NEW YORK -- A New York hospital worker lay gravely ill with inhalation anthrax Tuesday as the widening list of victims prompted health investigators to wonder whether they have underestimated just how infectious the bacteria might be.
The hospital worker became the first person in the country outside the news media or the Postal Service to be infected with the deadliest form of the disease. A day earlier, a New Jersey woman with a skin infection became the first person in the state with no links to the Postal Service to contract anthrax.
In Washington, where the disease has killed two postal workers, officials shut down two more post offices and planned a two-week decontamination of an anthrax-tainted Senate office building. The postmaster general warned that several billion dollars would be needed to safeguard the nation's mail.
The latest victims raised the number of confirmed anthrax cases to 17 nationwide since the outbreak began in the first week of October. Ten of the victims had the inhaled form, and three have died. Seven others have less-severe skin infections.
Each development has given authorities another piece of a puzzle as they struggle to understand how the germ spreads and infects, and where it was produced. So far, there has been no indication of where the anthrax came from or who sent it.
Beyond the mail?
The latest cases raise new questions about the potential for infection beyond mail handling, though officials cautioned that no conclusions could yet be drawn.
For years, anthrax has been studied as a biological weapon with the potential to sicken tens of thousands. But those scenarios involved widespread distribution through the air, not a few letters sent through the mail.
Health officials have offered assurances that relatively large numbers of spores are needed for an inhalation infection, citing one report that estimated 8,000 to 10,000 must be inhaled. Another study estimated as few as 2,500. But exactly where the dividing line is remains unclear.
"It's what's in-between," said Dr. Bradley Perkins, an anthrax expert at the Centers for Disease Control and Prevention. "We're learning as each day goes by something about this, but unfortunately we just don't have an experience that can offer a clear-cut line."
The spread of the disease -- from mail carriers in New Jersey to congressional staffers in Washington to media employees in New York and Florida -- is giving investigators and researchers alike a painful real-world case study.
Contamination of postal facilities in Washington, New Jersey and Florida has altered investigators' assumptions about how easily the spores can be spread. Postal Service equipment and procedures, too, are under re-examination.
"It's been an eye-opener, to me at least, the amount of contamination possible from these letters," said Martin Hugh-Jones, an epidemiologist at Louisiana State University and an anthrax expert who worked on outbreaks in the former Soviet Union.
Worries about "cross-contamination" -- a piece of mail picking up spores at a mail facility and infecting someone else -- have grown with the new cases, said Dr. Anthony Fauci of the National Institutes of Health.
With these latest cases, investigators are now asking, "Did they get infected from a piece of mail that went to their home?" Fauci said Tuesday at the White House. "That is being intensively investigated right now."
One of the centers of the investigation is a mail sorting center near Trenton, N.J., that processed at least three anthrax-tainted letters sent to Sen. Tom Daschle's office in Washington, NBC anchorman Tom Brokaw and the New York Post.
Rep. Mike Pence, R-Ind., whose office was found to be contaminated last week, said he was told by investigators that the Daschle letter contained two grams of anthrax.
Dr. David Sullivan, a Johns Hopkins University expert on anthrax, said two grams of the substance could mean up to 20 billion spores, depending on the purity and the moisture content.
In New York, the latest victim worked in a hospital supply room, but Mayor Rudolph Giuliani said there was no indication she handled mail. CDC officials, however, said the hospital had recently combined its mailroom and stockroom.
The hospital was closed to patients Tuesday, and workers were taken elsewhere for testing. New York Health Commissioner Neal Cohen said other city hospitals had been told to take precautions.
"The woman is critically ill," he said. "There's evidence the inhalation anthrax has released a lot of toxins and done a lot of damage systemically, and at this point she is struggling for survival."
Officials in New Jersey were searching for a link to earlier cases. The 51-year-old accountant identified with skin anthrax on Monday does not remember opening any suspicious mail. She has been successfully treated and released from the hospital.