The minute-by-minute excitement resembled that of the recent pandemonium caused by swine flu, but with an important difference: in those first late-summer days of 1999, the cause of the outbreak was unknown. It was not until Sept. 24, after three people had died, that the culprit was identified. It was the mosquito-borne West Nile virus, and investigators grimly declared that it had never been seen in the United States.
Well, not quite. America’s first cases of West Nile were actually seen in the 1950s, on the Upper East Side of Manhattan. But these cases occurred among people with terminal cancer. And the vector was not mosquitoes but the syringe of a researcher at what is now Memorial Sloan-Kettering Cancer Center.
