The tiger mosquito has emerged from hibernation. 6 new departments appear in red alert, that is 57 departments in total where this mosquito responsible for dengue and chikungunya is now established and active. 2020 card and advice from the infectiologist Stéphane Gayet.
[Mis à jour le dimanche 3 mai à 19h25] The tiger mosquito is mainly present in urban areas, in other words, it likes places inhabited by humans. In 2020, the map of its presence in France shows that its still spectacular progression, according to the Vigilance-Moustique website with 6 new departments placed on red alert, or 57 in total. Every year, it comes out of hibernation in spring, period when we find the conjunction humidity and heat. Humidity, so that the laid eggs can develop and pass from the state of larva to nymph, and the heat, so that the larva pushes its development until the adult stage of the mosquito. The tiger mosquito can transmit diseases like dengue or chikungunya. Since 2006, the tiger mosquito has spread in many departments of France. In 2019, the tiger mosquito was responsible for 400 cases of dengue in France. How to recognize it? How do you know if you’ve been stung? And how to disinfect and treat the bite?
In 2020, the tiger mosquito is present in 67 departments, i.e. almost 65% of the territory, whose 57 departments on red alert. “The map shows that the progression of the tiger mosquito is still spectacular with 6 new departments placed in red alert” announces the Vigilance-Moustique website.
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• 57 departments on red alert: Charente, Cher, Loire Atlantique, Yvelines, Deux Sèvres, Vienne join the 51 departments in which the tiger mosquito was already established and active in 2019, namely Charente-Maritime, Côted’Or, Loire, Nièvre, Puy-de-Dôme , Paris, Seine-et-Marne, Essonne, Seine-Saint-Denis, Hauts de Seine, Aisne, Hautes Alpes, Hautes Pyrénées, Ariège, Lozère, Indre, Maine et Loire, Corrèze, Val-de-Marne, Bas-Rhin , Haut-Rhin, Vendée, Saône-et-Loire, Rhône, Ain, Isère, Savoie, Alpes Hautes Provence, Var, Alpes Maritimes, Haute Corse, Corse du Sud, Drôme, Vaucluse, Bouches du Rhône, Ardèche, Gard, Hérault , Aveyron, Tarn, Aude, Pyrénées Orientales, Haute Garonne, Tarn-et-Garonne, Lot, Dordogne, Lot-et-Garonne, Gers, Gironde, Landes, Pyrénées Atlantiques.
• 10 departments now on orange alert, that is to say that the mosquito has been punctually intercepted there in the last 5 years (methodology adopted by the ECDC in its mission of monitoring invasive vector species in Europe): Allier, Doubs, Indre et Loire, Jura, Loir and Cher, Haute Loire, Oise, Haute Savoie, Yonne, Val d’Oise.
• 29 departments in yellow vigilance : these departments are the subject of an entomological watch specially dedicated to the surveillance of the tiger mosquito, without any specimen having been intercepted from time to time: Ardennes, Aube, Calvados, Cantal, Côtes d’Armor, Creuse, Eure , Eure et Loir, Finistère, Ille et Vilaine, Loiret, Manche, Marne, Haute Marne, Mayenne, Meurthe et Moselle, Meuse, Morbihan, Moselle, Nord, Orne, Pas de Calais, Haute Saône, Sarthe, Seine Maritime, Somme, Haute Vienne, Vosges, Territoire de Belfort.
The tiger mosquito, or aedes albopictus, is a mosquito originally from Asia, but which is now present in most countries of the globe. “He arrived in Europe in the 2000s, by plane, or more probably by boat, since the life of mosquitoes is linked to humidity”, explains Stéphane Gayet, infectious disease specialist at Chu de Strasbourg. “It’s called a tiger mosquito in reference to the white lines that streak its body and its black legs“, he specifies. By biting its host, the tiger mosquito can transmit diseases, fortunately rare in our country, such as:
- chikungunya
- the dengue
- the zika
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• Recognize a tiger mosquito
The tiger mosquito is very easily identifiable with the naked eye: it is recognizable by its sharp black and white stripes on the body and on the legs.
- Its wings are frankly black (without spots). “The tiger mosquito is very dark, almost black, with fine white stripes. It is from these stripes that its name comes: aedes albopictus, albo means” white “and pictus” striped “, therefore” striped with white “, explains the specialist. Even in flight, it is easy to see that the tiger mosquito is darker than the others.
- It is not very lively and is rather easy to crush in flight.
- It bites mainly at dusk and dawn. Indeed, it is more diurnal than the native mosquito: it has a more daily activity, while the native mosquito is more twilight and night “, adds the infectious disease doctor.
- It is more aggressive than other mosquitoes: “Indeed, biting mammals or humans is necessary for female mosquitoes, but it seems that tiger mosquitoes prefer humans.”
“The bite is the same as that of a mosquito “
• Size of the tiger mosquito
The tiger mosquito is smaller than the native mosquito that we have here: aedes albopictus measures only a few millimeters. The native mosquito, on the other hand, generally measures between half a centimeter and a centimeter.
“Visually, the bite is the same: you can feel a little pain, there is a little red button, it swells and itches pretty quickly, describes Stéphane Gayet. The button looks like a blisters a little flat, of 5 mm to 2 cm in diameter, according to the people. The pimple may turn red and widen if there is a bad skin reaction.
“It is always important to disinfect with an antiseptic, immediately after the bite, to limit the risk of contagion of diseases, explains the doctor. Once this is done, the bite will go away on its own.
“The tiger mosquito is a potential vector for certain viral diseases, but it does not carry them systematically, begins the specialist. The best known are Dengue, Chikungunya virus and Zika virus. He is able to transmit them from one person to another “. Concretely, the mosquito contracts the disease by biting an infected individual, then transmits it by biting another person. If he’s stung, the patient remains contagious a few hours before the onset of manifestations and during the acute phase, generally 5 days after the start demonstrations.
- The dengue is a mostly asymptomatic disease. In 25 to 60% of cases, it manifests itself by symptoms similar to those of the flu (high fever, chills, headache, myalgia, nausea, vomiting, joint pain …) associated with rashes and severe tired.
- chikungunya “>Chikungunya is most often a mild illness, which causes symptoms such as extreme tiredness and pain that can last for several weeks. In case of fever and joint pain occurring after a mosquito bite, it is best to consult your doctor.
- Zika virus disease is most often a mild illness but can sometimes cause flu-like symptoms such as headache, body aches, fatigue, but also rashes. It can also be manifested by conjunctivitis or pain behind the eyes, as well as swelling of the hands and / or feet. The fever appears low and transient.
Stéphane Gayet wishes to reassure on the case of the tiger mosquito: “Indeed, it has invaded France: it is present in more than 50 departments, for example in the southern regions, PACA, New Aquitaine, Occitanie, but also Alsace, Ile-de-France”, he begins. “But you don’t have to be alarmist, this mosquito is not necessarily dangerous: for it to transmit viral diseases, such as Dengue, chikungunya or Zika infection, it must first bite someone “one of contaminated. However, there are very few cases in France.” So you have to be vigilant, but it’s not something to be afraid of, because these mosquitoes pose a risk only in countries where there are these diseases.
If you spot tiger mosquitoes, you are asked to report them to the ARS or the prefecture, which can then launch a control plan.
“Mosquitoes need standing water, explains the infectious disease specialist. We must therefore fight against this stagnant water around houses, in gardens for example, in plant saucers, gutters, basins, tires “, lists the specialist. To prevent mosquitoes from entering homes, mosquito nets can be effective. Repellents can also be used. The World Health Organization recommends the use of skin repellents, mainly those containing DEET, IR3535 or Icaridin. On the other hand, electrical devices such as diffusers or emitters of ultrasound have a low efficiency. Lemongrass only protects for about an hour against bites and is not recommended for children under 2 years of age. You must first take the advice of your doctor or, failing that, your pharmacist, because some products are not effective and others are not recommended for pregnant women and children.
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Since there is no vaccine against chikungunya and dengue, preventing and controlling the proliferation of mosquitoes remains the only means of preventing it. In addition, in case of sudden high fever (above 38.5 ° C), severe pain in the joints, muscles and headache one to two days after a trip, it is recommended to consult a doctor. Finally, if you are going on a trip to a tropical region, it is imperative to protect yourself from mosquito bites:
- wear loose fitting clothing impregnated with insecticide,
- apply mosquito repellents,
- sleep under a mosquito net previously treated with insecticide,
- turn on the air conditioning because mosquitoes don’t like low temperatures.
* surveillance which consists in periodically capturing mosquitoes using traps placed in stations. These mosquitoes are identified and sent for analysis to the Laboratory of the Regional Health Agency.
Thanks to Stéphane Gayet, infectious disease specialist at Chu de Strasbourg.
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