Chikungunya virus, a debilitating tropical disease spread by mosquito bites, poses a growing health threat in Europe, with new research indicating it can now be transmitted at temperatures as low as 13°C (55°F). This finding, from researchers at the UK Centre for Ecology & Hydrology (UKCEH), expands the previously understood temperature range for transmission and suggests a wider geographic area and longer transmission season are now at risk.
The virus, rarely fatal but often causing prolonged and severe joint pain, has historically been confined to tropical regions. However, the study, published in the Journal of the Royal Society Interface, demonstrates that the Asian tiger mosquito (Aedes albopictus), now established in parts of Europe, can effectively spread chikungunya at lower temperatures than previously believed. This is a significant shift, as prior research suggested a minimum transmission temperature of 16-18°C (61-64°F).
Record Outbreaks and Expanding Range
The increased risk is already being observed. In 2025, France and Italy experienced record numbers of local chikungunya outbreaks. The Asian tiger mosquito, responsible for these outbreaks and also an increasing number of dengue fever cases in those countries, is currently only occasionally detected in south-east England and hasn’t yet become established there. However, researchers warn that warming temperatures could change this in the coming years, particularly in south-east England.
The UKCEH has developed a risk map illustrating the potential for chikungunya transmission across Europe, including the UK. This map highlights that the threat of virus transmission could last for several months in warmer regions where the tiger mosquito is already present. Currently, the risk in the UK is low, limited to East Anglia and the south-eastern corner of England during July and August, and for one of those months in isolated pockets elsewhere in the south.
Lower Temperature Threshold Expands Risk
The key finding of the study is the lowered temperature threshold for viral transmission. “Europe is warming rapidly, and the tiger mosquito is gradually expanding northwards through the continent,” explains Sandeep Tegar, an epidemiological modeller at UKCEH who led the study. “The lower temperature threshold that we have identified will therefore result in more areas—and more months of the year—becoming potentially suitable for transmission.”
This means that areas previously considered too cool for sustained transmission may now be vulnerable, and the transmission season could be extended. The researchers emphasize that identifying specific locations and the months of potential transmission will allow local authorities to implement targeted interventions to reduce the risk of outbreaks.
Climate Change and Invasive Species
The increasing spread of chikungunya and other mosquito-borne viruses in Europe is directly linked to climate change and the globalization of travel and trade. Warmer temperatures not only create more suitable conditions for mosquito populations to thrive but also increase the rate at which viruses replicate within the insect, enhancing transmission potential. The arrival of invasive mosquito species, like the Asian tiger mosquito, through global transport further exacerbates the problem.
The Asian tiger mosquito often bites returning travelers infected with viruses like chikungunya and dengue, then transmits the virus to other people in the local population, initiating outbreaks. In the UK, there were a record 73 travel-related cases of chikungunya reported between January and June 2025, compared to 27 cases during the same period in 2024, demonstrating the increasing exposure risk for travelers.
Public Health Response and Prevention
The UK Health Security Agency (UKHSA) coordinates a national surveillance program to monitor for the presence of the Asian tiger mosquito in the UK, focusing on high-risk areas such as airports, ferry terminals, and distribution centers.
Effective prevention strategies include:
- Surveillance of potential mosquito breeding sites, such as stagnant water, and their removal.
- Fumigation of breeding areas and open spaces, as well as the homes of infected individuals.
- Targeted public health resources in high-risk areas, including potential vaccine distribution.
- Public education on measures to prevent mosquito bites.
UKCEH is also developing risk maps for other mosquito-borne viruses, including dengue fever, Zika, and West Nile virus, to provide a comprehensive assessment of the evolving threat landscape in Europe. A Europe-wide risk map for dengue fever was recently produced, identifying potential hotspots.
Dr. Steven White of UKCEH emphasizes the importance of continued efforts to prevent the Asian tiger mosquito from becoming established in the UK. “It is important that there is continued action to try to prevent the tiger mosquito from establishing in this country because this highly invasive species is capable of transmitting several infections that can cause serious health conditions including chikungunya, dengue and Zika viruses.”
The changing climate and the spread of invasive species necessitate ongoing vigilance and proactive public health measures to protect populations across Europe from the growing threat of mosquito-borne diseases.
