: epidemiology, diagnosis and prevention Surveillance and updates for West Nile virus infection NaTHNaC country information page: Switzerland