A painful tropical disease, chikungunya, is now transmissible by mosquitoes across much of Europe, according to new research. Rising temperatures linked to the climate crisis are extending the period during which infections are possible to more than six months in countries like Spain, Greece, and Italy, and for up to two months in southeastern England.
The findings, published this week, suggest that continued global warming will likely push the virus further north in the coming years. The analysis represents the first comprehensive assessment of the effect of temperature on the incubation time of the virus within the Asian tiger mosquito (Aedes albopictus), an invasive species that has become established across Europe.
What is Chikungunya?
Chikungunya virus was first identified in Tanzania in 1952 and historically circulated in tropical regions, where millions of cases occur annually. The disease is characterized by severe and prolonged joint pain, which can be debilitating and, in some cases, fatal for young children and older adults. While rarely fatal, the chronic pain associated with chikungunya can persist for years.
Recent years have seen a small number of cases reported in over ten European countries, but significant outbreaks, with hundreds of cases, occurred in France and Italy in 2025. The virus is spread through the bite of infected mosquitoes, primarily the Asian tiger mosquito, which is active during daylight hours.
Lower Temperature Threshold Raises Concerns
The study revealed that the minimum temperature at which chikungunya can be transmitted is 2.5°C lower than previously estimated – around 13-14°C. This lower threshold is a “quite shocking” difference, according to researchers at the UK Centre for Ecology & Hydrology (UKCEH), who led the study. “The rate of global warming in Europe is about twice the global rate, and the lower temperature limit for virus transmission is very important, so our new estimates are quite shocking,” explained Sandeep Tegar, an epidemiological modeller at UKCEH.
Steven White, also of UKCEH, added, “Twenty years ago, if we had said we’d have Chikungunya and Dengue in Europe, everyone would have thought we were crazy – these are tropical diseases. Now it’s all changed. It’s really as simple as this invasive mosquito and climate change.”
Mapping the Risk Across Europe
Researchers have created a risk map detailing the extent of chikungunya transmission risk across Europe, broken down into 10km square areas. The map indicates that the threat of virus transmission may last for several months each year in warmer parts of the continent. While the tiger mosquito has been detected in the UK, it is not yet established, meaning the current risk of local transmission remains very low. However, researchers warn that warming temperatures could lead to the mosquito becoming established in the UK in the coming years, particularly in southeastern England.
How the Virus Spreads
When a mosquito bites a person infected with chikungunya virus, the virus enters the mosquito’s gut. After an incubation period, the virus travels to the mosquito’s saliva, enabling it to infect the next person it bites. The study, published in the Journal of Royal Society Interface, utilized data from 49 previous studies on chikungunya virus in tiger mosquitoes to determine the incubation time across a range of temperatures. The findings show that infections can occur for more than six months a year in Spain, Portugal, Italy, and Greece, and for three to five months a year in Belgium, France, Germany, Switzerland, and a dozen other European countries.
Recent Outbreaks and Prevention
European outbreaks are typically initiated by infected travelers returning from tropical regions who are then bitten by local tiger mosquitoes, which subsequently spread the disease. Historically, cold European winters limited mosquito activity and curbed the spread of the virus from year to year. However, scientists are now observing year-round activity of the tiger mosquito in southern Europe, suggesting that chikungunya outbreaks are likely to become more frequent and widespread as the continent warms.
Currently, vaccines for chikungunya are available in the United States, but in Europe, treatment focuses on managing symptoms in consultation with healthcare providers. The most effective preventative measure remains avoiding mosquito bites. The World Health Organization (WHO) emphasizes that chikungunya can be devastating, with up to 40% of individuals experiencing arthritis or severe pain even five years after infection.
The Italian Society of Travel and Migration Medicine (Simvim) has recently issued guidelines for chikungunya vaccination for travelers heading to destinations like Cuba, Brazil, and parts of Asia, including India and China. Vaccination is recommended for those traveling to areas with active outbreaks, individuals at higher risk due to underlying health conditions, and those traveling to countries where local transmission has occurred within the past five years. Simvim recommends vaccination at least 14 days before potential exposure to the virus.
