What is the Usutu virus causing the first case of autochthonous arbovirosis?

A first case of arbovirosis (viral disease generally transmitted by mosquitoes) indigenous to New Aquitaine had been confirmed by the regional health agency on October 18. The sick person, originally from the Landes, had in fact not left the metropolis in the days preceding the first symptoms, which indicated that she had contracted the disease on the spot.

The dengue virus, transmitted by the tiger mosquito, as well as the West-Nile, transmitted by the Culex mosquito, had been strongly suspected at first. But a second sample from the infected person confirmed that it was in fact an infection with the Usutu virus, indicates the ARS. This is only the second case of human infection detected in France.

First cases detected in Europe in 2009

The Usutu virus “is an emerging virus of African origin, of the genus Flavivirus”, explains the ARS. It was identified for the first time in South Africa, in Swaziland in 1959, on the edge of the Usutu river, and reported by birds in Tuscany in Italy in 1996, then in Hungary, in Switzerland, in Spain and in Germany.

In Europe, the first human cases of Usutu virus (USUV) were detected in northern Italy in 2009 in immunocompromised patients. In France, the virus has been circulating since 2015, but only one case of human infection was detected in 2016 in Hérault.

It mainly affects blackbirds, sparrows, chickadees and robins

The virus mainly circulates among birds, and its monitoring in birds is carried out by the French Office for Biodiversity (ONF). “It mainly affects blackbirds, sparrows, tits and robins, but also some birds of prey (owl, owl) or migratory birds”, specifies the ARS. It is then transmitted by the bite of mosquitoes, mainly mosquitoes of the genus Culex, also called “common mosquito”, via a classic pattern: the mosquito bites a bird carrying the virus, then a human being. “The Usutu virus is not transmitted from man to man, nor from man to mosquito” adds the ARS.

The infection is very often asymptomatic or minimally symptomatic. “As was the case for the infected person, the symptoms can be those of the flu (asthenia, headache and rash)” explains the ARS.

Several mosquito control operations

“The virus is not very pathogenic and does not present a real danger to humans, continues the regional health agency, even if very rarely and in immunocompromised people, it can cause neurological disorders (encephalitis or meningoencephalitis) . High temperatures favor the abundance of mosquitoes and their “vector competence” for the Usutu virus.

As soon as this case of arbovirosis was confirmed on October 18, several mosquito control operations were carried out in the possible places of contamination frequented by the person, i.e. four sectors in the Landes and three in Gironde, in particular at Bouscat, at Pian- Médoc and in the Cauderan district in Bordeaux.

Leave a Comment