Escalating human exposure to tropical mosquito-borne viruses in Europe

Human-induced climate change has multiple public health impacts, including the expansion of the geographical range of vector-borne diseases. Pathogens such as dengue, chikungunya and Zika viruses, transmitted by Aedes mosquitos, can cause severe health outcomes ranging from acute febrile illness, chronic joint pain, to birth defects and even death. Evaluating the future risk of human population exposure is therefore crucial as large outbreaks could overwhelm healthcare systems. Europe, one of the fastest warming regions globally, harbours the competent mosquito vector Aedes albopictus in over 20 countries, making tropical Aedes- borne viruses an increasing threat to the continent, which has already experienced local outbreaks over the past two decades. Here we use an ecological niche modelling approach to assess past, present, and future risk of human population exposure to dengue, chikungunya, and Zika viruses in Europe. Our results show that recent climate change has already increased the potential exposure to these viruses, particularly across the Mediterranean basin, which is a current hotspot for local outbreaks. Major metropolitan areas in Spain, France, Italy, and Croatia are by now located in at-risk areas, and this risk is projected to intensify and expand northward by mid-century. Under a high greenhouse gas emissions scenario, European areas ecologically suitable for Aedes -borne virus circulation could increase by up to ∼70%, leading to an additional ∼50 million people living in areas at risk by the end of the century. These findings underscore the urgent need for strengthened vector and epidemiological surveillance, as well as preparedness strategies across newly suitable regions to anticipate future public health threats associated with these arboviral diseases.