The US has spent hundreds of millions of dollars trying to develop early warning detectors for biological attacks -- on Friday it erected some around the Pentagon -- but so far the systems are far from perfect, scientists say.
The fact that people infected with anthrax are likely to survive if they are promptly treated has reinforced the broad agreement among scientists that the best defense against a biological attack is an early warning system. But designing and building such a system has proven difficult. Current detection systems, like the devices put around the Pentagon, are bulky, expensive, slow to discern problems and prone to false warnings.
Experts say they are years away from achieving their goal -- the equivalent of a smoke detector for biological weapons. But if they could produce such a device, it could transform some threats, like anthrax, from weapons of mass destruction to scary nuisances.
Without stealth, anthrax makes for a feeble weapon. If treatment begins promptly after exposure, almost everyone exposed to anthrax survives, even those who have inhaled spores.
But in an attack, a cloud of finely milled anthrax would descend, invisible and odorless. People would eventually turn up at doctors' offices and hospitals, reporting symptoms like those of the flu. By the time the proper diagnosis was made, perhaps days later, the anthrax spores would have germinated into bacteria, the bacteria would be producing toxins and the toxins would be doing their deadly work in the body.
"Almost always it's too late," said Dr. Alan P. Zelicoff, a physician and expert on biological arms at the Sandia National Laboratory in Albuquerque, N.M.
So for a biological attack, experts agree, warning systems are crucial.
New-age smoke detector
The ideal, they say, would be something that works like a smoke detector, an inexpensive device that quietly samples the air and sounds a warning when something dangerous is found. But scientists and engineers say they are far from designing a device that can pick out deadly bacteria and viruses.
"I don't think we're anywhere near the smoke detector for bio," said Dr. Stephen S. Morse, director of the Center for Public Health Preparedness at Columbia University, who once ran a Pentagon research program on ways to detect and diagnose pathogens.
The biggest problem is differentiating between the hordes of harmless germs normally in the air from dangerous bacteria -- often their close relatives.
The military has spent millions of dollars to develop detectors. The truck-based system stationed at the Pentagon can identify four biological agents in less than 45 minutes, according to the latest annual report from the Pentagon to Congress on the status of chemical and biological defenses. Some air bases use a network of these sensors and compare their readings, to cut down on false warnings.
Another system tries to use light to detect aerosol clouds from kilometers away, but it cannot tell whether the clouds contain pathogens.
The Pentagon's inspector general last year criticized development of a new, more advanced system known as the Joint Biological Point Detection System for achieving only one of 10 critical goals. It broke down often, failed to identify lethal pathogens and sometimes gave false warnings when no danger existed.
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