The Centers for Disease Control and Prevention/Arbonet compiled a map that shows the distribution of avian, animal, or mosquito infection during 2003 with additional shading for human cases, by state. Arbonet is the national, electronic surveillance system established by CDC to assist states in tracking West Nile and other mosquito-borne viruses.
http://www.cdc.gov/ncidod/dvbid/westnile/index.htm

View the Cumulative Human map from the USGS that show all areas with positive (confirmed or probable) WNV results, but not necessarily all areas with submitted samples or no reports.

These maps reflect information gathered from the CDC and USGS
http://westnilemaps.usgs.gov/

View Arizona maps on information collected from all Arizona counties
http://www.westnileaz.com