First definite identification of the West Nile virus in the Western hemisphere.

This paper was immediately followed in the same issue of Science by Lanciott, R.S., Roehrig, J.T., Deubet, V. et al, "Origin of the West Nile virus responsible for an outbreak of encephalitis in the Northeastern United States," Science, 286 (1999) 2333-2337. This paper published the sequence of the genome of the virus, completely characterized it, and proved that it was identical to the sequence found in a dead goose in Israel in 1998, showing the source of the virus.

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