Atlantico: So, what is this threat concretely?
Stéphane Gayet : The evocation of the tiger mosquito and the diseases that it can inoculate (dengue, zika, chikungunya …) are usually frightening.
What is this tiger mosquito?
It is an import mosquito that began to invade France in 2004 from Italy. It is from Southeast Asia. It is considered that the two main import routes were and continue to be transport by boat of tires as well as of bamboo. The tires receive rainwater from which they conserve a small amount that can stagnate at times long and is effective for reproduction and thus the multiplication of mosquitoes in general. The water needs of bamboo are important: bamboos for export are immersed in water and also travel by boat.
However, stagnant freshwater is the key factor in mosquitoes' proliferation: the many small water reservoirs near houses allow rapid multiplication; on the contrary, its systematic suppression is one of the main methods of control of these disease vectors.
The tiger mosquito is actually the spotted mosquito. Its Latin scientific name is Aedes albopictus: albo means white and pictus means striped. It owes its Latin name to the fact that it is black with white stripes (stripes on the abdomen and legs). It was called in the vernacular (French fluent) tiger mosquito, but interestingly this name was quickly transformed into a tiger mosquito; This change was undoubtedly the source of a particular fear. It should be noted that mosquitoes are not especially bloodspot (blood drinkers) as opposed to fleas, bedbugs, muzzles and ticks that they are not insects, but arachnids. In mosquitoes, only females sting, because they need blood for the maturation of their eggs; Meanwhile, your food varies like males that do not sting.
The spotted mosquito is slightly smaller (about 5 mm) than the native mosquito in France. Despite its small size, if we look carefully enough, we can recognize it with its black color striped white (without yellow). Unlike the native mosquito that bites mainly at dusk and at night, the spotted mosquito often stings during the day. Your sting is painful. Mosquitoes live for a maximum of one month; the female performs a series of spawning operations requiring stagnant fresh water; but eggs, especially those of the tiger mosquito, can withstand a long desiccation for weeks before hatching in the presence of water; the larvae are quickly killed by the absence of water (this is a good way to combat: emptying the reservoirs with stagnant water). The mosquito lives in the vicinity of the houses and the species of tigers (albopictus) travel a little at a distance: it is around the houses that this species reproduces and multiplies (stagnant fresh water).
What is the current geographical distribution of the tiger mosquito?
The spotted mosquito is a pest officially recognized as undesirable. It has invaded more than half of the French territory of France and is the object of a national fight. Anyone who has detected a probable tiger mosquito should report it to the regional health agency (ARS) or the National Agency for Food Safety, Environment and Labor. (ANSES); It is easy to identify him with a magnifying glass after he has been killed and his corpse is a formal proof.
For a tiger mosquito report, here is a link
The tiger mosquito is present in at least 45 departments of hexagonal France: here is their latest distribution officially established. We note that its distribution follows a positive south-north gradient, with two northern regions: Île-de-France and part of the Grand-Est region (Alsace).
What are the dangers of the presence of the tiger mosquito?
Aedes albopictus or tiger mosquito transmits – with an effectiveness that varies according to circumstances – more than twenty viruses, pathogens of the so-called tropical diseases. These diseases, such as dengue and chikungunya, have emerged in temperate countries like France and their viruses are transmitted today. In practice, the presence of the tiger mosquito in a metropolitan France territory is synonymous with risk – very low to low, but the risk is the same – transmission of the dengue virus, chikungunya and zika.
Chikungunya – which means "curved back" – causes fairly severe fever and arthralgia (joint pain), muscle pain (myalgia), headache, fatigue (asthenia) and rash (which in the vernacular is called "buttons"); this disease is not fatal but very debilitating.
Dengue fever is also called "tropical flu." In its usual form, you get very sick (high fever accompanied by headaches, nausea, vomiting, joint and muscle pain, plus a rash that evokes measles), but heals without sequelae. However, in some people, it can evolve into two serious forms: dengue hemorrhagic and then dengue with shock syndrome which is fatal.
The zika virus infection is manifested by several signs and symptoms, which evoke those of dengue or chikungunya: fever, headache, rash, asthenia, muscle and joint pain. It remains mostly benign and can last up to a week. However, in the fetus – transmission of the virus during pregnancy – the virus can cause a serious malformation, microcephaly, responsible for significant and irreversible mental retardation. In addition, this infection can also cause progressive ascending paralysis (lower limbs) and generally reversible (Guillain and Barré syndrome), but it can reach the respiratory muscles and therefore cause choking. It should be noted that the zika virus is also transmitted sexually (because it is frequently present in the sperm of infected men, but may have a mild form of infection and therefore is not recognized as such).
These three diseases should be reported to the health authorities (Regional Health Agency or ARS).
But be careful: fortunately, being bitten by a spotted mosquito does not mean – and especially in France, being hexagonal – being contaminated by one of these three viruses. Because, in addition to the very special situation in which someone is bitten in the area of an international airport or in an international port by an import tiger mosquito and is already carrying one of these three viruses, it is necessary to contracting them (virus) that the female mosquito a person with one of these three diseases, which remain infrequent in metropolitan France.
However, these diseases are very rare in hexagonal France, except for the few imported cases. The most recent data in the framework of enhanced surveillance, from May 1 to June 14, 2019: 126 cases of imported dengue fever, 40% of which were on Reunion Island; 16 cases imported from chikungunya; 1 case imported from zika; but no indigenous cases for all three diseases.
What to do to protect yourself from the tiger mosquito ?
To date, there is no vaccine against dengue, chikungunya or zika virus infection.
The tiger mosquito is easy to identify. A single sting may be sufficient to transmit one of the three viral diseases in question, but it should be remembered that the risk remains fortunately very low in hexagonal France.
All mosquitoes – including the spotted mosquito – need stagnant fresh water to breed. However, this mosquito has the peculiarity of having a small radius of action: it is necessary to fight systematically against all the reservoirs of stagnant water from our immediate environment, including small ones that we do not consider sufficient: saucers under water vessels. flowering plants, water tanks, external tires (filling them with soil, for example, is effective), basins, watering cans, very wet debris, some green waste, bulky objects in plastic or metal … It is so necessary: change the water of the plants and flowers at least once a week or, if possible, remove the saucers; replace vessel water with wet sand; verify the flow of rainwater and effluents; clean gutters, drains, gutters and drainage equipment regularly; cover the necessary water tanks with a mosquito net or a simple cloth (water tanks, tanks, tanks, etc.); cover the pools and evacuate the water from the tarps or treat the water (bleach, chlorine pebbles …). This systematic and ongoing struggle against all water reservoirs remains the best way to reduce mosquito density.
It is also necessary, of course, to protect yourself from mosquito bites by covering as much as possible a person's body and using repellents on sale in pharmacy and for which the pharmacist is capable of giving precious advice. The use of mosquito nets effectively protects during sleep.
Is it possible to eradicate it in French territory? ? How is the future vis-à-vis this new invader?
Its eradication seems impossible. This spotted mosquito has proven to adapt easily to the temperate climate while originally from Southeast Asia. This invasion of southern Europe was facilitated by global warming.
A massive fight against this tiger mosquito would be doomed and would cause serious ecological problems that are not completely predictable.
Like the Asian hornet and other insects, the spotted mosquito has become part of our French fauna and so it is. Everyone should be aware of the need to fight against stagnant fresh water and thus manage the risk of vectors (mosquito) in their immediate environment. Be careful not to fall naively into the systematic use of insecticides: it would be inefficient and toxic.
It should be remembered, however, that mosquitoes have many predators that have become rare due to environmental pollution: bats and swallows, not to mention animals that eat aquatic larvae of these mosquitoes (newts, frogs, fish, bleakers, dowels, various insects aquatic adults …): all these predators of mosquitoes and their larvae are today much less. Our Western activities and ways of life have largely contributed to the ecological imbalance that favored the establishment of the tiger mosquito, the scarcity of its predators and global warming.