Are you more sea or mountain? For the tiger mosquito, it’s both. While he was, for a long time, confined to the coast, now this damn Aedes albopictus shows up in the mountain pastures. The Pyrenees, the Cévennes, Aubrac, the Haute Vallée de l’Aude… In Occitanie, there is no longer any mountainous region that the tiger mosquito has not colonized. Of course, this particularly aggressive insect, whose period of activity starts this Monday, is not as present in these territories as in Palavas-les-Flots or Grau-du-Roi, where it bites at all costs. But, little by little, it becomes embedded in the chalets.
“Tiger mosquitoes are present everywhere, they are active throughout the region, confides Didier Jaffre, the director general of the Regional Health Agency (ARS) of Occitanie, whose fight against the tiger mosquito is a priority. They are even established in territories which, until then, were spared, in particular the mountains. In 2015, the tiger mosquito, capable of transmitting the dengue, chikungunya or zika viruses, only stung by the sea, specifically in Gard, Hérault and Pyrénées-Orientales. Four years later, he had flown to the west of the region.
A case of autochthonous dengue fever in the Hautes-Pyrénées, “it was unexpected”
Today, no department is spared by its unbearable “bzzz”. And in particular, the Hautes-Pyrénées. Last August, a resident of Andrest, a village of 1,300 souls, contracted dengue fever, a disease that can be transmitted when one is bitten by a tiger mosquito, if the insect is a carrier. A first: there had been, until then, in this department, a few cases where the disease had been imported by people who had traveled to countries at risk, in particular tropical countries. But last summer, for the first time, this patient had not frequented areas where dengue is rife. Fortunately, there were no serious consequences for this resident.
A dozen other similar cases were identified, during the year 2022, in the Pyrénées-Orientales, in Haute-Garonne and in Tarn-et-Garonne. “It was unexpected, because these are departments that had never been affected by this type of case of autochthonous dengue until then”, explains Isabelle Estève-Moussion, coordinating engineer for vector control at the ARS, in Occitania. “The presence of the tiger mosquito was, until then, quite limited in the Hautes-Pyrénées, and we thought we were spared, because of the geographical and topographical situation of the department”, adds Manon Mordelet, the departmental director of the ARS in the Hautes-Pyrenees.
“We thought that the tiger mosquito would stop below 1,000 meters”
And climate change should boost, a little more, the presence of this species in the mountains. “With higher temperatures, the tiger mosquito will go upstairs, at altitude, notes Isabelle Estève-Mousson. Until three or four years ago, we thought it would stop below 1,000 meters. But last year, we realized that he could quite do his full cycle at more than 1,500 meters. »
From now on, in the mountains, we will have to communicate, as at the seaside, on simple gestures, to fight against the tiger mosquito: empty stagnant water, which the species loves, cover, in a hermetic way, the recuperators of water, or repair broken pipes, where it takes refuge. “More particularly here, we need to raise awareness among the population a little more than elsewhere, to break the myth in which we all lived, according to which the tiger mosquito did not circulate in the department, continues Manon Mordelet. But I think last year’s episode raised awareness. »