THE line has been crossed. Even if those responsible for the recent anthrax mailings are caught, another attack could come without warning. So what should we do? The USPostal Service is looking at technologies that could sterilise mail, such as ultraviolet light. But terrorists could easily find another means of delivery.
Vaccinating millions of people against an attack that may never happen isn't practical. All vaccines can cause side effects, and the anthrax one doesn't give full protection against all strains.
Researchers are working on better treatments (see opposite), but at the moment antibiotics only work if given early enough. That means the key to saving lives is to detect an attack as soon as possible. But identifying anthrax isn't easy.
There are some "quick and dirty" field tests. An antibody test can give results within 15 minutes. But Bacillus anthracis is incredibly similar to its harmless and more common bacterial cousins, and it's not clear how specific the test antibodies are. That means the tests can give false positives.
It's also why the next step is usually PCR, a technique that amplifies tiny amounts of DNA. A specialised machine the size of a bread box made by Cepheid of California can now detect anthrax DNA within 30 minutes. A positive PCR result is very reliable, says Calvin Chue of the Center for Civilian Biodefense Studies at Johns Hopkins University in Baltimore.
The problem for health officials is that negative results don't prove spores were absent. Both DNA and antibody tests rely on cracking open the tough spores. But the solutions used to do this can inhibit the PCR reaction. That's why the gold standard for anthrax testing still consists of growing the bacteria in different environments. This can take days.