A 75-year-old man from Saint-Sulpice-sur-Lèze, a town in the Haute-Garonne department of southern France, was hospitalized at the Purpan hospital in Toulouse after contracting West Nile virus, health officials said. His illness began on August 22, 2026, with symptoms that at first looked like flu, before tests confirmed the mosquito-borne infection, known as West Nile fever.
Purpan is a major teaching hospital that forms part of Toulouse University Hospital, one of the largest hospitals in southern France. Haute-Garonne is a department in the Occitanie region, of which Toulouse is the capital. West Nile virus spreads through mosquito bites in the same way as other infectious diseases such as Zika and chikungunya, and the Saint-Sulpice-sur-Lèze man is not an isolated case: health authorities in the department have recorded a rise in reported infections over recent weeks.
A jump from monthly to weekly cases
Jean-Sébastien Dehecq, a health engineer and entomologist at the Agence régionale de santé (ARS) Occitanie, the regional health agency, said the department normally logs about one confirmed case a month. Now, he said, it is seeing several cases a week, with infections reported in Saint-Lys, in Seysses two weeks earlier, and in Toulouse itself.
Dehecq said the agency issued a notice this week to general practitioners across the department, urging them to stay alert and to consider West Nile virus quickly if patients present with relevant symptoms.
National figures also climbing
Santé publique France, the national public health agency, reported 56 domestically acquired cases of West Nile virus infection across mainland France in its latest bulletin, published on September 6, 2026, an increase of 17 cases on the previous week. Three of those cases were in Haute-Garonne. The newspaper's report said the agency's next bulletin, due out that Wednesday, was all but certain to show a further rise.
No risk of person-to-person spread
Dehecq stressed that the virus cannot pass directly between humans. Transmission requires a Culex quinquefasciatus mosquito to bite a migratory bird carrying the virus and then bite a person or a horse, meaning humans and horses become infected only by accident. He said it was simply bad luck when a human caught it, and that such cases remain rare.
In roughly 80% of infections, the illness passes unnoticed. In other cases it causes fever, headaches or muscle pain similar to flu, and in about 1% of cases the virus leads to neurological complications.
Why cases are appearing now
According to Dehecq, mosquitoes carrying the virus generally prefer to bite migratory birds in trees rather than humans, and mostly do so at night. But in residential and urban areas, where there are more people than migratory birds, that preference may shift, which could help explain the current cluster of cases. The Culex mosquito also favors the gravel pits along the Garonne river, and current temperatures are close to ideal for its development.
Dehecq said there was no reason for alarm, since the number of severe cases reported remains low, but he called for continued vigilance so that cases can be identified and reported as quickly as possible.
Related cases and warnings
In a separate report on the same 75-year-old patient, his family said doctors did not know whether he would survive.
The World Health Organization has separately warned of a rise in West Nile virus cases across Europe.
Other cases have also been reported in the Var department, on the French Riviera.
Health authorities recorded the first human case of West Nile virus in the Nouvelle-Aquitaine region.
Further coverage has examined the symptoms, origins and transmission of the disease, which is carried by the Culex mosquito.
