Anthrax: What we've learned about it

One month after the anthrax scare began in Florida, authorities are no closer to knowing who sent the tainted letters. What they have learned, though, are some important things about anthrax itself, as well as hard lessons about what to do - and what not to do - during any outbreak.

On the unsettling side, they now know that such an attack is no longer just the stuff of science fiction. They also learned that anthrax can spread more easily than they thought - escaping from sealed envelopes and creating a trail of contamination that stretched all the way to Peru. More encouraging, doctors say that early treatment has proved effective.

With no new letters or cases emerging in the past week, this crisis may be past its peak. But even if more attacks materialize, the experience at least gives officials a better grounding in how they should respond in the future.

Perhaps the biggest mistake officials initially made was to underestimate how easily the anthrax might spread. They knew it would pose a serious danger if sprayed over a city from a crop duster or pumped into a building's ventilation system. But most assumed that anthrax sent through the mail would endanger only the people opening the letters (or, at most, those in the room when the letters were opened). In particular, officials believed that not enough powder could leak out of sealed envelopes to harm people - which was why they rushed to treat congressional staffers and media employees with antibiotics, but failed to take the same precautions for postal workers.

This grave miscalculation became quickly apparent when a number of Washington postal workers were diagnosed with the disease, and two later died. Not only did anthrax leak out of sealed envelopes, it seems to have stuck to equipment and other pieces of mail. The trail of tainted mail has been far-reaching, with postal facilities in New Jersey, New York, Washington, Missouri, and Indiana, among others, testing positive for anthrax. The contamination even spread abroad, via diplomatic mail pouches, to US embassies in Peru and Lithuania. Although authorities are still looking for additional sources, it's possible that this widespread contamination all originated from three letters: one sent to Sen. Tom Daschle, one sent to NBC News, and one sent to the New York Post.

So far, every diagnosed case of infection, save one, can be linked directly to the mail. The only exception is the New York hospital worker, whose death last week continues to puzzle investigators.

Officials assumed postal workers were not at risk because they relied on studies from the 1980s that suggested an individual must be exposed to at least 8,000 spores to become infected. This number has now been revised downward. Medical experts say exposure to one spore, given all the right conditions, might be enough.

Likewise, public health officials have come to question the value of relying on nasal swabs to indicate whether a person has been exposed. For one thing, the vast number of tests helped contribute to the backlog in laboratories. They also provided little useful information for doctors, since positive tests for exposure do not necessarily mean individuals will get anthrax, and negative tests do not necessarily mean they won't.

Authorities have also begun to consider whether other factors, such as an individual's health and age, might play a role. So far, all of the cases of inhaled anthrax have been among people age 47 or older, while the cases of skin anthrax, which is far less serious, largely have occurred among younger people.

One of the most encouraging lessons is that anthrax is not necessarily as deadly as many feared it to be. Particularly when diagnosed early, victims can be successfully treated. So far, two individuals diagnosed with inhalation anthrax - which officials once assumed to be almost invariably fatal - have already been released from the hospital.

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