Global warming. Dengue and chikungunya, soon to be commonplace diseases in Europe?

Towards a normalization? Dengue fever and chikungunya could become endemic in Europe due to global warming, which is favoring the spread of the tiger mosquito, the vector of these diseases, as well as urbanization and displacement, warns a study published in the journal Lancet Planetary Health on Thursday.

Currently, four billion people in 129 countries are at potential risk of contracting dengue or chikungunya, two diseases previously found mainly in tropical and subtropical countries and whose main vectors are Aedes aegypti, the yellow fever mosquito, and Aedes albopictus, the Asian tiger mosquito.

The northward expansion of the tiger mosquito's range is being driven by global warming: the hotter it is, the shorter its development cycle becomes, while the virus's rate of multiplication in the insect increases as a result of the temperature.

The study published Thursday analyzes, for the first time, the links between the risk of dengue and chikungunya epidemics in Europe and numerous factors, such as climate, environment, socio-economic living conditions, demographics and entomological data, over 35 years.

Although the first outbreak of the disease took more than 25 years to appear in Europe, the frequency and scale of dengue and chikungunya epidemics have only increased since 2010.

Thus, in 2024 alone, 304 cases of dengue fever were recorded, more than the 275 cases recorded in the entire 15 previous years. And indigenous outbreaks have been identified in four countries: Italy, Croatia, France, and Spain.

Almost all cases (95%) occurred between July and September, and three-quarters were located in urban or semi-urban areas, with the remaining quarter in rural areas.