Chikungunya, a debilitating tropical disease causing severe joint pain, is now being transmitted by mosquitoes across much of Europe, according to a study published this week in the Journal of Royal Society Interface. The findings indicate a significant expansion of the disease’s reach, driven by rising temperatures and the spread of the invasive Asian tiger mosquito.
Researchers at the UK Centre for Ecology and Hydrology (UKCEH) found the minimum temperature required for the virus to incubate within the mosquito is 2.5C lower than previously estimated. This “quite shocking” difference, according to lead author Sandeep Tegar, means infections are now possible for over six months of the year in Spain, Portugal, Italy, and Greece, and for three to five months in Belgium, France, Germany, and Switzerland. The study analyzed data from 49 previous investigations into chikungunya virus in Asian tiger mosquitoes.
“The rate of global warming in Europe is approximately double the rate of global warming at a global scale, and the lower temperature limit for virus spread matters a lot, so our new estimates are quite shocking,” Tegar said. “The northward expansion of the disease is just a matter of time.”
The Asian tiger mosquito, Aedes albopictus, which bites during daylight hours, has been steadily moving north across Europe as temperatures increase. While detected in the UK, it is not yet established there. The mosquito’s ability to transmit chikungunya, alongside other viruses like dengue and Zika, was highlighted by Dr. Steven White, also at UKCEH. “Twenty years ago, if you said we were going to have chikungunya and dengue in Europe, everybody would have said you were mad: these are tropical diseases. Now everything’s changed. This is down to this invasive mosquito and climate change – it really is as simple as that.”
Large-scale outbreaks of chikungunya, with hundreds of cases, were reported in France and Italy in 2025, a significant increase from previous years. France recorded over 800 cases in 2025, compared to approximately 30 cases over the preceding decade. These outbreaks were linked to infected travelers returning from tropical regions, particularly French overseas territories, where the virus is endemic.
The World Health Organization (WHO) acknowledges the growing threat. Dr. Diana Rojas Alvarez, who leads the WHO’s team on viruses transmitted by insect and tick bites, stated that the study indicates transmission in Europe “might become even more evident over time.” She emphasized the potentially devastating impact of chikungunya, noting that up to 40% of those infected continue to experience arthritis or severe pain five years after the initial infection.
While vaccines exist, they are costly. Public health officials are focusing on preventative measures, including educating communities about eliminating standing water where mosquitoes breed, and advising the use of long, light-colored clothing and insect repellent. Surveillance systems are also being urged to track the spread of both the mosquito and the virus.
The virus is transmitted when an uninfected mosquito bites an infected person, allowing the virus to replicate within the mosquito. If the incubation period within the mosquito is shorter than its lifespan, the virus can then be transmitted to another person through a subsequent bite. The UKCEH team is currently investigating the possibility of year-round Asian tiger mosquito activity in southern Europe, which could lead to larger and more frequent outbreaks as the continent continues to warm.
The UK has seen a rise in imported cases, with a record 73 reported between January and June 2025, nearly three times the number reported in the same period in 2024. Dr. White stressed the importance of preventing the Asian tiger mosquito from establishing itself in the UK, given its capacity to transmit multiple serious infections.
