Tests for anthrax at ABC News, where a 7-month-old boy was believed to have contracted the disease, and other media organizations in New York have come back negative.
The baby, son of an ABC producer, had visited the network's offices Sept. 28, leading investigators to believe the infection may have occurred there. Mayor Rudolph W. Giuliani said investigators had not identified the source of the infant's infection, and no suspect letter had been found.
Giuliani said the number of New Yorkers infected with the bacterium remained at four, with one case each at NBC, CBS, ABC and the New York Post.
Environmental samples from several other media outlets and schools had all yielded negative results, Giuliani said. Several results were still pending. He did not list the organizations that were tested.