A first case of arbovirus (a viral disease generally transmitted by mosquitoes) indigenous to New Aquitaine was confirmed by the regional health agency on 18 October. The sick person, originally from the Landes, had not in fact left the metropolis in the days preceding the first symptoms, which indicated that he 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, were initially strongly suspected. But a second sample from the infected person confirmed that it was actually a Usutu virus infection, indicating ARS. This is only the second case of human infection found 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 first identified in South Africa, in Swaziland in 1959, on the bank of the Usutu River, and reported by birds in Tuscany in Italy in 1996, then in Hungary, Switzerland, Spain and Germany.
In Europe the first human cases of Urinary virus (USUV) were detected in northern Italy in 2009 in immunocompromised patients. In France, the virus has been around since 2015, but only one case of human infection was detected in the Hérault in 2016.
It mainly affects blackbirds, sparrows, tits and robins
The virus circulates mainly among birds and its monitoring in birds is carried out by the French Bureau for Biodiversity (ONF). “It mainly affects blackbirds, sparrows, tits and robins, but also some birds of prey (owl, owl) or migratory birds”, explains the ARS. It is then transmitted by the bite of mosquitoes, mainly mosquitoes of the genus Culex, also known as the “common mosquito”, through a classic scheme: the mosquito bites a bird carrying the virus, then a human being. “The Usutu virus is not transmitted from human to human, nor from human to mosquito” adds the ARS.
Infection is very often asymptomatic or minimally symptomatic. “As in the case of the infected person, the symptoms can be those of the flu (fatigue, headache and rash),” explains ARS.
Several mosquito control operations
“The virus is not very pathogenic and does not present a real danger to humans, continues the regional health authority, although very rarely and in immunocompromised people it can cause neurological disorders (encephalitis or meningoencephalitis). The 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, various mosquito control operations were carried out in the possible contamination places frequented by the person, i.e. four sectors in the Landes and three in Gironde, in particular in Bouscat, in Pian-Médoc and in the district of Cauderan in Bordeaux.
