health
Increase in West Nile virus cases reported in south-east France
Native cases have more than doubled compared to 2025
An increase in cases of West Nile virus has been recorded in south-east France.
Four human cases of the disease were recorded in the Var department between September 21 - 27, reports Santé publique France in its latest bulletin on mosquito-borne diseases published on September 30.
All four cases were native, meaning they relate to people who had not left France in the previous 15 days and therefore were infected in France. Cases have been recorded across the department, both in Toulon and in smaller communes.
It brings the total number of native West Nile virus cases in Var this year to 15, and 60 in the Provence-Alpes-Côte d’Azur region.
Nationally, 145 native cases have been recorded in humans, and this comes alongside a rise of equine cases, both in the Var and nationwide.
Last year, only 62 native cases were reported nationwide.
We recently reported on the case of a British man who is seriously ill in hospital in Toulouse after contracting the virus. A mosquito is thought to have bitten him while he was gardening.
In the Île-de-France region alone, three people have died of the illness.
Disease spread by native mosquitoes
West Nile virus is not spread by invasive tiger mosquitoes, as tropical diseases including Chikungunya, Dengue Fever, and Zika virus are.
It is spread by native Culex mosquitoes, and the disease is mostly transmitted between mosquitoes and birds.
Humans and horses can occasionally be infected if they are bitten by an already-infected mosquito, with both being accidental hosts.
They do not typically pass the virus on to other mosquitoes that bite them, limiting the spread, and humans cannot usually transmit the illness to other humans.
Around 80% of cases in humans are symptomless, however in the remaining 20% victims contract West Nile fever.
This illness can cause a sudden fever, headache, tiredness, muscle or body aches and sometimes a skin rash or swollen glands.
In about 1% of infections, the virus can cause meningitis or encephalitis.
Cases spread
Cases of the virus have in 2026 been recorded in seven regions – Provence-Alpes-Côte d'Azur, Occitanie, Île-de-France, Auvergne-Rhône-Alpes, Nouvelle-Aquitaine, Pays de la Loire, Centre-Val de Loire.
A total of 14 cases this year could not be tied to a specific location, and could have come from other regions.
Santé publique France highlights that 12 departments recorded their first-ever cases this year: Aude, Tarn (Occitanie), Hauts-de-Seine, Seine-et-Marne, Yvelines (Île-de-France), Drôme, Rhône, Isère (Auvergne-Rhône-Alpes), Loire-Atlantique, Maine-et-Loire, Vendée (Pays de la Loire), and Loiret (Centre-Val de Loire).
There is no single known reason why cases have spiked this year, however there is a strong chance that the intense summer period may have helped establish conditions ripe for the illness to spread.
The warm weather has prolonged the typical span of mosquito season for native Culex species, and the intense weather has often changed people’s habits, including spending more time in water to cool down (close to potential mosquito breeding grounds).
The main way to reduce the risk of contracting West Nile virus is to prevent mosquitoes from biting you, mainly by trying to remove places where mosquitoes can lay eggs near your home. Readers share their tips on reducing mosquito numbers around them here.
