Description: West Nile fever is a non-contagious viral disease affecting birds, horses and humans. The disease is transmitted by blood-feeding insects (mosquitoes), mainly of Culex genus, but representatives of genera Aedes, Anopheles, Coquillettidia, Culiseta, Deinocerites, Mansonia, Orthopodomyia, Psorophora and Uranotaenia may also have an important role in the spreading of the disease. Wild birds and particularly members of Corvidae, Passeridae and Charadriidae families are reservoir hosts of the infection. Mammals, including humans and equidae, are considered as Уdead-endФ or incidental hosts. The disease is characterized with fever, encephalitis, encephalomyelitis, paresis, paralysis, general weakness, prolonged recumbency, depression. West Nile fever is endemic in many regions in Africa, the Mediterranean basin and the Middle East from where the infection could be introduced into new areas by migratory birds. Due to the expanding geographical distribution of the disease, accurate and fast diagnosis becomes essential, especially in areas settled with highly susceptible human and animal populations where the virus is introduced for the first time