Climate Change Opens the Door for Painful Chikungunya Disease to Spread Across Europe

A new scientific analysis warns that chikungunya, a tropical virus known for causing intense and long-lasting pain, can now be spread by mosquitoes across much of Europe. Rising temperatures linked to climate change have significantly widened the window in which transmission is possible, particularly in southern parts of the continent.

Researchers found that in countries such as Spain, Portugal, Italy and Greece, conditions now allow chikungunya infections for more than half the year. In parts of western and central Europe, including France, Germany, Belgium and Switzerland, transmission could occur for several months annually. Even south-east England may face a limited seasonal risk. Scientists say continued warming makes further northward spread increasingly likely.

The study is the first to comprehensively examine how temperature affects the virus’s incubation period inside the Asian tiger mosquito, an invasive species that has steadily expanded its range across Europe in recent decades. Using data from 49 previous studies, the researchers determined that the virus can develop inside mosquitoes at temperatures 2.5°C lower than earlier estimates. The newly identified threshold of around 13–14°C sharply increases the number of regions and months where transmission is possible, compared with the previously assumed minimum of 16–18°C.

Chikungunya was first identified in Tanzania in 1952 and for decades remained largely confined to tropical areas, where it still causes millions of infections annually. The illness is marked by severe joint pain that can persist for months or years and can be life-threatening for young children and older adults. While Europe has seen only sporadic cases in the past, France and Italy experienced outbreaks involving hundreds of cases in 2025.

According to the study’s lead author, Sandeep Tegar of the UK Centre for Ecology and Hydrology, Europe is warming at roughly twice the global average, making the lower temperature limit for transmission especially significant. He described the findings as alarming and said the expansion of the disease further north is now a question of when, not if.

Dr Steven White, also from UKCEH, noted that two decades ago the idea of tropical diseases such as chikungunya or dengue establishing themselves in Europe would have seemed implausible. He said the combination of climate change and the spread of the Asian tiger mosquito has fundamentally altered the situation. In France alone, the number of reported chikungunya cases jumped dramatically last year, largely due to infected travellers returning from overseas territories such as Réunion and being bitten by local mosquitoes.

The Asian tiger mosquito bites during the day and thrives in warmer climates. While it has been detected in the UK, it has not yet become established there. Although vaccines against chikungunya exist, they are expensive, and public health experts stress that avoiding mosquito bites remains the most effective defence.

Dr Diana Rojas Alvarez of the World Health Organization said the study underscores the growing likelihood of local transmission in Europe. She warned that up to 40% of patients can continue to suffer from severe joint pain or arthritis even five years after infection. While climate plays a major role, she said European countries still have an opportunity to limit the mosquito’s spread through surveillance, public awareness and basic preventive measures, such as eliminating standing water, wearing protective clothing and using repellents.

The virus spreads when a mosquito bites an infected person, allowing the virus to develop in the insect before being passed on to another human. If this incubation period exceeds the mosquito’s lifespan, transmission cannot occur. Warmer temperatures shorten this process, increasing the risk of spread.

The researchers stressed that their findings allow for more precise identification of high-risk locations and time periods, helping authorities decide when and where to intervene. Traditionally, cold European winters have halted mosquito activity, preventing outbreaks from carrying over year to year. However, signs of year-round mosquito activity are now emerging in southern Europe, raising concerns that future outbreaks could be larger and more sustained.

While no locally acquired chikungunya cases have yet been recorded in the UK, health officials reported a record 73 imported cases between January and June 2025, nearly three times more than during the same period a year earlier. Experts warn that preventing the Asian tiger mosquito from establishing itself remains crucial, as the species is capable of transmitting several serious viruses, including chikungunya, dengue and Zika.