http://www.cdc.gov/ncidod/dvbid/westnile/
National Center for Infectious Diseases, Centers for Disease Control and Prevention
West Nile (WN) virus has emerged in recent years in temperate regions of Europe and North America, presenting a threat to public, equine, and animal health. The most serious manifestation of WN virus infection is fatal encephalitis (inflammation of the brain) in humans and horses, as well as mortality in certain domestic and wild birds