Chikungunya: A Growing Threat in Europe
A painful tropical illness known as chikungunya can now be transmitted by mosquitoes across much of Europe, according to a recent study.
The impact of rising temperatures associated with climate change means that chikungunya could be spread for over six months of the year in southern European countries such as Spain and Greece, and for about two months in southeastern England. Researchers suggest that ongoing global warming will soon allow the disease to move even further north.
This analysis is significant because it’s the first comprehensive look at how temperature affects the incubation time of the chikungunya virus within the Asian tiger mosquito, a species that has increasingly invaded Europe. Researchers noted that the minimum temperature for possible infections is about 2.5°C lower than previous estimates—an unexpectedly large difference.
Initially detected in Tanzania in 1952, chikungunya was largely restricted to tropical areas where it causes millions of infections each year. The disease is notorious for causing severe and lasting joint pain, which can be particularly dangerous for young children and older adults.
In recent years, although a handful of cases have popped up in over ten European countries, significant outbreaks, with hundreds of cases, have occurred in France and Italy, notably in 2025.
Sandeep Tegar from the UK Centre for Ecology and Hydrology remarked, “Europe’s rate of warming is roughly twice that of the global average, making our revised temperature estimates rather startling. The northward spread of chikungunya is just a matter of time.”
Dr. Steven White, also from UKCEH, commented on the drastic shift in the landscape of infectious diseases in Europe over the past two decades. “Twenty years ago, talking about chikungunya and dengue in Europe would have seemed absurd; those things were just tropical diseases. But, with the invasive mosquito and climate change, everything has changed.”
The scale of recent change is troubling. France had documented about 30 chikungunya cases over the previous decade, but last year, that number surged to over 800. Many were attributed to travelers returning from tropical regions like Réunion.
The Asian tiger mosquito, which is active during the day, is advancing northward as temperatures rise across Europe. Although it has been spotted in the UK, it hasn’t fully established itself yet. While there are expensive vaccines for chikungunya, the best defense is still preventing mosquito bites.
Dr. Diana Rojas Alvarez, leading the WHO’s team focused on insect-borne viruses, highlighted the significance of this research, stating that it indicates likely increased transmission in Europe over time. Chikungunya can have long-lasting effects, with up to 40% of those infected suffering severe pain or arthritis even five years later.
She also pointed out that while climate greatly impacts the spread, there’s still an opportunity for Europe to manage the situation. Public education on eliminating standing water, where mosquitoes breed, is crucial, along with protective measures like wearing light-colored clothing and using repellents. Health authorities need to establish adequate surveillance systems, as well.
The lifecycle of the chikungunya virus involves entering a mosquito’s gut when it bites an infected individual. After a certain period, the virus can be passed in the mosquito’s saliva, potentially infecting another person during the next bite. However, if this incubation time exceeds the mosquito’s lifespan, transmission cannot occur.
The study, published in the Journal of Royal Society Interface, analyzed data from 49 earlier studies to better determine the virus’s incubation time across various temperatures. The findings reveal that transmission can now happen at temperatures as low as 13°C-14°C, extending the risk of outbreaks for longer periods across southern Europe and into countries like Belgium, France, and Germany, which were previously considered less vulnerable.
This new information allows local authorities to target specific locations and months for possible interventions. Outbreaks often begin when infected travelers return from tropical areas and get bitten by local mosquitoes, which then spread the virus. Historically, colder winters in Europe have served as a natural barrier to limit mosquito activity and disease spread.
However, scientists are now observing year-round activity of tiger mosquitoes in southern Europe, which suggests that chikungunya could become more common as the climate warms. The UKCEH team is looking into this situation further, with a view that bigger outbreaks could be on the horizon due to the absence of that natural barrier.
While there have been no local chikungunya transmissions reported in the UK yet, there has been a notable increase in recorded cases among travelers returning from abroad. From January to June 2025, there were 73 cases, nearly three times the number reported during the same period in 2024.
Dr. White emphasized the need for continued efforts to prevent the establishment of the tiger mosquito in the UK, as it’s a highly invasive species capable of transmitting serious infections, including chikungunya, dengue, and Zika viruses.
