Research and analysis

Outbreaks under monitoring: week 43 (week ending 26 October 2025)

Updated 30 October 2025

Disease or pathogen	Avian influenza A(H5)
Location	Bangladesh and Cambodia
Status	New incident
Reporting date	29 September and 21 October 2025
Summary	On 21 October 2025, a human case of avian influenza A(H5) was reported from Sylhek Division, Bangladesh. This is the 12th human case of avian influenza A(H5) in Bangladesh since 2003. The case became symptomatic on 27 July 2025 and was hospitalised on 1 August 2025. Oropharyngeal and nasopharyngeal swabs were collected from the case on 4 August 2025 and tested positive for avian influenza A(H5) virus by reverse transcription-polymerase chain reaction (RT-PCR). The subtype of the virus was not reported. The case was discharged following recovery on 7 August 2025. The case reported no history of travel or exposure to backyard poultry, but his family had exposure to chicken from a local market days before onset of his symptoms. Samples from contacts of the case tested negative for avian influenza A(H5) virus. In Cambodia, a human case of avian influenza A(H5N1) was reported from Takeo Province. The case presented with fever, cough and dyspnoea on 1 September 2025 and was hospitalised on 5 September 2025. Oropharyngeal and nasopharyngeal swabs were collected from the case on 7 September 2025 and tested positive for avian influenza A(H5N1) virus by RT-PCR. Between 1 and 21 October 2025, Cambodia has reported 17 human cases of avian influenza A(H5N1) and at least 8 deaths. All cases were associated with backyard poultry contact. Clade typed cases identified as belonging to clade 2.3.2.1e. Since December 2021, 7 detections have been reported in the UK, one in 2022, 4 in 2023, one in 2024, and one in 2025.
Further information	Avian influenza: managing human exposures to incidents in birds or animals NaTHNaC country information page: Bangladesh and Cambodia.

Disease or pathogen	Chikungunya
Location	France and the Hong Kong
Status	Situation update
Reporting date	22 to 26 October 2025
Summary	In France, 749 locally acquired cases of chikungunya [in French] have been reported between 1 May and 20 October 2025. This is an addition of 20 cases since the last report on 15 October 2025. The number of locally acquired cases recorded in 2025 is the highest since 2010. For the first time ever, locally acquired cases were reported in the departments of Grand Est, Bourgogne-Franche-Comte, Centre-Val de Loire and Nouvelle-Aquitaine. The World Health Organization (WHO) states the increased incidence in 2025 is linked to the chikungunya outbreak in Reunion and the rest of the Indian Ocean region. On 26 October 2025, the Centre for Health Protection (CHP) reported the first ever locally acquired case of chikungunya in Hong Kong. According to the CHP, the case is an 82-year-old female resident of Wong Tai Sin who became symptomatic on 18 October 2025. Preliminary investigations revealed that the case travelled to Qingyuan in Guangdong Province, China, in late August 2025 but had no travel history during her incubation period. In the UK, an increase in travel-associated chikungunya cases has been reported in 2025. Most cases reported travel to Sri Lanka, India and Mauritius. No locally acquired cases of chikungunya have ever been reported in the UK.
Further information	Chikungunya: transmission, epidemiology and guidance   Chikungunya: epidemiology in England, Wales and Northern Ireland    NaTHNaC country information page: France and Hong Kong.

Disease or pathogen	Ebola virus disease
Location	Democratic Republic of the Congo (DRC)
Status	Situation update
Reporting date	4 September to 23 October 2025
Summary	On 4 September 2025, the DRC’s Ministry of Health (MoH) declared an outbreak [in French] of Ebola virus disease (EVD) in Bulape health zone, Kasai Province. As of 19 October 2025, 64 EVD cases (53 confirmed and 11 probable cases) including 45 deaths (34 confirmed and 11 probable deaths) have been reported in Bulape health zone. A total of 19 patients have recovered and since been discharged from Ebola treatment centres. On 19 October 2025, the last EVD patient was discharged from hospital following recovery, triggering a 42-day countdown to declaration of the outbreak being over pending no further cases. The Africa Centres for Disease Control and Prevention (CDC) reported that as of 22 October 2025, 1,735 followed up contacts (out of 1,787 listed contacts) have completed their 21 day monitoring period. 36,314 vaccines have been administered since the outbreak began. The WHO assessed the public health risk of this outbreak as high at the national level, moderate at the regional level and low at the global level. 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	Mpox (clade I)
Location	Multi-region (United States and Europe)
Status	New incident
Reporting date	20 to 24 October 2025
Summary	In October 2025, community transmission of clade Ib mpox was reported for the first time in several European countries (Italy, the Netherlands, Portugal and Spain), the USA and Malaysia. Some of the new cases in these countries (USA (3 cases), Spain (1 case) and the Netherlands (1 case) have been among gay, bisexual, and other men who have sex with men (GBMSM), and mark the first reported detections of clade Ib mpox in GBMSM. On 10 October 2025, a confirmed clade Ib [in Spanish] mpox case was reported in Madrid, Spain. The individual was a male who had symptom onset on 3 October 2025. This is the first autochthonous transmission of clade Ib mpox in Spain, and the first reported clade Ib mpox case within the GBMSM community in the EU/EEA. The European Centre for Disease Prevention and Control states that given the low probability of infection and the very low impact of an infection, the risk to the GBMSM community is low. On 17 October 2025, California’s Department of Public Health (CPDH) reported 3 confirmed clade I mpox cases (subtype not specified). These cases were not stated to be epidemiologically linked. All 3 cases were detected within GBMSM. CDPH states that the overall public health risk of clade I mpox to the population in California and the US continues to be low. On 20 October 2025, the Netherlands National Institute for Public Health and the Environment (RIVM) reported the first confirmed case of clade Ib mpox in the Netherlands. The individual was not vaccinated and reported sexual activity within the GBMSM community. RIVM stated that the risk of further transmission is low. On 24 October 2025, the WHO reported community transmission of clade Ib mpox in Italy, Spain, Portugal, the Netherlands, USA and Malaysia for the first time. An exported case from Malaysia to Belgium was also reported. In the UK, clade Ib and clade IIb mpox cases have been reported. As of 16 October 2025, 16 clade Ib mpox cases have been reported, all in England. The last reported UK case was in August 2025. Most of the cases have direct or indirect travel links to countries where clade Ib mpox is circulating. Currently, no clade Ib mpox cases have been detected in the GBMSM community in the UK.
Further information	Mpox: guidance Mpox clade Ib and clade IIb outbreak: UK epidemiological overview Mpox: technical assessment NaTHNaC country information page: Italy, Malaysia, Netherlands, Portugal, Spain,  United States.)

Disease or pathogen	Rift Valley fever
Location	Mauritania and Senegal
Status	Situation update
Reporting date	26 September to 26 October 2025
Summary	On 26 September 2025, Senegal’s Ministry of Health and Public Hygiene reported an outbreak [in French] of Rift Valley fever (RVF) in the Saint-Louis region. As of 26 October 2025, 324 RVF cases [in French], including 25 deaths, have been reported. Most cases have been reported in Saint-Louis region (265 cases). This is an increase of 79 cases and 4 deaths since the last report [in French]. The Africa CDC has stated that males account for 65% of confirmed cases and 73% of all cases have been identified in rural communities. On 27 September 2025, Mauritania’s MoH [in Arabic] reported a fatal RVF case in Rosso City. The MoH states that the case had returned from an unspecified neighbouring country. Ten contacts of the fatal case were initially identified. Between 1 January and 19 October 2025, 149 RVF cases (42 confirmed) and 14 deaths  have been reported across 13 regions of Mauritania. This is an increase of 12 confirmed cases and 2 deaths since the last report with data valid up to 14 October 2025. Genomic analysis suggests that the current RVF outbreak in Senegal is directly linked to the previous detections in Senegal (Fatick in 2020 and Matam in 2022) and Mauritania (2020). 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