West Nile virus activity--United States, July 28-August 3, 2004.

During July 28-August 3, a total of 141 cases of human West Nile virus (WNV) illness were reported from 11 states (Alabama, Arizona, California, Colorado, Florida, Illinois, Nevada, New York, North Dakota, South Dakota, and Texas). During 2004, a total of 20 states have reported a total of 406 cases of human WNV illness to CDC through ArboNET. Of these, 247 (61%) were reported from Arizona. A total of 226 (57%) of the 406 cases occurred in males; the median age of patients was 51 years (range: 1 month-99 years). Illness onset ranged from April 20 to July 29; seven cases were fatal.