Neuroinvasive Disease refers to severe disease cases, particularly West Nile meningitis and West Nile encephalitis. Click here for further explanations of neuroinvasive West Nile virus disease and West Nile fever.

West Nile fever refers to typically less severe cases that show no evidence of neuroinvasion. West Nile fever is not currently on the list of nationally notifiable diseases, and therefore it is optional whether or not state health departments report these cases to CDC.
Click here for further explanations of neuroinvasive West Nile virus disease and West Nile fever.

Other Clinical includes persons with clinical manifestations other than WN fever, WN encephalitis or WN meningitis, such as acute flaccid paralysis. 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 through October 26, 2004 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 2004 virus/disease activity is posted when such cases are reported to CDC.

Of the 2231 cases, 795 (36%) were reported as West Nile meningitis or encephalitis (neuroinvasive disease), 913 (41%) were reported as West Nile fever (milder disease), and 523 (23%) were clinically unspecified at this time. Please refer to state health department web sites for further details regarding state case totals.