Excruciating tropical disease can now be transmitted in most of Europe, study finds | Infectious diseases

An excruciatingly painful tropical disease called chikungunya can now be transmitted to much of Europe by mosquitoes, a study has found.

Rising temperatures due to the climate crisis mean infections are now possible for more than six months a year in Spain, Greece and other southern European countries, and for two months a year in south-east England. Scientists said ongoing global warming meant it was only a matter of time before the disease spread northwards.

The analysis is the first to fully evaluate the effect of temperature on the incubation period of the virus in the Asian tiger mosquito, which has invaded Europe in recent years. The study found the minimum temperature at which infections could occur was 2.5 degrees lower than previous, less robust estimates, representing a “quite shocking” difference, the researchers said.

Chikungunya virus was first detected in Tanzania in 1952 and was limited to tropical regions. millions of infections one year. The disease causes severe and long-lasting joint pain in young children and older adults, which can be extremely debilitating and fatal.

A small number of cases, but large-scale outbreaks, have been reported in more than 10 European countries in recent years. Hundreds of cases hit France and Italy In 2025.

Sandeep Tegar, from the UK Center for Ecology and Hydrology (UKCEH) and lead author of the study, said: “The rate of global warming in Europe is approximately twice the rate of global warming globally and the lower temperature limit for the spread of the virus is crucial, so our new predictions are quite shocking. It is only a matter of time before the disease spreads northward.”

Also from UKCEH, Dr. Steven White said: “Twenty years ago, if you had said there would be chikungunya and dengue fever in Europe, everyone would have said you were crazy: they are tropical diseases. Now everything has changed. It’s because of invasive mosquitoes and climate change. It’s really that simple.”

“We are seeing rapid change and that is our concern. Until last year, France had recorded 30-odd cases of chikungunya in the last 10 years or so. Last year the number was over 800.” The virus was carried by travelers from French overseas territories in tropical regions where there were outbreaks, including Réunion.

Asian tiger mosquito (Aedes albopictusdaybiter) is moving northwards across Europe as temperatures rise. It was detected in England but is not yet confirmed. Expensive vaccines are available for chikungunya, but the best protection is to prevent being bitten.

Dr., who leads the World Health Organization’s team on viruses transmitted by insect and tick bites. Diana Rojas Alvarez said: “This study is important because it [in Europe] “It may become more pronounced over time.” He added that chikungunya can be devastating, with up to 40 percent of people still experiencing arthritis or very severe pain five years later.

“Climate has a huge impact on this, but Europe still has a chance to control the further spread of these mosquitoes,” he said. Community education is an important tool in removing stagnant water where mosquitoes breed; Wearing long, light-colored clothing and using repellent prevents bites. Health authorities also need to establish surveillance systems, he said.

When a mosquito bites an infected person, the chikungunya virus enters his or her intestine. Then, after an incubation period, the virus is present in the mosquito’s saliva, meaning it can be transmitted to the next person it bites. However, if the incubation period is longer than the mosquito’s lifespan, the virus cannot spread.

Study, Published in the Journal of Royal Society Interfaceused data from 49 previous studies on chikungunya virus in tiger mosquitoes to determine incubation time across the entire temperature range for the first time.

The study found that the cut-off temperature for transmission was 13C-14C, meaning infections could occur for more than six months of the year in Spain, Portugal, Italy and Greece, and three to five months of the year in Belgium, France, Germany, Switzerland and a dozen other European countries. The minimum temperature was previously predicted to be 16°C-18°C, meaning there is a risk of chikungunya outbreaks in more regions and for longer periods than previously thought.

The new study provides much more detailed information about areas at risk. “Identifying specific locations and possible months of transmission will allow local authorities to decide when and where to take action,” Tegar said.

Outbreaks in Europe are triggered by infected travelers returning from the tropics being bitten by local tiger mosquitoes and subsequently spreading the disease. Until now, Europe’s cold winters have halted tiger mosquito activity and acted as a firebreak for the disease from one year to the next.

However, scientists are starting to see year-round tiger mosquito activity in southern Europe; This means that chikungunya outbreaks will increase as the continent warms. The UKCEH team is investigating this issue. “Our intuition is that we’re going to have much larger outbreaks because you don’t have that natural firebreak,” White said.

Local transmission of chikungunya has not yet been reported in the United Kingdom, but recorded 73 cases Among people who contracted the virus abroad between January and June 2025, this rate is almost three times higher than in the same period in 2024.

White said: “It is important that actions continue to prevent the tiger mosquito from becoming established in the area. [the UK] because this highly invasive species has the capacity to transmit many infections that can cause serious health problems, including chikungunya, dengue and Zika viruses.”