Bush administration officials say the anthrax strains tested in Florida, New York, and Washington appear to be the same. Federal officials briefed reporters in Washington Friday even as a seventh case of anthrax infection was reported at the New York Post newspaper.
The new homeland security chief, Tom Ridge, says the strains of anthrax mailed to media outlets in Florida and New York and to Senate Majority Leader Tom Daschle are indistinguishable from one another.
Mr. Ridge told reporters at the White House that investigators are still trying to determine the source of the anthrax spores sent through the mail.
"It may have been from the same batch. But it may have been distributed to different individuals to infect and descend into different communities," Mr. Ridge said.
Mr. Ridge also said the tests on the anthrax so far indicate it was not, in his word, "weaponized" or highly refined. So-called weapons-grade anthrax is altered to make it spread more easily through the air.
The nation's top doctor, Surgeon General David Satcher, says as dangerous as the spores are that were sent through the mail, they could have been even more lethal.
"So, a certain size of anthrax [spore] is much more efficient in terms of infecting a person than clumps of spores, if you will," he explained. "So, it means that the risk of in fact getting infection would be greater, certainly if it is aerosolized and if the sizes have been reduced that way."
Federal investigators continue to say they do not have any hard evidence that the anthrax-by-mail attacks are linked to the September 11 terrorist attacks on New York and Washington. However, The New York Times reported Friday that some law enforcement officials do suspect that the anthrax attacks are related in some way.
Meanwhile, federal health officials are moving to make available more antibiotics to counter the effects of anthrax exposure. Health and Human Services Secretary Tommy Thompson says he is working to expand the federal stockpile of antibiotics to accommodate ten to 12-million people, up from the current total of two-million doses.
"Americans should rest assured in knowing that we are responding quickly and effectively, both at the local and federal levels," Mr. Thompson said.
Also in Washington Friday, Capitol police closed off two Senate office buildings to check for anthrax spores. Several senate staffers tested positive for exposure to anthrax earlier this week after aides to Senate Majority Leader Tom Daschle opened a letter containing anthrax spores.