Despite all the tools of modern biotechnology, there's no quick way to tell the difference between an anthrax attack and an anthrax hoax.
Medical investigators still rely on 19th-century laboratory routines - placing a suspect sample in a lab dish and seeing what grows overnight.
The lack of quick and reliable tests is a problem bedeviling public health authorities across the country amid a rash of bioterrorism scares.
"There are no test methods useful at the local level that are sensitive and specific enough for medical decision-making," said Dr. Michael Ascher, chief of the California Department of Health Services infectious disease lab.
Similarly, patients feeling flu symptoms cannot go to the doctor, get their nose swabbed for anthrax and know with certainty that a negative result means they have nothing to fear.
"A negative swab result does not rule out exposure," said Dr. Tomas Aragon, director of epidemiology and disease control for the San Francisco Department of Public Health.
Nose swab tests are tools of epidemiologists, who use them mainly to find out if an outbreak is confined to a single room, a single building or a neighborhood.
Employees of American Media Inc. in Boca Raton, Fla., lined up for nose swabs shortly after the death of photo editor Robert Stevens, but those tests - which found spores in the noses of two other employees - won't reveal whether those employees have been infected, or whether those who tested clean have nothing to fear.
Anthrax blood tests, as well, are an inexact scientific tool. A test for antibodies made in response to exposure to anthrax bacteria, they are prone to produce a small number of false positives.
"In any blood test, you might find five positives out of 1,000 for absolutely no reason," Ascher said.
National Guard units and some city disaster response teams are equipped with electronic sniffers designed to pick up an anthrax threat. But medical experts say this equipment works best only under battlefield conditions, when high concentrations of germs are suspected in the release of a cloud.
The devices cannot be relied upon to pick up small amounts of anthrax that may be present in the air, and they are also prone to report the presence of the microbe when it just isn't there.
"If it's a false sense of security, or a false alarm, it's still false," Ascher said.
Results of such tests should not be used to make medical decisions, he added.
Ascher sat on a committee that drew up a consensus report on how to detect and treat anthrax, the results of which were published in the Journal of the American Medical Association in May 1999.
A growing number of physicians are becoming wary of the drumbeat of news reports of anthrax exposure - particularly cases such as that in a Microsoft office in Reno, Nev. An envelope from Malaysia initially tested positive for anthrax, then negative, then positive again.
That's a red flag, to some researchers, that the laboratory tests health officials are relying on may either be unreliable or so sensitive they may be picking up minute contamination in the lab.
In fact, public health officials are increasingly vexed by the laboratory time spent testing benign batches of powder - yet they understand why the public is so concerned.
Unfortunately, the most reliable detector of an anthrax attack remains the first victim of such an assault. It was not a sophisticated electronic device or a simple medical test that spotted the apparent anthrax assault at American Media Inc.
Stevens' sudden illness would have almost certainly been dismissed as a rare attack of meningitis, but his doctor was suspicious because of the Sept. 11 attacks. He ordered further tests of the cloudy spinal fluid extracted from his patient and uncovered the first case of inhalational anthrax seen in the United States since 1978.
(Distributed by Scripps Howard News Service.)