West Nile Virus Activity --- United States, August 14--20, 2003

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This report summarizes West Nile virus (WNV) surveillance data reported to CDC through ArboNET as of 3 a.m., Mountain Daylight Time, August 20, 2003.

During the reporting week of August 14--20, a total of 322 human cases of WNV infection were reported from 21 states (Alabama, Colorado, Georgia, Iowa, Kansas, Louisiana, Maryland, Massachusetts, Minnesota, Nebraska, New Jersey, New Mexico, North Carolina, Ohio, Oklahoma, Pennsylvania, South Dakota, Tennessee, Texas, Virginia, and Wyoming), including five fatal cases from three states (Colorado, Nebraska, and Ohio). During the same period, WNV infections were reported in 1,143 dead birds, 291 horses, one dog, and 491 mosquito pools.

During 2003, a total of 715 human cases of WNV infection have been reported from Colorado (n = 263), South Dakota (n = 117), Nebraska (n = 99), Texas (n = 70), Louisiana (n = 30), Wyoming (n = 21), Pennsylvania (n = 17), Mississippi (n = 14), Minnesota (n = 12), Alabama (n = 11), Iowa (n = nine), Ohio (n = nine), New Mexico (n = eight), North Dakota (n = six), Florida (n = four), Kansas (n = four), Kentucky (n = three), Oklahoma (n = three), Georgia (n = two), North Carolina (n = two), Tennessee (n = two), Virginia (n = two), Arkansas (n = one), Maryland (n = one), Massachusetts (n = one), Missouri (n = one), New Jersey (n = one), South Carolina (n = one), and Wisconsin (n = one) (Figure). Among 692 (97%) cases for which demographic data were available, 394 (57%) occurred among men; the median age was 46 years (range: 17 months--97 years), and the dates of illness onset ranged from May 29--August 11. Of the 692 cases, 14 fatal cases were reported from Colorado (n = six), Nebraska (n = three), Alabama (n = two), Texas (n = two), and Ohio (n = one). A total of 103 presumptive WNV viremic donors have been reported from nine states (Colorado, Florida, Louisiana, Minnesota, Mississippi, Nebraska, New Mexico, South Dakota, and Texas). Of these donors, 10 had WNV fever and none had WNV meningoenciphalitis. In addition, 3,405 dead birds with WNV infection were reported from 38 states and New York City; 703 WNV infections in horses have been reported from 31 states (Alabama, Arizona, Arkansas, Colorado, Delaware, Florida, Georgia, Illinois, Iowa, Kansas, Kentucky, Maryland, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Mexico, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Wisconsin, and Wyoming), four WNV infections were reported in dogs, one infection in a squirrel, and five infections in unidentified animal species. During 2003, WNV seroconversions have been reported in 338 sentinel chicken flocks from 11 states (Colorado, Delaware, Florida, Georgia, Iowa, Louisiana, Nebraska, North Carolina, Pennsylvania, Utah, and Virginia). Louisiana and South Dakota each reported three seropositive sentinel horses. A total of 1,959 WNV-positive mosquito pools have been reported from 31 states (Arizona, Arkansas, Colorado, Connecticut, Georgia, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Jersey, New Mexico, North Dakota, Ohio, Oklahoma, Pennsylvania, South Dakota, Tennessee, Texas, Utah, Virginia, Wisconsin, and Wyoming) and New York City.

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