“It was to be expected”: we explain why dengue cases are increasing in the Var and the Alpes-Maritimes

An autochthonous case of dengue fever has been detected in the Alpes-Maritimes and five others have been identified in the Var, the Provence-Alpes-Côte d’Azur Regional Health Agency said in recent days.

These specific cases, caused by the bite of a tiger mosquito infected with the virus on the territory, come on top of the other cases contracted by people returning from tropical or subtropical areas. And which could be identified in Fayence in the Var or in Saint-Jeannet in the Alpes-Maritimes.

A first autochthonous case of dengue fever in France in Nice in 2010

“It’s been ten years, and the appearance in Nice in 2010 of a first case of autochthonous dengue, that there are every year, like cases of autochthonous chikungunya, also transmitted by the tiger mosquito. There are had even had small epidemics in the past, like in Nîmes”recalls Professor Pascal Del Giudice, hospital practitioner, infectiologist and dermatologist at the Fréjus Hospital Center.

For him, as for Pierre Marty, professor of parasitology and tropical medicine at the University Hospital Center and at the Faculty of Nice, such cases are not surprising. “It was to be expected. It has been 20 years since the vector that is the tiger mosquito established itself in France, arriving in Menton via Italy”they both recall, pointing to the Aedes albopictus, the tiger mosquito.

A particularly tough mosquito

So should we be worried about this multiplication of cases? This summer, this disease did not spare the south-west of the country either, where the ARS detected three autochthonous cases of dengue while the tiger mosquito was identified in 67 departments of the country.

“No, you don’t have to worry about it”. “It is a disease which is benign in 99% of cases, it is especially necessary to make the differential with malaria”reassures Professor Pierre Marty. “We must not dramatize, we must remain vigilant. We must continue the measures taken against its proliferation.”

Because the proliferation of mosquitoes is the major problem. Hence the mosquito control operations on the Mediterranean coast set up by ARS Paca “in the districts of residence of the cases” and in the places they frequented “during their period of contagiousness”.

France, future endemic area for dengue fever

“It’s a particularly tough mosquito”says Professor Del Giudice. “It reproduces in very low quantities of water, hence the need not to leave water outside at home. It has a considerable nuisance capacity: it is a mosquito that also bites during the day”.

For the two health professionals, however, it will be necessary to get used to living with this threat of dengue fever.

“What is curious is to see that this mosquito, which was not indigenous, was able to adapt so easily and quickly. We do not see any sign showing that it could leave. We see that it is there forever”. And perhaps faster than expected, continues the Var professional as global warming and mass tourism seem to be showing their consequences.

“In 1999, a Lancet study caused a sensation. This modeling predicted that southern Europe would become an endemic area for dengue in 2090. We are not there yet, there are no signs alert in our neighboring countries, but it is going faster than expected”.


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