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Weekly Update: West Nile Virus Activity --- United States, July 24--30, 2002

This report summarizes West Nile virus (WNV) surveillance data reported to CDC through ArboNET and verified by states and other jurisdictions as of July 30, 2002.

During the reporting week of July 24--30, a total of 24 confirmed human cases of WNV illness were reported from two states (Louisiana and Mississippi). In addition, the Texas Department of Health reported eight probable cases of arbovirus encephalitis. During the same period, WNV infections were reported in 256 dead crows, 250 other dead birds, nine horses, and 147 mosquito pools.

During 2002, a total of 36 confirmed human cases of WNV illness have been reported from Louisiana and Mississippi. Among these cases, 18 occurred among men, the median age was 57 years (range: 16--88 years), and the dates of illness onset ranged from June 10 to July 19. In addition, 629 dead crows and 564 other dead birds with WNV infection were reported from 31 states, New York City, and the District of Columbia (Figure); 45 WNV infections in horses have been reported from nine states (Florida, Illinois, Kentucky, Louisiana, Mississippi, North Dakota, South Dakota, Tennessee, and Texas). During 2002, WNV seroconversions have been reported in six sentinel chicken flocks from Florida; WNV seropositivity has been reported from two states (Indiana and Louisiana) in five wild birds that were caught and released; and 242 WNV-positive mosquito pools have been reported from 10 states (Alabama, Illinois, Indiana, Massachusetts, Mississippi, New Jersey, Ohio, Pennsylvania, Texas, and Virginia) and New York City.

Additional information about WNV activity is available at and


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