Tropical Diseases Like Dengue Fever and Chikungunya Are on the Rise in Europe
Climate change is helping invasive species to not only establish themselves across the continent but to stay alive for longer. Scientists suggest we get used to it.
Europe is experiencing a rise in tropical diseases like dengue fever and chikungunya due to climate change, with invasive mosquitoes spreading disease agents previously only associated with other continents. The Fano outbreak in 2024 was a larger incident than previous local dengue cases, with 199 detected between August and October. Researchers predict this trend will continue as so-called tropical diseases are no longer confined to tropical regions.
The main culprit is the Asian tiger mosquito (Aedes albopictus), which has established populations across Europe, particularly in southern countries. This mosquito bites during the day and night and can survive at lower temperatures than many other species. Riccardo Moretti, a senior researcher at the Italian National Agency for New Technologies, notes that the mosquito can now thrive in England's warmest parts of the year.
However, in the south, mosquito season is extending, with adults seen until December and returning in March, potentially overwintering as eggs.
Mosquito-borne diseases in Europe typically occur at the end of summer when tiger mosquitoes are most prevalent. As weather patterns change, the mosquito season may lengthen, increasing the risk of localized disease spread. If the season lasts longer, more infections could occur. A study found that tiger mosquitoes can transmit chikungunya at just 14°C (57°F), much lower than previously thought, meaning outbreaks could happen across Europe and for longer periods.
While warmer temperatures generally benefit mosquitoes, excessive heat over 35°C (95°F) can be detrimental. Southern France and Spain, affected by recent heatwaves and wildfires, may have fewer mosquitoes due to extreme heat and dryness. Rain is crucial for mosquito breeding, but excessive rain can wash away breeding sites. Humidity also plays a role in mosquito development.
Researchers emphasize the importance of ongoing surveillance to understand mosquito patterns and disease spread better. Early intervention to control mosquito populations is possible, such as releasing reproductively incompatible males to produce sterile eggs. However, completely eradicating mosquitoes is unlikely due to their efficient colonization abilities.
Instead, efforts should focus on drastically reducing transmission risks. Public health systems must be prepared to manage isolated outbreaks before they escalate into major crises.
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