2023-07-23 13:08:35
Three cases of dengue have been identified in Alsace this week. If it is a disease of tropical origin, France and Alsace have recorded more and more cases in recent years. Here’s what you need to know about this virus.
Dengue is back in Alsace, while contaminations had already been recorded at the end of 2022 on the territory. According to the latest data communicated by the Regional Health Agency, two cases of dengue have this time been detected in Brumath and one case identified in Strasbourg. A “mosquito control” procedure was initiated in each of these areas between Wednesday and Friday: near the Schulmeister park (Neudorf) in Strasbourg, and in the neighborhood of the Arc-en-Ciel nursery school in Brumath.
But what really about this virus, which the general public in France knows as a disease from distant countries and linked to mosquitoes?
It is a virus spread by the tiger mosquito.
Dengue fever is transmitted to humans by the tiger mosquito. Originally confined to tropical regions, this species of mosquito landed in France in 2004 in Menton, in the Alpes-Maritimes. The first cases of dengue fever in Europe, however, only date back to 2010, according to the Pasteur Institute.
The virus is transmitted to humans – only by the animal, never by another human – during the “blood meal”, the name given by scientists to what feels like a bite. The beast then draws blood but can at the same time leave a strain of the virus in the human’s blood.
No symptoms in most cases
According to Public Health France, the disease is asymptomatic in the majority of cases. But it can happen to the affected individual to experience a sudden fever, nausea, vomiting, pain and skin rashes. These symptoms usually appear after 2 to 7 days of incubation.
A brief remission is generally observed after 3 to 4 days of symptoms, before the appearance of new signs: haemorrhages in the eyes, nose or bruises, before regressing rapidly after a week. Recovery then lasts 15 days.
In rare cases, dengue can become hemorrhagic and fatal (1% of cases).
No treatment but means to limit the spread
There is no no specific treatment to cure dengue fever, or vaccine in mainland France to protect against contamination. You just have to be extra vigilant when traveling in tropical areas, and use repellents, sprays or creams as much as possible.
A security perimeter will be installed in the Neuhof district • © JEAN-MARC LOOS / MAXPPP
Once a case is detected on French territory, the authorities must be reactive in order to limit the spread. The Regional Health Agency then carries out rapid mosquito control operations, but which must be limited because they are harmful to part of the biodiversity.
An increasingly widespread disease in France and around the world
With globalization and the flow of people and goods it entails, dengue fever has spread well beyond the tropics over the past twenty years. Long limited to Southeast Asia, particularly China and Thailand, the virus spread to the Indian Ocean, the South Pacific and then to the French West Indies.
Temperate zones were quickly conquered, in particular thanks to the tiger mosquito’s ability to resist low temperatures and its ability to hibernate. The first two autochthonous cases of dengue fever in France – when transmission did not occur abroad – were identified in Nice in 2010. Since then, France has reported autochthonous cases every year, with figures increasingly important in recent years : 12 in 2020, 48 in 2021 and 66 in 2022. Last year, Alsace saw 18 new towns colonized by the tiger mosquito and 7 imported cases of mosquito-borne diseases, including at least one case of dengue fever.
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