Weatherwatch: climate crisis causing tropical viruses to spread

Infections such as dengue fever on rise in Europe as virus-transmitting mosquitoes expand habitats

his summer, dengue fever got a foothold in France. Traditionally this viral infection, which is spread by mosquitoes, has been confined to tropical regions including parts of Asia, the Americas and the Caribbean, but as climate warms, dengue-spreading mosquitoes are making themselves comfortable in France.

In 2010, France recorded its first locally transmitted cases of dengue – transmitted by French mosquitoes and caught by someone who hadn’t travelled to an at-risk country. Since then there have been about 12 cases of locally transmitted dengue each year, but this summer that jumped to nearly 40 cases. Meanwhile, more than 570 cases of West Nile virus – another tropical mosquito-transmitted virus – have been recorded in Europe this year, with most in Veneto, northern Italy.

“It seems that the lowlands of Veneto are emerging as an ideal habitat for the Culex mosquitoes, which can host and transmit West Nile virus,” said Michael Head, global health expert at the University of Southampton, in The Conversation.

Changing temperatures and rainfall patterns are creating new habitats and expanding the range of virus-transmitting mosquitoes. Health authorities are taking the threat seriously, with entomologists catching and testing mosquito populations to spot if they are harbouring anything new, such as malaria, yellow fever, Zika or dengue, before it starts to spread.

cover photo: Dengue, a disease transmitted by mosquitoes, has been spreading to an unprecedented level in France. Photograph: Manjunath Kiran/AFP/Getty Images