The tiger mosquito is now present in 70 departments and continues to make inroads into metropolitan France. Update on the situation.
Winter is coming, but they are still present: mosquitoes and especially the tiger mosquito. Several health authorities have recently warned of an increase in dengue cases in France. According to Public Health France, it would be more than three times higher than the maximum observed in 2020and the risk has spread “with the occurrence of outbreaks in departments hitherto safe.”
Dengue, chikungunya… the health authorities “mobilized very strongly” in the face of the increase in cases
What is dengue fever?
Also called “tropical flu”, dengue is an infectious disease caused by an arbovirus that is transmitted mainly by the tiger mosquito. Unlike the “classic” mosquito, this parasite is silent and bites at dawn or dusk. In addition to dengue, it can be a vector for two other conditions: chikungunya and zika.
There are two types of dengue: classic and hemorrhagic. In the first case, the disease is characterized by high fever, headache, nausea, vomiting, joint and muscle pain, and a measles-like rash.
These signs occur suddenly after two to seven days of incubation. A short remission is observed in the patient three to four days after the onset of the first manifestations, but this period is short-lived. The symptoms then intensify. The patient may then experience nosebleeds, conjunctival hemorrhages, or bruises.
Hemorrhagic dengue is an acute and severe form of the disease. It affects 1% of dengue cases worldwide. It can cause serious complications such as persistent fever, multiple hemorrhages (gastrointestinal, skin and brain), details Why doctor?
What explains this increase in cases?
According to The expressthe main reason for this outbreak is due to Aedes albopictus, the tiger mosquito. During the last twenty years, he has conquered more than two thirds of the French departments. With a black body and striped legs, this insect is a vector for many viruses such as dengue, Zika, chikungunya and yellow fever.
Other factors may also explain the increase in contamination: resumption of trips and return of travelers from risk areas, as well as favorable climatic conditions for the breeding of mosquitoes with heat and rain.
“The summer we are experiencing, exceptional for its alternation of scorching heat and intense episodes of rain, especially in the southern regions, caused a significant increase in the number of mosquitoes (…)”, explained Yannick Simonin, virologist, professor of surveillance and study. of emerging diseases, at the University of Montpellier, West of France.
Santé Publique France details in this regard that the spread of mosquito-borne infections is strongly associated with global warming.
Which departments are the most affected?
Currently, of the five departments affected by the disease, three are located in the region Occitania and two in the Provence-Alpes-Côte d’Azur (Paca) region.
In Occitania, four cases have been identified in the same habitat, in the town of Salvetat Saint-Gilles, 20 km west of Toulouse, in Haute-Garonne; Three cases have been reported in the municipality of Andrest and the one, 15 km away, from Rabastens-de-Bigorre, in Hautes-Pyrénées; one case was detected in Perpignan, in the Pyrénées-Orientales. The dengue virus had never been identified in these last two departments.
In the Paca region, the two affected departments are Var, with 7 cases identified in Fayence, and, above all, Alpes-Maritimes with 31 cases identified in three municipalities located less than 10 km from each other: Saint-Jeannet, Gattières and La Gaude. , indicates West of France.
On September 16, Public Health France told us: “This is the first time that cases have appeared in the Pyrénées-Orientales, Hautes-Pyrénées and Haute-Garonne.”
67 departments colonized in 2022
As of January 1, 2022, Aedes albopictus was established in 67 metropolitan departments:
Ain, Aisne, Alpes-de-Haute-Provence, Alpes-Maritimes, Ardèche, Ariège, Aude, Aveyron, Bas-Rhin, Bouches-du-Rhône, Cantal, Charente, Charente-Maritime, Cher, Corrèze, South Corsica, Côte d’Or, Two – Sèvres, Dordogne, Doubs, Drôme, Essonne, Gard, Gers, Gironde, Haute-Corse, Haute-Garonne, Hautes-Alpes, Hautes-Pyrénées, Haute-Savoie, Haut-Rhin, Hauts-de-Seine, Haute-Vienne, Hérault, Indre, Indre-et-loire, Isère, Jura, Landes, Loire, Loire Atlantique, Lot, Lot-et-Garonne, Lozère, Maine-et-Loire, Mayenne, Nièvre, Paris, Puy-de-Dôme, Pyrénées -Atlantiques, Pyrénées-Orientales, Rhône, Saône-et-Loire, Savoie, Seine-et-Marne, Seine-St-Denis, Tarn, Tarn-et-Garonne, Val-de-Marne, Var, Vaucluse, Vendée, Vienne , Yvelines, Val-d’Oise, Meurthe-et-Moselle, Loiret, precise Public Health France.
However, should we be worried?
“We are heading towards an extension and multiplication of these episodes, the threat will only intensify in the future”, estimates Marie-Claire Paty, of the Higher Council of Public Health.
“We are not, in the future, safe from an epidemic,” adds SPF, recalling the Italian precedent, in 2007 and 2017, on chikungunya.
Surveillance is still in order, while September “is a propitious period for the appearance of outbreaks”: “We are strongly mobilized”, indicates Public Health France, which recalls the classic prevention gestures, starting with emptying glasses of stagnant water. Knowing that research is being done to sterilize mosquitoes and, “particularly at the Montpellier IRD, they are working on revegetation to combat the heat, taking into account vector-borne diseases”.
Since dengue fever is usually asymptomatic (in about 70% of cases), it can go unnoticed. The manifestations of the disease occur between 3 and 14 days after the mosquito bite., with an average of 4 to 7 days. The patient usually recovers spontaneously within a few days, but significant fatigue persists for several weeks.
Currently, there is no treatment for dengue fever. There is a vaccine, developed in 2015 by the Sanofi Pasteur laboratory, but it is only intended for people aged 9 to 45 who live in endemic areas. To qualify, they must have been infected with the dengue virus for the first time.
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