Climate Change Fuels Rise of Tropical Diseases in Europe
Human-driven climate change is expanding the range of invasive mosquitoes, leading to local transmission of tropical diseases like dengue and chikungunya in Europe, which were previously limited to tropical regions.
In September 2024, a dengue fever outbreak occurred in the Italian coastal city of Fano. Doctors were puzzled because none of the 199 infected patients had traveled to endemic countries; they had only visited a specific neighborhood in Fano. This marked the largest local dengue outbreak in mainland Europe.
The main culprit is the Asian tiger mosquito (Aedes albopictus), which has already established populations across Southern Europe and is gradually moving north. Unlike many mosquito species, it bites during the day as well as at night. Researchers predict that rising temperatures could allow these mosquitoes to survive year-round, making tropical diseases a permanent reality in Europe.
Climate Factors and New Risks
Tiger mosquitoes thrive at 20–30°C but can survive at around 10°C. Italian researchers have observed them active until December and reappearing in March, extending the transmission season. This longer season increases the risk that returning travelers introduce viruses, which local mosquitoes then spread.
A recent study found that tiger mosquitoes can transmit chikungunya at just 14°C, not 16°C as previously thought, meaning outbreaks could occur in most European countries and for longer periods. However, extreme heat (above 35°C) and drought reduce mosquito populations, as seen in Southern France and Spain this year.
Surveillance and Control
Experts emphasize the need for continuous mosquito and disease surveillance. An experimental release of sterile male mosquitoes in Italy reduced egg numbers, but the method is expensive. Eradication is impossible, but transmission risk can be lowered.
Europeans may need to adopt preventive measures common in tropical regions: mosquito nets, eliminating standing water, using repellents, and wearing long trousers in the evening. Meanwhile, the yellow fever mosquito (Aedes aegypti), already established in Cyprus and Madeira, was recently detected in Luxembourg.
