Chikungunya Virus: Europe at Risk as Tiger Mosquitoes Adapt to Colder Climates

Chikungunya, a debilitating tropical disease historically confined to regions like Tanzania where it was first detected in 1952, is now spreading across Europe, raising concerns for public health officials. While previously considered a disease of the tropics, significant outbreaks began to occur in Europe in 2025, with over 800 cases reported in France and hundreds in Italy within a single year.

The spread is typically initiated by infected travelers returning from tropical areas who are then bitten by local Aedes albopictus mosquitoes – commonly known as Asian tiger mosquitoes – which then transmit the virus further. This mosquito species has been increasingly invasive in Europe over recent decades.

Lower Temperature Thresholds Expand Risk

A recent study from the UK Centre for Ecology & Hydrology (UKCEH), published in the Journal of the Royal Society Interface, reveals that the Asian tiger mosquito can transmit chikungunya at lower temperatures than previously understood. The research indicates that virus transmission can occur at temperatures as low as 13-14 degrees Celsius (approximately 55-57 degrees Fahrenheit), roughly 2.5 degrees Celsius lower than prior estimates.

This finding is particularly significant because global warming is extending the period during which mosquitoes are active. Longer and more frequent warm spells increase the number of weeks – and in some cases, months – during which local virus transmission is possible. The study analyzed the effect of temperature on the incubation time of the virus within the mosquito.

The implications of these findings are substantial. As Steven White, of UKCEH, told The Guardian, “For twenty years ago, you would have been called mad if you said we would be getting chikungunya in Europe: it’s a tropical disease. Now everything has changed.”

Chikungunya: Symptoms and Impact

Chikungunya virus causes a range of symptoms, most notably severe and prolonged joint pain, which can be extremely debilitating. While rarely fatal, the disease can be serious, particularly for young children and older adults. The illness typically begins with fever and muscle pain, followed by the characteristic joint pain that can persist for weeks, months, or even years.

The increasing prevalence of chikungunya in Europe is not occurring in isolation. The Asian tiger mosquito is also responsible for a growing number of dengue fever cases in countries like France, and Italy. The mosquito is capable of transmitting Zika virus, adding another layer of public health concern.

Expanding Geographic Risk

The changing climate is expanding the geographic range of the Asian tiger mosquito, putting more European cities at risk. Cities like Paris, Vienna, and Zagreb are now considered increasingly vulnerable to outbreaks of dengue, Zika, and chikungunya. The European Environment Agency has projected a further spread of climate-sensitive infectious diseases and a higher overall disease burden in Europe in the coming years.

The mosquito’s adaptability – including its ability to lay eggs in man-made water reservoirs and produce drought-resistant eggs – has facilitated its spread across the continent. Global trade also plays a role, with mosquitoes sometimes transported via items like potted plants and used tires.

Current Risk and Future Outlook

Currently, the risk of local chikungunya transmission in the United Kingdom remains very low, as the Asian tiger mosquito is only occasionally detected in south-east England and is not yet established. However, researchers warn that warming temperatures could lead to the mosquito becoming established in the UK in the coming years, posing a disease risk, particularly in the south-east.

The European Climate and Health Observatory, established as part of the EU Adaptation Strategy, is working to track, analyze, and prevent climate-related impacts on human health. This includes monitoring the spread of vector-borne diseases like chikungunya and developing strategies to improve health resilience.

The findings underscore the urgent need for continued research into the effects of climate change on infectious disease transmission and the importance of proactive public health measures to mitigate the risks. While the situation is evolving, understanding the changing dynamics of chikungunya transmission is crucial for protecting public health across Europe.