Anthrax tests from a pair of military mailrooms came back negative Tuesday, a day after initial tests indicated that deadly spores might have infected the mail, officials said.
Responding to what now appear to have been false alarms, officials gave antibiotics to nearly 900 postal workers and closed three mail facilities — two that serve the Pentagon and one in Washington that handles mail on its way to the military.
"We had some preliminary results that were positive but subsequent additional tests have determined that the sample that we had was in fact negative," said Dr. William Winkenwerder, assistant secretary of defense for health affairs.
He said tests that have been completed on samples from both facilities have all come back negative, though some additional tests are still incomplete.
"So on that basis we have nothing to suggest anything remotely like the events of October 2001, and we hope that with further information we'll be able to completely rule out any threat at all," he said.
In October 2001, someone sent anthrax in letters through the mail to media and government offices in Washington, Florida and elsewhere, raising fears of bioterrorism. Five people were killed and 17 more sickened.
In more than three years since the anthrax-by-mail attacks, there have been scores of initial tests that falsely reported anthrax in government mailrooms. In this case, however, the bacteria were detected separately in two mailrooms, raising concerns and invoking memories of the attacks that killed five and panicked Americans still raw from the Sept. 11 attacks.
In October 2003, two letters containing the poison ricin, sent to the Transportation Department and White House, were intercepted before they reached their destinations. The letters objected to new rules for long-haul truckers.
A small amount of ricin was discovered Feb. 2, 2004, on a mail-opening machine in the office suite of Senate Majority Leader Bill Frist, R-Tenn. The discovery led to a shutdown of three Senate office buildings for several days, and about two dozen staffers and Capitol police officers underwent decontamination.
These cases remain unsolved.