Research and analysis
Outbreaks under monitoring: week 40 (week ending 5 October 2025)
Updated 23 October 2025
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| Disease or pathogen | Chikungunya |
|---|---|
| Location | Global |
| Status | Situation update |
| Reporting date | 3 October 2025 |
| Summary | On 3 October 2025, the World Health Organization (WHO) reported a in several countries, including countries that have not recorded a notable increase in number of cases over recent years. According to the WHO, 445,271 chikungunya cases (including suspected and confirmed cases, both locally acquired and imported), and 155 deaths have been reported from 40 countries between 1 January and 30 September 2025. The highest number of cases have been reported in the Region of the Americas (328,920 cases and 115 deaths) and the European Region (56,456 cases and 40 deaths). In the European Region, France and Italy have reported active chikungunya outbreaks in 2025. In France, between 1 May and 29 September 2025, have been reported. 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 and Nouvelle-Aquitaine. The WHO states the increased incidence in 2025 is in Reunion and the rest of the Indian Ocean region. In Italy, between 1 January and 30 September 2025, (including 323 locally acquired and 41 travel associated cases) and no deaths have been reported. The number of locally acquired cases reported in 2025 is the . In Reunion, between 1 January and 14 September 2025, have been reported. A decline in newly reported cases has been observed since 26 April 2025. The WHO states that the variation in case trends among reporting countries makes it difficult to classify the current picture as a global increase in chikungunya cases. However, the risk of further geographical spread of chikungunya to new areas remains noteworthy in the event of limited population immunity, favourable climate conditions for vector establishment, increased human movements and trades and gaps in public health systems. In the United Kingdom (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 |
| Disease or pathogen | Ebola virus disease |
|---|---|
| Location | Democratic Republic of the Congo (DRC) |
| Status | Situation update |
| Reporting date | 4 September to 3 October 2025 |
| Summary | On 4 September 2025, the DRC鈥檚 Ministry of Health of Ebola virus disease (EVD) in Bulape health zone, Kasai province. As of 30 September 2025, (53 confirmed and 11 probable cases) including 42 deaths (31 confirmed and 11 probable cases) have been reported in Bulape health zone. According to the WHO, a in recent weeks and since 30 September 2025, no new EVD cases have been reported. The Emergency Response Coordination Centre of the European Commission reported that as of 3 October 2025, has been provided by humanitarian partners to strengthen the ongoing response to the outbreak. 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 been previously 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 . |
| Disease or pathogen | Legionella |
|---|---|
| Location | France |
| Status | Situation update |
| Reporting date | 3 October 2025 |
| Summary | On 23 September 2025, the Auvergne-Rhone-Alpes Regional Health Agency reported a in Albertville, Savoie department, France. Between 16 September and 3 October 2025, and 2 deaths were reported. This is an increase of 4 cases since the last report on 26 September 2025. Investigations are still ongoing to identify the source of exposure. In the UK, Legionnaires鈥� disease cases follow a seasonal pattern, with a peak number typically reported between June and October. Between 2017 and 2023, 3,276 cases of Legionnaires鈥� disease were reported in the UK. In 2023, 212 of 604 confirmed Legionella exposures (35.1%) were related to travel abroad. |
| Further information |
Legionnaires鈥� disease: guidance, data and analysis |
For more information on the background and methods used in this report, see聽Outbreaks under monitoring: background and methodology.