Dengue alert: cases explode in France, what we know about the situation

Dengue alert: cases explode in France, what we know about the situation

The tiger mosquito is now present in 70 departments and continues to penetrate metropolitan France. Update on the situation.

Winter is approaching, yet they are still present: mosquitoes and especially tiger mosquitoes. Various health authorities have recently warned of an increase in dengue cases in France. According to Public Health Franceit would be more than three times higher than the maximum recorded in 2020and the risk spread “with the occurrence of outbreaks in hitherto spared wards”.

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Dengue, chikungunya… health authorities ‘mobilised very strongly’ in face of surge in cases

What is dengue fever?

Dengue fever, also called “tropical flu”, is an infectious disease caused by an arbovirus, which is mainly transmitted by the tiger mosquito. Unlike the “classic” mosquito, this parasite is silent and bites at dawn or dusk. In addition to dengue fever, it can transmit two other diseases: 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 symptoms appear 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 symptoms, but this period is short-lived. The symptoms then get worse. The patient may then suffer from nosebleeds, conjunctival bleeding or bruising.

Dengue hemorrhagic fever 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 bleeding (gastrointestinal, skin and brain), details Why doctor.

What explains this increase in cases?

According to Expressthe main reason for this the outbreak is caused by Aedes albopictus, the tiger mosquito. In the last twenty years, it has conquered more than two-thirds of the French departments. With its black body and striped legs, this insect carries many viruses such as dengue, Zika, chikungunya and yellow fever.

Other factors may also explain the increase in contamination: resumption of travel and return of travelers from risk areas as well as favorable climate conditions for mosquito breeding with heat and rain.

“The summer we experienced, exceptional for its alternation of scorching heat and intense rain episodes, especially in the southern regions, led to a significant increase in the number of mosquitoes (…),” explained Yannick Simonin, virologist, surveillance and study lecturer. of Emerging Diseases at the University of Montpellier, Western France.

In this sense, Santé Publique France clarifies that the spread of mosquito-borne infections is strongly linked to global warming.

Which departments are most affected?

Currently, three of the five departments affected by diseases are located in the region Occitania and two in the Provence-Alpes-Côte d’Azur (Paca) region.

In Occitania, four cases were detected in the same environment, in the town of Salvetat Saint-Gilles, 20 km west of Toulouse, in the Haute-Garonne; 3 cases were reported in the commune of Andrest and 15 km away in the commune of Rabastens-de-Bigorre in the Hautes-Pyrénées; the case was detected in Perpignan in the Pyrénées-Orientales. Dengue virus has never been identified in the last two wards.

In the Paca region, the two departments affected are the Var with 7 cases detected in Fayence and especially the Alpes Maritimes with 31 cases detected in three municipalities located less than 10 km apart: Saint-Jeannet, Gattières and La Gaude, it suggests Western France.

September 16 Public Health France told us : “It is the first time that cases have appeared in Pyrénées-Orientales, Haute Pyrénées and Haute Garonne”.

67 departments colonized in 2022

As of 1 January 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, Deux -Sèvres, Dordogne, Doubs, Drôme, Essonne, Gard, Gers, Gironde, Haute-Corse, Haute-Garonne, Hautes-Alpes, Hautes-Pyrénées, Haute-Savoie, Haut-Rhin, Hauts-de-Seine, Haute-V , 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, exact Public Health France.

But should we be worried?

“We are heading towards the expansion and multiplication of these episodes, the threat will only intensify in the future,” estimates Marie-Claire Patyová from the High Council for Public Health.

“We are not safe from an epidemic in the future,” adds the SPF, recalling Italy’s 2007 and 2017 chikungunya precedents.

Vigilance remains in place, while September “is a favorable period for outbreaks”: “We are strongly mobilized”, suggests Public Health France, which recalls classic preventive gestures, starting with emptying cups of stagnant water. Noting that there is research going on to sterilize mosquitoes, and “especially at the IRD in Montpellier, work to restore vegetation to combat the heat, taking into account vector-borne diseases.”

Because dengue fever is often asymptomatic (about 70% of cases), it can go largely unnoticed. Symptoms of the disease occur between the 3rd and 14th day after a 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.

There is currently no cure 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 living in endemic areas. To qualify, they had to have been infected with dengue for the first time.

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