THE tiger mosquito is still very present in France. Last year, theAedes albopictus – the scientific name of the insect – recognizable by its black and white stripes, had left a bad memory. As of January 1, 2023, it had colonized 71 departments, a number that has been constantly increasing since its installation in mainland France in 2004. This mosquito, which bites more in the morning and evening, had been the cause of 65 “indigenous cases” of dengue fever. , concentrated in the south of France. These cases refer to patients who have not traveled to areas where the virus is widely circulating such as the Antilles, but were bitten by a mosquito itself infected through contact with an infected traveler.
And This year, the trend looks “fairly similar”. Around forty indigenous cases have been recorded so far – but the season is not yet over – says Marie-Claire Paty, coordinator of vector-borne disease surveillance at Public Health France. France had nine “outbreaks” last year, and eight, for now, in 2023.
Dengue is a viral disease which results in high fever with, in rare cases, progression to a more serious form causing bleeding. However, deaths are very rare (around 0.01% of all cases).
The impact of global warming
Overseas, the Antilles have been in an epidemic phase since mid-August, and health authorities are monitoring profiles at risk of serious forms, particularly patients with sickle cell anemia. This epidemic has contributed to an already record number of cases of dengue imported into France – more than 1,300 so far. And for the first time, an indigenous case was recorded in Île-de-France in October, in Limeil-Brévannes (Val-de-Marne), about fifteen kilometers southeast of Paris.
These cases were previously observed in southern regions, with a climate a priori more favorable to the tiger mosquito. The northward expansion of the tiger mosquito is favored by global warming: the warmer it is, the more the mosquito’s development cycle shortens. The speed of multiplication of the virus inside the insect also increases, under the effect of temperature.
The expansion of the tiger mosquito, however, remains mainly driven by travel and human behavior. Health authorities will therefore have to be extra vigilant during the 2024 Olympic Games, which will encourage, in the height of the summer season, the mixing of populations. “This is one of the anticipated risks, we are preparing for it,” assures Dr Marie-Claire Paty.