Research and analysis
Outbreaks under monitoring: week 42 (week ending 19 October 2025)
Updated 23 October 2025
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| Disease or pathogen | Chikungunya |
|---|---|
| Location | France and the United States |
| Status | Situation update |
| Reporting date | 14 to 16 October 2025 |
| Summary | In France, have been reported between 1 May and 13 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 in Reunion and the rest of the Indian Ocean region.聽 In the United States, the reported a confirmed chikungunya case in Nassau County, New York. This is the first locally acquired chikungunya case reported in the United States since 2019. On 15 October 2025, that the case started to experience symptoms in August 2025 after travelling out of the region, however they had not travelled outside of the country. reported that the case was likely bitten by an infected mosquito. The virus has not been detected in local mosquito pools, and there is no evidence of ongoing transmission. 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鈥� Chikungunya: epidemiology in England, Wales and Northern Ireland鈥赌� NaTHNaC country information page: and the |
| Disease or pathogen | Ebola virus disease |
|---|---|
| Location | Democratic Republic of the Congo (DRC) |
| Status | Situation update |
| Reporting date | 4 September to 7 October 2025 |
| Summary | On 4 September 2025, the DRC鈥檚 Ministry of Health (MoH) of Ebola virus disease (EVD) in Bulape health zone, Kasai Province. As of 19 October 2025, (53 confirmed and 11 probable cases) including 45 deaths (34 confirmed and 11 probable deaths) have been reported in Bulape health zone. This is an increase of 2 deaths among previously confirmed cases since the . A total of 19 patients have recovered and since been discharged from an Ebola treatment centre. On , 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 WHO assesses the 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 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: . |
| Disease or pathogen | Middle East respiratory syndrome |
|---|---|
| Location | Saudi Arabia |
| Status | New incident |
| Reporting date | 3 September to 10 October 2025 |
| Summary | Between 1 January and 6 October 2025, cases were reported in Saudi Arabia. The was reported in August 2025. The imported cases of MERS. 5 cases and 2 deaths were reported between 2012 and 2018 with 3 of these cases classed as imported cases and 2 cases were secondary cases in close family members. |
| Further information |
MERS-CoV: clinical management and guidance NaTHNaC country information page: |
| Disease or pathogen | Mpox (clade I) |
|---|---|
| Location | Multi-region (United States and Europe) |
| Status | New incident |
| Reporting date | 14 to 16 October 2025 |
| Summary | During epidemiological week 41 of 2025 (13 to 19 October 2025), the first clade I聽 mpox cases with no travel history to a region where clade I mpox is known to be in circulation was reported in the United States and in Europe. On 14 October 2025, the聽 in the City of Long Beach, California, was confirmed. This is the seventh clade I mpox case in the United States, and the first without known travel history. 聽The city Health Department is reviewing the cases potential source of exposure and is conducting contact tracing. On 16 October 2025, the reported a new confirmed case of clade I mpox in an adult that had no recent travel History. A was issued by the California Department of Public Health (CDPH) on 17 October 2025 stating that 3 cases of clade I mpox had been detected with no recent history of international travel. The clade subtype was not specified. These cases were not stated to be epidemiologically linked. All 3 cases were detected within the gay, bisexual, and other men who have sex with men (GBMSM) community. 聽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 , a confirmed clade Ib mpox case was reported in Madrid, Spain. The individual was a male who had symptom onset on 3 October 2025 and reported having sex with two men who did not have signs or symptoms of mpox. The case reported no recent international travel history. Laboratory and clade type confirmation was received on . This is the first autochthonous transmission of clade I 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 estimated to be low. 聽 In the聽UK,聽clade Ib and clade IIb聽mpox cases have been reported. As of 16 October 2025,聽聽have been reported, all in England. Most of the cases have direct or indirect travel links to聽countries where clade Ib mpox is circulating. |
| Further information |
Mpox: guidance Mpox clade Ib and clade IIb outbreak: epidemiological overview NaTHNaC country information page: |
| Disease or pathogen | Rift Valley fever |
|---|---|
| Location | Mauritania and Senegal |
| Status | Situtation update |
| Reporting date | 26 September to 17 October 2025 |
| Summary | On 26 September 2025, Senegal鈥檚 Ministry of Health and Public Hygiene of Rift Valley fever (RVF) in the Saint-Louis region. As of 15 October 2025, , including 21 deaths, have been reported. Most cases have been reported in Saint-Louis region (197 cases). This is an increase of 98 cases and 2 deaths since the . The was in Saint-Louis region in 2020 and resulted in 9 cases. On 27 September 2025, 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 14 October 2025, have been reported across 13 regions of Mauritania. This is an increase of 81 cases (including confirmed cases) and 6 deaths since previous media reports valid for , with geographical expansion to 10 more regions. 聽suggests that the current RVF outbreak in Senegal is directly linked to the聽previous outbreaks聽in Senegal (Fatick in 2020 and Matam in 2022) and Mauritania (2020). No known聽human RVF cases have been reported in the聽UK. |
| Further information |
Viral haemorrhagic fevers: origins, reservoirs, transmission and guidelines NaTHNaC country information page: |