How a tiger mosquito was tracked down in Normandy, very close to Rouen

The (bad) news came last Wednesday, March 20, in a press release from ARS Normandy, the Regional Health Agency: the tiger mosquito (Aedes albopictus), originating in Southeast Asia, is now found in Normandy, the latest metropolis to be affected by this disease . . The discovery in Bois-Guillaume, very close to Rouen (Seine-Maritime), of this insect, no larger than a eurocent coin, recognizable by its black and white stripes on its body and legs, is not accidental. The Fredon Normandie Association has been investigating for several months.

To track tiger mosquitoes in France, the National Health Agency (ANSM) has two tools: the first is a national reporting platform dedicated to individuals, and the second is entomological surveys delegated to specialized service providers during public markets. This is the case of Fredon Normandy.

Before hitting the target, the association deployed a passive surveillance program throughout the region: “We installed 90 nest traps throughout Normandy in places where there is a flow of goods and people, such as ports, airports, train stations, highways. districts and major urban centers. We pick them up once or twice a month. If we suspect eggs of tiger mosquitoes, we send them to the laboratory. In France there are two,” explains Deborah Marie, head of the department of invasive exotic species and species with health problems at Fredon Normandie.

Get rid of small cups of water

“And if the results are positive,” continues the association, “for a distance of more than 150 meters around the trap, in collaboration with ARS and the relevant municipalities, we search all water points, including gutters, flower cups or other containers, watering cans or toys left in the garden , whether in homes, businesses, associations, businesses and communities,” says Deborah Marie.

The fragile tiger mosquito is a diurnal insect: it bites only during the day, does not fly in windy conditions, moves a short distance, about 150 meters around the hatching site, and does not visit large areas of water. However, it is a carrier of diseases such as dengue, chikungunya and Zika if it itself has been infected by a carrier, animal or human.

“In 2023, on four traps positive, we didn’t find a single person,” Deborah nevertheless admits. Married. On the other hand, in Normandy, 58 reports were made on the national platform, including 34 in the Seine-Maritime: “After the latest investigations, point by point, not a single individual has been found, with the exception of a small population in several places in the Bois-Guillaume area, near from Rouen. The investigation confirmed this and the mosquito was identified. Now the task is to limit its development with the means that we have at our disposal, that is, first of all, prevention. »

“Our colleagues from the South did not succeed, the tiger mosquito will take root in Normandy, the climate there is favorable. Now the ARS needs to know where it is and check if there are any patients nearby. There is a danger in this case, but the tiger mosquito itself is not contagious. He’s just a transmitter, don’t be afraid! All you have to do is empty all water points and continue to monitor its availability. We are only at the beginning of the infection. »