As Europe braces for another long, hot summer, public health officials are sounding the alarm over a growing threat: the spread of mosquito-borne diseases typically found in tropical climates. Warmer temperatures driven by climate change and increased global travel have created ideal conditions for viruses such as dengue, chikungunya, and West Nile to gain a foothold across the continent.
According to the European Centre for Disease Prevention and Control (ECDC), locally acquired dengue infections in Europe surged to 304 cases last year—compared to just 201 cases over the previous two years combined. Italy alone accounted for 238 of those infections, marking the largest dengue outbreak ever recorded in the European Union. Meanwhile, France is currently contending with seven active chikungunya outbreaks, indicating an unusually early start to the mosquito season.
“It’s an exponential curve,” said Jan Semenza, environmental epidemiologist at Umeå University in Sweden. “Diseases like dengue and chikungunya could become endemic in Europe if trends continue.”
Dengue, which can range from mild flu-like symptoms to severe illness and death, is particularly concerning due to its ability to spread undetected. Most people infected with the virus show no symptoms or only mild ones, making it easier for transmission to occur. Chikungunya, while rarely fatal, can cause painful and long-lasting joint issues.
Recent studies suggest that it now takes less than five years for newly arrived mosquito species in Europe to spark major outbreaks—down from an estimated 25 years in the 1990s. The time window for intervention is shrinking rapidly, according to Semenza.
Globally, the situation is far worse. In 2025 alone, there have already been over three million dengue cases and 220,000 chikungunya cases reported, with more than 1,400 deaths from dengue and 80 deaths from chikungunya. Yet Europe is no longer immune. In Cyprus, health authorities have reported the reemergence of the mosquito species that transmits yellow fever—raising fears of further outbreaks.
While complete eradication of mosquitoes is unlikely, experts argue that more can be done to limit their impact. Semenza has called for enhanced surveillance in warmer European countries, especially near airports and travel hubs where infected individuals could unknowingly introduce viruses. Isolating such cases quickly could prevent local transmission.
Spain has adopted an innovative approach through a “citizen science” app that allows residents to upload mosquito photos. Using artificial intelligence, the app identifies species and alerts authorities to the presence of invasive varieties such as the Asian tiger mosquito, which can spread dengue and chikungunya. Since 2023, the app has helped detect the mosquito in over 150 municipalities.
The ECDC has also urged the public to take personal precautions, including the use of insect repellent, wearing long sleeves, and avoiding outdoor exposure at dawn and dusk. Travellers returning from dengue-endemic regions are advised to continue these measures for at least three weeks to reduce the risk of local transmission.
As the mosquito season lengthens and the risk grows, experts say European nations must draw on lessons from tropical regions long accustomed to managing these threats. “In Europe, it’s still a seasonal disease,” said Semenza. “But the season is expanding—and the cases will, too.”
