Identified for the first time in 2021 and found in six places in the province of Vaud, the tiger mosquito has now – scientifically speaking – settled in the two municipalities of Bourg-en-Lavaux (Cully) and Nyon since the end of 2022. This time the health risk is very low, health officials assure.
In these two municipalities, the tiger mosquito, which appeared in Asia, met the criteria established by scientists, no longer talking about the presence, but about the installation: for this, three consecutive studies, eggs must have been counted in the same station in two years. in a row.
“This insect is one of the invasive species that benefits from climate change thanks to its remarkable ecological adaptability. It also takes advantage of human activities that provide transport in vehicles,” explain Vaud’s health officials.
Field monitoring
To prevent its establishment in the zone, the Department of Health and Social Assistance (DSAS) began surveillance in 2019 and from the summer of 2020, launched a summer public prevention campaign. These measures have made it possible to monitor its progress, intervene when reports are made, and prevent the establishment of colonies. These campaigns have now resumed.
In 2022, five Vaud municipalities participated in the monitoring campaign (Aigle, Bex, Cully, Nyon and Yverdon). They were chosen for their strategic position in areas where mosquitoes thrive, already contaminated areas, or their proximity to major highways.
During that year, tiger mosquitoes were also reported in Breverenches and Lausanne, where nesting traps were set. A total of 58 traps were distributed in the zone. Recorded every two weeks, the latter were placed in locations that would attract any females ready to spawn.
Municipal employees benefit from training and support during the season. In the event of a positive reading, immediate treatment is carried out by authorities using a biocide with targeted action, without any impact on the rest of the environment, and monitoring is increased. The 2023 monitoring will take place in the seven municipalities mentioned above.
We invite public cooperation
To prevent the proliferation of this pest, the public should cooperate. It is a question of emptying all places favorable for spawning, such as small collections of stagnant water (water cups, old tires, holes in walls, unsealed abandoned containers, water cans, etc. Mosquitoes on the national site www.moustiques-suisse.ch.
The tiger mosquito has black and white striped body and legs. It ranges from 5 to 10 mm. It bites mainly during the day and can carry diseases such as dengue fever, chikungunya or Zika. However, it only spreads these diseases by biting an already infected person. Currently, the probability of transmission from a sick person to a healthy person is very low in the zone, DSAS notes.
Extended stay in Valais
In Valais, despite the measures taken, the presence of the tiger mosquito has so far been limited to the town of Monthey, extending in 2022 throughout the entire urban area of its plains, reaching the neighboring town of Colombe-Muraz.
In the Haut-Valais, in the area of the customs station of Camson in the town of Brig, it may have been brought by trucks from the affected areas. However, none of the people have settled there, Canton said in a press release on Thursday.
The spread of the insect has been observed across Switzerland, the Forest, Nature and Landscape Service told Keystone-ATS due to favorable weather conditions for its reproduction. Participation of the population is essential: approximately 80% of breeding sites are located in private gardens, it is emphasized.
The strategy followed so far, i.e. target monitoring by installing trap devices, repeated dissemination of information, more active involvement of residents and implementation of measures as per the first report, will be intensified with traps across the region by 2023. Monitoring and control measures will also be implemented in the direction of Collombey-Muraz and Massongex.
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