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West Nile Virus Activity --- United States, January 1--November 7, 2006

This report summarizes West Nile virus (WNV) surveillance data reported to CDC through ArboNET as of 3 a.m. Mountain Standard Time, November 7, 2006. A total of 41 states and the District of Columbia had reported 3,830 cases of human WNV illness to CDC (Figure, Table).

A total of 2,093 (55%) cases for which such data were available occurred in males; median age of patients was 51 years (range: 3 months--99 years). Dates of illness onset ranged from January 6 to October 22; a total of 119 cases were fatal.

A total of 306 presumptive West Nile viremic blood donors (PVDs) have been reported to ArboNET during 2006. Of these, 42 were reported from Nebraska; 33 from Texas; 26 from Colorado; 24 from Utah; 20 from Louisiana; 15 from California; 13 each from Arizona and Oklahoma; 12 from South Dakota; 11 each from Kansas and North Dakota; 10 each from Iowa, Mississippi, and Wisconsin; seven each from Indiana and Ohio; six from Idaho; five each from Minnesota and Virginia; four each from Kentucky, Missouri, and Montana; three each from Illinois and Nevada; two from Michigan; and one each from Arkansas, Maryland, New York, Oregon, Pennsylvania, and Wyoming. Of the 306 PVDs, three persons (median age: 73 years [range: 26--74 years]) subsequently had neuroinvasive illness, two persons (median age: 45 years [range: 41--49 years]) subsequently had other illness, and 65 persons (median age: 47 years [range: 17--71 years]) subsequently had West Nile fever.

In addition, 3,214 dead corvids and 745 other dead birds with WNV infection have been reported in 42 states and New York City during 2006. WNV infections have been reported in horses in 34 states, in one squirrel in Kansas, and in two unidentified animal species in North Carolina and Wyoming. WNV seroconversions have been reported in 846 sentinel chicken flocks in 12 states (Arizona, Arkansas, California, Florida, Iowa, Montana, Nevada, North Carolina, North Dakota, Pennsylvania, Utah, and Virginia). A total of 10,759 WNV-positive mosquito pools have been reported from 38 states, the District of Columbia, and New York City.

Additional information regarding national WNV activity is available from CDC at and at


Table 1
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Figure 1
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Date last reviewed: 11/8/2006


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Morbidity and Mortality Weekly Report
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