West Nile Virus infection is an arbovirosis accidentally transmitted to humans from an aviary reservoir via an infected mosquito. Though a French surveillance network set up in 2001 reports low circulation in France, the virus is endemic in other territories. Approximately 80% of infected children remain asymptomatic, fever is seen in 20%, and very few develop a severe neurological disease in the patient's blood or spinal fluid. Treatment remains essentially symptomatic though new specific antiviral treatments and human immunization are currently being developed.