Outbreak of West Nile-like viral encephalitis -- New York, 1999.

On October 1, 1999 the CDC reported a cluster of human encephalitis cases; prior to these cases many crows had been dying. The "sentinel event" in this outbreak was the report to the New York Health Dept. by Dr. D. Asnis of two back to back human encephalitus cases. At this time the CDC was unwilling to make a definite attribution of the cases of viral encephalitis to West Nile virus.

Digital facsimile from the CDC at this link.

(Thanks to Juan Weiss for this reference and its interpretation.)