A man has been infected with the Usutu virus in New Aquitaine. This is the second case in France. What does the disease transmitted by this virus look like and what should you worry about?
On November 10, 2022, the Regional Health Agency (ARS) of Nouvelle-Aquitaine confirmed in a Press release a case of arbovirosis in a patient. This patient had not left the area in the weeks prior to symptoms. It is therefore an autochthonous case. For the record, a case is said to be autochthonous if the person contracts the disease in their usual place of residence, without having previously gone to an area where the virus circulates. After a suspicion of infection with dengue virus transmitted by the tiger mosquito, then a suspicion of infection with West-Nile transmitted by the Culex mosquito, it was confirmed that this patient was indeed infected with the Usutu virus. .
The Usutu virus, or Usuv, is a member of the Flavivirus genus and family Flaviviridae. It is an emerging virus of African origin. Its name derives from the place where it was first identified, in South Africa, Swaziland, along the Usutu River in 1959. Cases in birds were subsequently reported in Italy, Hungary, Switzerland, Spain and Germany. Human cases were described in Italy in 2009. The affected patients were immunocompromised. In France, only one human case had been detected so far, it was in 2016 in the Hérault (Occitanie region).
Symptoms of the disease and vector of contamination
Most often, Usutu virus infection is asymptomatic or minimally symptomatic. It is entirely possible that the cases went unnoticed. If there are symptoms, they may resemble those of the flu (asthenia, headache). In immunocompromised people, the disease can take a severe form with neurological disorders – encephalitis or meningoencephalitis. Encephalitis is inflammation of the brain.
The Usutu virus circulates among birds: blackbirds, sparrows, tits, robins, owls, owls, migratory birds… When a mosquito bites an infected bird, it becomes a carrier of the virus. These are ornithophilic mosquitoes of the genus Culex or common mosquito, and not tiger mosquitoes. Humans can be infected by the bite of a carrier mosquito. On the other hand, humans cannot contaminate each other or infect mosquitoes.
Prevention involves protection against mosquitoes. Mosquito control operations were carried out in New Aquitaine in the places where the person infected with the virus had gone. This involves the removal of breeding sites and nightly spraying with Adulto Killer. However, common mosquitoes are particularly abundant when temperatures are high. The drop in temperatures observed right now should naturally slow down the circulation of the virus.
