In its ballot of July 30, Public Health France reported the detection of the first indigenous case of the Western Nile virus in France in 2025. The patient is treated in the Var.
The symptoms are clear: a case of infection of the Western Nile virus has been detected in mainland France. According to the France Public Health Bulletin published this Wednesday, July 30, this is the first indigenous case of the year 2025 and it was identified in Hyères, in the Var.
This disease appeared in France in the 1960s and, for a long time, was only observed in the Mediterranean periphery. Contamination was subsequently observed on the Atlantic facade, confirming the expansion of the virus, and, in 2024, an indigenous case was reported for the first time in Gironde.
According to Public Santé France, 38 contaminations were identified in France last year. Three regions were affected: Provence-Alpes-Côte-d’Azur, Occitanie and Nouvelle-Aquitaine. Twenty-four cases were identified in the Var, nine in Hérault, three in the Gard, one in Gironde and one in the Pyrénées-Atlantiques.
According to information from the World Health Organization (WHO), this virus “is maintained in the wild by means of a cycle involving a transmission between birds and mosquitoes”.
The disease is most often transmitted to humans via the bite of these insects, which themselves contaminated by pricking an infected bird. Mosquitoes of the genus Culex, also called common mosquitoes, are considered the main vectors. The virus can also be transmitted by contact with an infected animal but it “does not transmit a man to a man, from the man to the mosquito,” said ARS Nouvelle-Aquitaine.
80% of human infections are asymptomatic
In humans, the incubation time generally varies from three to fourteen days and the infection is asymptomatic in 80% of cases. For the remaining 20%, the disease results in a “pseudo-grippal syndrome” which causes fever, pain, headache or even nausea and vomiting. An eruption can also appear.
A serious form of the disease exists and affects approximately 1 people infected out of 150, according to the WHO, or “less than 1% of cases”, supports ARS Nouvelle-Aquitaine. It “can occur at any age” but patients over 50 and/or immunocompromised are the most exposed. In this kind of case, the Western Nile Virus may cause sometimes fatal neurological damage.
There is no vaccine for humans, too, the only way to reduce the number of human infections “consists in raising awareness of populations of risk factors”. This obviously involves protecting yourself from mosquito bites but also avoiding direct contact with sick animals.
