Skip Navigation LinksSkip Navigation Links
Centers for Disease Control and Prevention
Safer Healthier People
Blue White
Blue White
bottom curve
CDC Home Search Health Topics A-Z spacer spacer
Blue curve MMWR spacer

Persons using assistive technology might not be able to fully access information in this file. For assistance, please send e-mail to: Type 508 Accommodation and the title of the report in the subject line of e-mail.

West Nile Virus Activity --- United States, September 29--October 5, 2004

During September 29--October 5, a total of 81 cases of human West Nile virus (WNV) illness were reported from 18 states (Alabama, Arizona, Arkansas, California, Florida, Georgia, Illinois, Iowa, Kansas, Kentucky, Minnesota, Missouri, Ohio, Oklahoma, Pennsylvania, South Dakota, Texas, and Virginia).

During 2004, a total of 40 states have reported 1,865 cases of human WNV illness to CDC through ArboNET (Table and Figure). Of these, 583 (31%) cases were reported in California, 370 (20%) in Arizona, and 225 (12%) in Colorado. A total of 1,071 (58%) of the 1,833 cases for which such data were available occurred in males; the median age of patients was 51 years (range: 1 month--99 years). Illness onset ranged from April 23 to September 23; a total of 59 cases were fatal.

A total of 177 presumptive West Nile viremic blood donors (PVDs) have been reported to ArboNET in 2004. Of these, 70 (40%) were reported in California; 37 (21%) in Arizona; 15 in Texas; 12 in New Mexico; five each in Colorado, Louisiana, and Nevada; four each in Georgia and Oklahoma; three each in Florida and South Dakota; two each in Minnesota, Missouri, and Wisconsin; and one each in Delaware, Iowa, Michigan, Nebraska, New Jersey, North Dakota, Oregon, and Pennsylvania. Of the 177 PVDs, three persons aged 35, 69, and 77 years subsequently had neuroinvasive illness, and 36 persons (median age: 53 years; range: 17--73 years) subsequently had West Nile fever.

In addition, during 2004, a total of 4,706 dead corvids and 1,138 other dead birds with WNV infection have been reported from 45 states and New York City. WNV infections have been reported in horses in 36 states; one bat in Wisconsin; six dogs in Nevada, New Mexico, and Wisconsin; six squirrels in Arizona and Wyoming; and 13 unidentified animal species in eight states (Arizona, Idaho, Illinois, Iowa, Missouri, Nevada, New York, and South Carolina). WNV seroconversions have been reported in 964 sentinel chicken flocks in 13 states (Alabama, Arizona, Arkansas, California, Delaware, Florida, Iowa, Louisiana, Nebraska, Nevada, Pennsylvania, South Dakota, and Utah) and in 25 wild hatchling birds in Missouri and Ohio. Four seropositive sentinel horses were reported in Minnesota and Puerto Rico. A total of 6,585 WNV-positive mosquito pools have been reported in 36 states, District of Columbia, and New York City.

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


Table 1
Return to top.


Figure 1
Return to top.

Use of trade names and commercial sources is for identification only and does not imply endorsement by the U.S. Department of Health and Human Services.

References to non-CDC sites on the Internet are provided as a service to MMWR readers and do not constitute or imply endorsement of these organizations or their programs by CDC or the U.S. Department of Health and Human Services. CDC is not responsible for the content of pages found at these sites. URL addresses listed in MMWR were current as of the date of publication.

Disclaimer   All MMWR HTML versions of articles are electronic conversions from ASCII text into HTML. This conversion may have resulted in character translation or format errors in the HTML version. Users should not rely on this HTML document, but are referred to the electronic PDF version and/or the original MMWR paper copy for the official text, figures, and tables. An original paper copy of this issue can be obtained from the Superintendent of Documents, U.S. Government Printing Office (GPO), Washington, DC 20402-9371; telephone: (202) 512-1800. Contact GPO for current prices.

**Questions or messages regarding errors in formatting should be addressed to

Page converted: 10/7/2004


Safer, Healthier People

Morbidity and Mortality Weekly Report
Centers for Disease Control and Prevention
1600 Clifton Rd, MailStop E-90, Atlanta, GA 30333, U.S.A


Department of Health
and Human Services

This page last reviewed 10/7/2004