Skip directly to search Skip directly to A to Z list Skip directly to site content
CDC Home

Update: West Nile Virus Activity --- United States, 2005

This report summarizes West Nile virus (WNV) surveillance data reported to CDC through ArboNET as of 3 a.m. Mountain Daylight Time, October 18, 2005.

Forty-two states have reported 2,316 cases of human WNV illness in 2005 (Figure and Table 1). By comparison, in 2004, a total of 2,151 WNV cases had been reported as of October 19, 2004 (Table 2). A total of 1,227 (57%) of the 2,163 cases for which such data were available in 2005 occurred in males; the median age of patients was 51 years (range: 3 months--98 years). Date of illness onset ranged from January 2 to October 11; a total of 66 cases were fatal.

A total of 364 presumptive West Nile viremic blood donors (PVDs) have been reported to ArboNET during 2005. Of these, 85 were reported from California; 54 from Texas; 52 from Nebraska; 22 from Louisiana; 20 from Arizona; 19 from Kansas; 17 from Iowa; 16 from South Dakota; 11 from Oklahoma; 10 from Minnesota; nine from Illinois; five each from Michigan, New Mexico, and North Dakota; four each from Alabama, Pennsylvania, and Utah; three each from Nevada and Wisconsin; two each from Colorado, Indiana, Mississippi, Montana, and Ohio; and one each from Idaho, Kentucky, Missouri, New York, North Carolina, and Oregon. Of the 364 PVDs, three persons aged 53, 56, and 72 years subsequently had neuroinvasive illness, seven persons (median age: 41 years; range: 17--64 years) subsequently had other illnesses, and 76 persons (median age: 46 years; range: 17--78 years) subsequently had West Nile fever.

In addition, 3,930 dead corvids and 831 other dead birds with WNV infection have been reported from 45 states. WNV infections have been reported in horses from 30 states; five dogs from Idaho, Minnesota, and Nebraska; four squirrels from Arizona; and five unidentified animal species in four states (Arizona, Illinois, North Carolina, and Texas). WNV seroconversions have been reported in 1,150 sentinel chicken flocks from 16 states. Eight seropositive sentinel birds have been reported from Michigan. One seropositive sentinel horse was reported from Minnesota. A total of 10,561 WNV-positive mosquito pools have been reported from 41 states and the District of Columbia.

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


Return to top.
Table 1

Table 1
Return to top.
Table 2

Table 2
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.

All MMWR HTML versions of articles are electronic conversions from typeset documents. This conversion might result in character translation or format errors in the HTML version. Users are referred to the electronic PDF version ( and/or the original MMWR paper copy for printable versions of 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 The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Rd. Atlanta, GA 30333, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC–INFO
A-Z Index
  1. A
  2. B
  3. C
  4. D
  5. E
  6. F
  7. G
  8. H
  9. I
  10. J
  11. K
  12. L
  13. M
  14. N
  15. O
  16. P
  17. Q
  18. R
  19. S
  20. T
  21. U
  22. V
  23. W
  24. X
  25. Y
  26. Z
  27. #