Viral disease causing encephalitis (brain inflammation); rarely fatal in humans. Mosquitoes carry the virus from infected birds to other birds, people, horses, and other animals. Because corvids (ravens, crows, magpies, and blue jays) are particularly susceptible to West Nile Virus, dead crows found in or near urban areas are often used as an indicator of the spread of this disease. The list of bird species that the virus has reported in is at
http://www.cdc.gov/ncidod/dvbid/westnile/birdspecies.htm