West Nile Virus

2008 West Nile Virus Activity in the United States
(Reported to CDC as of December 16, 2008)




 Map of West Nile Virus activity

Map shows the distribution of avian, animal, or mosquito infection occurring during 2008 with number of human cases if any, by state. If West Nile virus infection is reported to CDC from any area of a state, that entire state is shaded.

Data table:
Avian, animal or mosquito WNV infections have been reported to CDC ArboNET from the following states in 2008:  Alabama, Arkansas, Arizona, California, Colorado, Connecticut, District of Columbia, Delaware, Florida, Georgia, Iowa, Idaho, Illinois, Indiana, Kentucky, Louisiana, Massachusetts, Maryland, Michigan, Minnesota, Missouri, Mississippi, Montana, North Dakota, Nebraska, New Hampshire, New Jersey, New Mexico, Nevada, New York, Ohio, Oklahoma, Oregon, Pennsylvania, Puerto Rico, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Vermont, Washington, Wisconsin, West Virginia, and Wyoming.

Human cases have been reported in Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Jersey, New Mexico, New York, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.

USGS: http://diseasemaps.usgs.gov/

For information on WNV activity in Canada please see:

http://www.phac-aspc.gc.ca/wnv-vwn/index.html
http://www.cnphi-wnv.ca/healthnet/Welcome.do




2008 West Nile Virus Activity
in the United States
(Reported to CDC as of December 16, 2008)

State
Fatalities
Alabama
11
10
0
21
0
Arizona
62
36
11
109
5
Arkansas
7
2
0
9
0
California
267
135
9
411
13
Colorado
17
78
0
95
1
Connecticut
5
2
1
8
0
Delaware
0
0
1
1
0
Florida
2
0
0
2
0
Georgia
4
3
1
8
0
Idaho
1
26
6
33
1
Illinois
11
4
4
19
1
Indiana
2
0
1
3
0
Iowa
5
1
4
10
1
Kansas
8
30
0
38
0
Kentucky
3
0
0
3
0
Louisiana
9
27
0
36
0
Maryland
7
6
1
14
0
Michigan
11
4
2
17
0
Minnesota
3
18
0
21
0
Mississippi
32
66
1
99
3
Missouri
12
7
0
19
1
Montana
0
3
2
5
0
Nebraska
5
44
0
49
0
Nevada
9
5
2
16
0
New Jersey
3
4
0
7
1
New Mexico
6
3
0
9
0
New York
31
13
0
44
6
North Dakota
2
41
0
43
0
Ohio
17
2
1
20
1
Oklahoma
2
5
0
7
0
Oregon
3
13
0
16
0
Pennsylvania
12
2
0
14
1
Rhode Island
1
0
0
1
0
South Dakota
11
28
0
39
0
Tennessee
10
7
0
17
0
Texas
38
24
0
62
1
Utah
6
18
2
26
0
Virginia
0
0
1
1
0
Washington
1
1
0
2
0
West Virginia
1
0
0
1
0
Wisconsin
3
3
1
7
1
Wyoming
0
8
0
8
0
Totals 640 679 51 1370 37

 

West Nile encephalitis and West Nile meningitis are forms of severe disease that affect a person’s nervous system. Encephalitis refers to an inflammation of the brain, meningitis is an inflammation of the membrane around the brain and the spinal cord.
Click here for further explanation of WN meningitis and/or encephalitis.

West Nile fever refers to typically less severe cases that show no evidence of neuroinvasion.
WN fever is considered a notifiable disease, however the number of cases reported
(as with all diseases) may be limited by whether persons affected seek care, whether
laboratory diagnosis is ordered and the extent to which cases are reported to health
authorities by the diagnosing physician.

Other Clinical includes persons with clinical manifestations other than WN fever, WN encephalitis or WN meningitis, such as acute flaccid paralysis. Clinical/Unspecified cases are those for which sufficient clinical information was not provided.

See the case definition (2004) for Neuroinvasive and Non-Neuroinvasive Domestic Arboviral Diseases. From the CDC Epidemiology Program Office.

Total Human Cases Reported to CDC: These numbers reflect both mild and severe human disease cases occurring between January 1, 2008 to December 31, 2008 as reported through December 16, 2008 to ArboNET by state and local health departments. ArboNET is the national, electronic surveillance system established by CDC to assist states in tracking West Nile virus and other mosquito-borne viruses. Information regarding 2008 virus/disease activity is posted when such cases are reported to CDC.

Of the 1370 cases, 640 (47%) were reported as West Nile meningitis or encephalitis (neuroinvasive disease), 679 (50%) were reported as West Nile fever (milder disease), and 51 (4%) were clinically unspecified at this time. Please refer to state health department web sites for further details regarding state case totals.

Note: The high proportion of neuroinvasive disease cases among reported cases of West Nile virus disease reflects surveillance reporting bias. Serious cases are more likely to be reported than mild cases. Also, the surveillance system is not designed to detect asymptomatic infections. Data from population-based surveys indicate that among all people who become infected with West Nile virus (including people with asymptomatic infections) less than 1% will develop severe neuroinvasive disease. See: Mostashari F, Bunning ML, Kitsutani PT, et al. Epidemic West Nile Encephalitis, New York, 1999: Results of a household-based seroepidemiological survey. Lancet 2001;358:261-264.

For other diseases transmitted by mosquitos, click here. For Mosquito Products, here.

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