Dengue case in Maine-et-Loire's La Séguinière triggers mosquito-control spraying

A resident of La Séguinière, a commune near Cholet in the Maine-et-Loire department, tested positive for dengue fever in early October 2026, according to the local outlet My-Angers.info. No information has been released about the patient's state of health.

In response, the Regional Health Agency (ARS) of Pays de la Loire planned an insecticide operation targeting the tiger mosquito population in the neighbourhood where the patient lives. The aim of such operations is to kill adult mosquitoes that may have bitten the infected person and could otherwise pass the virus on to others.

Why spraying follows a single case

Dengue does not spread directly between people. It needs a mosquito — in metropolitan France, the Asian tiger mosquito, Aedes albopictus — to bite an infected person and then bite someone else. Health authorities therefore treat a single confirmed case as a trigger for rapid vector control: identifying and spraying the places the patient recently visited to break any possible chain of transmission before it starts, a protocol ARS Pays de la Loire has applied at previous sites in the region.

The ARS used the same approach in September 2025 at Trélazé, near Angers, where spraying in the La Chevalerie neighbourhood was carried out overnight between 11 and 12 September after a resident there was diagnosed with dengue. A comparable operation was organised overnight on 18–19 September 2026 at Orvault, near Nantes, after another person tested positive, according to the news aggregator Titrespresse.

Tiger mosquito now established in most of France

The tiger mosquito has been present in La Séguinière since 2023. Across the wider Pays de la Loire region, the ARS lists 44 colonised communes in Maine-et-Loire alone, with the insect's range still expanding — new communes such as Tiercé and Mazé-Milon were added to the list in 2026.

Nationally, Aedes albopictus is now established in 83 of France's 96 mainland departments, according to figures reported by Enerzine.com. That spread creates the conditions for local, or "autochthonous," transmission whenever an infected traveller returns from a country where dengue circulates and is bitten by a local tiger mosquito.

The 2026 season so far

France recorded its first autochthonous dengue case of the 2026 season on 20 July in Carmaux, in the Tarn department, according to franceinfo's La 1ère. The regional health agency said at the time that the patient's condition was not a cause for concern.

By 7 October, Santé publique France's weekly bulletin counted six confirmed autochthonous dengue cases across four separate clusters nationwide: Carmaux (1 case) and Sète, in the Hérault department (2 cases) in Occitanie; Mouleydier, in the Dordogne (1 case), in Nouvelle-Aquitaine; and Marseille, in the Bouches-du-Rhône (2 cases), in Provence-Alpes-Côte d'Azur. The agency reported that all four of those episodes were closed, with no new clusters at that point, as summarised by Enerzine.com. The La Séguinière and Orvault cases in Pays de la Loire, reported after that bulletin, were not included in the 7 October national count.

Enhanced seasonal surveillance for dengue, chikungunya and Zika runs each year from 1 May to 30 November, the period when the tiger mosquito is active, according to Enerzine.com.

What is not yet known

Available reporting does not specify the exact date the La Séguinière spraying took place, nor how the patient contracted dengue — whether through travel or a local mosquito bite. No information on the patient's health status has been published.