West Nile Virus Disease

West Nile virus, virus belonging to the family Flaviviridae, related to viruses that can cause yellow fever and dengue and more closely to viruses that can cause encephalitis (inflammation of the brain). Predominantly an infection of birds, West Nile virus is highly fatal for many avian species (e.g., crows and other corvids). A threat to human health occurs when infected birds are bitten by mosquitoes, which then transmit the virus to humans.