State	Encephalitis/Meningitis	Fever	Clinical/Unspecified	Total	Fatalities
Alabama	34	15	0	49	3
Arkansas	32	11	0	43	3
California	1	0	0	1	0
Colorado	6	8	0	14	0
Connecticut	10	6	1	17	0
Delaware	0	1	0	1	0
District of Columbia	14	19	1	34	1
Florida	28	0	0	28	2
Georgia	28	15	1	44	7
Illinois	553	328	3	884	64
Indiana	180	102	11	293	11
Iowa	27	27	0	54	2
Kansas	22	0	0	22	0
Kentucky	53	22	0	75	5
Louisiana	204	122	3	329	25
Maryland	22	14	0	36	7
Massachusetts	19	4	0	23	3
Michigan	557	54	3	614	51
Minnesota	16	32	0	48	0
Mississippi	162	29	1	192	12
Missouri	126	42	0	168	7
Montana	2	0	0	2	0
Nebraska	84	53	15	152	7
New Jersey	16	8	0	24	0
New York	68	12	2	82	5
North Carolina	2	0	0	2	0
North Dakota	3	11	3	17	2
Ohio	310	131	0	441	31
Oklahoma	16	4	1	21	2
Pennsylvania	42	20	0	62	7
Rhode Island	1	0	0	1	0
South Carolina	1	0	0	1	0
South Dakota	17	20	0	37	0
Tennessee	47	9	0	56	7
Texas	202	0	0	202	13
Vermont	0	1	0	1	0
Virginia	16	12	1	29	2
West Virginia	3	0	0	3	2
Wisconsin	22	26	4	52	3
Wyoming	0	2	0	2	0
Total	2946	1160	50	4156	284

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.

Total Human Cases Reported to CDC- These numbers reflect both mild and severe human disease cases occurring between January 1, 2002 through December 31, 2002 that have been reported 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 2002 virus/disease activity is posted when such cases are reported to CDC.

Of the 4156 cases, 2946 (71%) were reported as West Nile meningitis or encephalitis (neuroinvasive disease), 1160 (28%) were reported as West Nile fever (milder disease), and 50 (1%) were clinically Clinical/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.

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