West Nile virus activity—United States, September 8-14, 2004

Morbidity and Mortality Weekly Report, Sept 17, 2004

During September 8-14, a total of 195 cases of human West Nile virus (WNV) illness were reported from 26 states (Alabama, Arizona, Arkansas, California, Colorado, Florida, Georgia, Idaho, Illinois, Iowa, Kansas, Maryland, Minnesota, Missouri, Nebraska, Nevada, New Mexico, New York, North Dakota, Oklahoma, Oregon, Pennsylvania, South Dakota, Tennessee, Texas, and Wisconsin).

During 2004, a total of 39 states have reported 1,386 cases of human WNV illness to CDC through ArboNET (Table, Figure). Of these, 392 (28%) cases were reported from California, 345 (25%) from Arizona, and 225 (16%) from Colorado. A total of 764 (57%) of the 1,347 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 September 8; a total of 35 cases were fatal.

[FIGURE OMITTED]

A total of 124 presumptive West Nile viremic blood donors (PVDs) have been reported to ArboNET in 2004. Of these, 37 (30%) were reported from Arizona; 35 from California; 15 from Texas; 11 from New Mexico; five from Colorado; four from Georgia; three each from Florida and South Dakota; two each from Missouri, Oklahoma, and Wisconsin; and one each from Iowa, Louisiana, Minnesota, Nebraska, and North Dakota. Of the 124 PVDs, five persons aged 35, 50, 66, 69, and 77 years subsequently had neuroinvasive illness, and 27 persons (median age: 54 years; range: 17-73 years) subsequently had West Nile fever.

In addition, during 2004, a total of 3,946 dead corvids and 868 other dead birds with WNV inflection have been reported from 44 states and New York City. WNV infections have been reported in horses from 34 states (Alabama, Arizona, Arkansas, California, Colorado, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Michigan, Minnesota, Mississippi, Missouri, Montana, Nevada, New Jersey, New Mexico, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, 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. Four unidentified animal species with WNV infection were reported from Idaho, Illinois, Iowa, and Nevada. WNV seroconversions have been reported in 690 sentinel chicken flocks from 13 states (Alabama, Arizona, Arkansas, California, Delaware, Florida, Iowa, Louisiana, Nebraska, Nevada, Pennsylvania, South Dakota, and Utah) and in seven wild hatchling birds from Missouri and Ohio. Three seropositive sentinel horses were reported from Puerto Rico. A total of 5,248 WNV-positive mosquito pools have been reported from 32 states and New York City. Additional information about national WNV activity is available from CDC at http://www.cdc.gov/ncidod/dvbid/westnile/index.htm and at http://wesmilemaps.usgs.gov.

TABLE. Number of human cases of West Nile virus (WNV) illness,
by state--United States, 2004 *

                                                            Other
                   Neuroinvasive       West Nile         clinical/
                         disease           fever       unspecified
State                 ([dagger])     ([section])     ([paragraph])

Alabama                        9               0                 0
Arizona                      130              40               175
Arkansas                       5               6                 0
California                    95             144               153
Colorado                      32             193                 0
Connecticut                    0               1                 0
Florida                       21               6                 0
Georgia                        4               3                 1
Idaho                          0               0                 2
Illinois                      14              11                 1
Indiana                        2               0                 0
Iowa                           3               4                 2
Kansas                        15               0                 0
Kentucky                       0               3                 0
Louisiana                     30               4                 0
Maryland                       4               3                 0
Michigan                       3               0                 0
Minnesota                      8               9                 0
Mississippi                    9               7                 1
Missouri                       9               2                 3
Montana                        1               3                 0
Nebraska                       0              10                 0
Nevada                        17              12                 1
New Mexico                    18              25                 4
New York                       3               2                 0
North Carolina                 2               0                 0
North Dakota                   2              16                 0
Ohio                           2               1                 0
Oklahoma                       3               1                 0
Oregon                         0               1                 0
Pennsylvania                   2               2                 0
South Carolina                 0               1                 0
South Dakota                   5              25                 0
Tennessee                      5               1                 0
Texas                         25               8                 0
Utah                           3               2                 0
Virginia                       2               0                 1
Wisconsin                      4               3                 0
Wyoming                        2               4                 0
Total                        489             553               344

                       Total
                    reported
State              to CDC **     Deaths

Alabama                    9          0
Arizona                  345          5
Arkansas                  11          0
California               392         12
Colorado                 225          2
Connecticut                1          0
Florida                   27          1
Georgia                    8          0
Idaho                      2          0
Illinois                  26          1
Indiana                    2          0
Iowa                       9          1
Kansas                    15          0
Kentucky                   3          0
Louisiana                 34          3
Maryland                   7          0
Michigan                   3          0
Minnesota                 17          0
Mississippi               17          2
Missouri                  14          0
Montana                    4          0
Nebraska                  10          0
Nevada                    30          0
New Mexico                47          2
New York                   5          0
North Carolina             2          0
North Dakota              18          1
Ohio                       3          1
Oklahoma                   4          1
Oregon                     1          0
Pennsylvania               4          0
South Carolina             1          0
South Dakota              30          1
Tennessee                  6          0
Texas                     33          2
Utah                       5          0
Virginia                   3          0
Wisconsin                  7          0
Wyoming                    6          0
Total                  1,386         35

* As of September 14, 2004.

([dagger]) Cases with neurologic manifestations (i.e., West Nile
meningitis, West Nile encephalitis, and West Nile myelitis).

([section]) Cases with no evidence of neuroinvasion.

([paragraph]) Illnesses for which sufficient clinical information
was not provided.

** Total number of human cases of WNV illness reported to ArboNet
by state and local health departments.