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 1--7, 2004

During September 1--7, a total of 138 cases of human West Nile virus (WNV) illness were reported from 22 states (Alabama, Arizona, Colorado, Georgia, Illinois, Kentucky, Maryland, Michigan, Mississippi, Missouri, Nebraska, New Mexico, North Carolina, Ohio, Pennsylvania, South Carolina, South Dakota, Texas, Utah, Virginia, Wisconsin, and Wyoming).

During 2004, a total of 37 states have reported 1,191 cases of human WNV illness to CDC through ArboNET (Table, Figure). Of these, 330 (28%) cases were reported from Arizona, 326 (27%) cases were reported from California, and 195 (16%) cases were reported from Colorado. A total of 663 (57%) of the 1,163 cases for which all 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 August 29; a total of 30 cases were fatal.

A total of 98 presumptive West Nile viremic blood donors (PVDs) have been reported to ArboNET in 2004. Of these, 37 (38%) were reported from Arizona, 20 from California, 10 from Texas, nine from New Mexico, four each from Colorado and Georgia, three each from Florida and South Dakota, two each from Missouri and Wisconsin, and one each from Iowa, Louisiana, Minnesota, and Oklahoma. Of the 98 PVDs, five persons aged 35, 50, 66, 69, and 77 years subsequently had neuroinvasive illness, and 24 persons (median age: 55 years; range: 17--75 years) subsequently had West Nile fever.

In addition, during 2004, a total of 3,574 dead corvids and 749 other dead birds with WNV infection have been reported from 44 states. WNV infections have been reported in horses from 32 states (Alabama, Arizona, Arkansas, California, Colorado, Florida, Georgia, Idaho, Illinois, Iowa, Kansas, Kentucky, Michigan, Minnesota, Mississippi, Missouri, Montana, Nevada, New Jersey, New Mexico, North Carolina, Ohio, Oklahoma, Oregon, South Dakota, Tennessee, Texas, Utah, Virginia, Wisconsin, West Virginia, and Wyoming) and in five dogs from Nevada and New Mexico. Three squirrels with WNV infection were reported from Arizona. Three unidentified animal species with WNV infection were reported from Illinois, Iowa, and Nevada. WNV seroconversions have been reported in 640 sentinel chicken flocks from 13 states (Alabama, Arizona, Arkansas, California, Delaware, Florida, Iowa, Louisiana, Nebraska, Nevada, Pennsylvania, South Dakota, and Utah) and in four wild hatchling birds from Missouri and Ohio. Three seropositive sentinel horses were reported from Puerto Rico. A total of 4,657 WNV-positive mosquito pools have been reported from 32 states.

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: 9/9/2004


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 9/9/2004