Disclosures about sophisticated anthrax-based biological weapons developed by Iraq have also contributed to growing apprehension, as did the discovery that the Aum Shinrikyo cult in Japan released anthrax spores and botulinum in Tokyo nine times before it carried out its deadly 1995 subway attack with the nerve gas Sarin. The Aum's attempted germ attacks failed because the group's biologists cultured the strain of anthrax used to make vaccine, which is harmless; had they used a potent culture, the outcome might have been very different. (No one knows why the botulism attack failed.)

The Aum's lack of success in making biological weapons suggests that making a lethal device is difficult. Some specialists, such as Alan P. Zelicoff of Sandia National Laboratories, maintain that developing a system to spread anthrax or other agents so as to achieve mass fatalities is a serious challenge in its own right. Zelicoff has done experiments with simulated weapons and was unable to achieve good dispersal.

Others are less confident. Donald A. Henderson of Johns Hopkins University, who spearheaded the World Health Organization's successful campaign to eradicate smallpox, counters that widely known advances in fermentation and dispersion technology make it easier than ever for a malefactor to grow substantial quantities of some deadly agents and use them. Unlike nuclear or chemical weapons, biological weapons can be made with readily available materials or equipment. Many deadly agents, including plague and anthrax, can be found in nature. (Only two declared locations in the world hold the smallpox virus, but Henderson says he is "persuaded" that smallpox is being worked on at undeclared laboratories in Russia and possibly elsewhere.) Henderson believes 10 to 12 countries are now researching biological weapons. Moreover, thanks to domestic economic woes, Russian microbiologists are often targets for recruitment by foreign powers.

Advances in molecular biology could make engineering a superpathogen more feasible, according to Steven M. Block of Princeton University, the only molecular biologist on the panel of defense advisers known as the Jasons. Block says smallpox or anthrax engineered for extra lethality is "very credible indeed."

Most agents produce flulike symptoms in the early stages of infection, so the first victims would most likely be sent home with a diagnosis of a nonspecific viral syndrome. Only when authorities noticed unusual deaths would the alarm be raised. At that point, public demand for prophylactic medications would quickly become intense. Yet at present there are only some seven million doses of smallpox vaccine in the U.S., and scaling up production would take at least 36 months, according to Henderson. He estimates that an attack with aerosolized smallpox virus that initially infected just 100 people would within a few weeks paralyze a large part of the country: by the time the first cases had been diagnosed, people would have carried the infection to other cities.

Dozens of different agents might conceivably be employed as a weapon. Indeed, the only successful biological attack in the U.S., which was not recognized as such at the time, was with salmonella. Followers of Bhagwan Shree Rajneesh put the bacteria in salad bars in restaurants in The Dalles, Ore., in 1984, sickening several hundred people. But Henderson says anthrax, smallpox and plague represent by far the greatest threats.

The administration has proposed steep budget increases to counter biological threats against civilians. Surveillance for odd outbreaks of disease is being stepped up by 22 percent, to $86 million, regional laboratories are being established, and funds are being sought for 25 new emergency metropolitan medical teams. Research on vaccines is being boosted by $30 million, and specialized medicines are being stockpiled. The Department of Energy is working on new and better sensors and is studying airflow patterns in cities and around subways.

One focus is an attempt to prevent the spread of deadly agents with water curtains and giant balloons that would block off tunnels. Sandia scientists have also developed a noncorrosive foam that neutralizes chemical agents and effectively kills spores of a bacterium similar to anthrax. Some of the most far-out research is being funded by rapidly growing programs at the Defense Advanced Research Projects Agency (DARPA), which is researching sensitive detection devices and countermeasures that would work against a wide spectrum of agents. Many pathogens employ similar molecular mechanisms in the early stages of infection, notes Shaun B. Jones, head of DARPA's Unconventional Pathogen Countermeasures program. Many, too, share similar mechanisms of damage. Those insights make a search for broad-spectrum agents worthwhile, Jones maintains. One promising molecule for suppressing inflammation is now being tested.

DARPA is also funding projects in which red blood cells are modified. Mark Bitensky of Boston University and Ronald Taylor of the University of Virginia have shown that enzymatic complexes and antibodies can be added to the surfaces of red blood cells that give them the ability to bind pathogens. The antibodies carry the pathogens to the liver to be destroyed, and, remarkably, the lifetime of the red blood cells in the body is not affected. Maxygen in Santa Clara, Calif., is using a technique called DNA shuffling, which randomly combines potentially useful gene fragments to evolve potential DNA vaccines. James R. Baker, Jr., of the University of Michigan is developing liposomes and dendritic polymers that are safe to apply to the skin yet dissolve pathogens.

Some critics, however, maintain that high-tech may not be the best answer. The government has approached biological weapons "from the standpoint of vulnerability assessment, not threat assessment," says Jonathan B. Tucker of the Monterey Institute of International Studies. What is needed, he believes, is "a much better understanding of what might motivate a group to use these weapons" so that terrorists can be stopped before they strike. Block of Princeton likewise emphasizes the great importance of human intelligence. Civil libertarians, however, worry about giving the military any permanent counterterrorist role in the homeland.

If covert operations face difficulties, perhaps overt ones would be easier. Leonard A. Cole of Rutgers University at Newark asserts that simple moral suasion could deter many political terrorists from following the biological route, because such weapons would alienate them from their constituencies. And Barbara Hatch Rosenberg of the Federation of American Scientists argues that the U.S. could participate more constructively in the negotiations under way in Geneva aimed at strengthening the 1972 Biological and Toxin Weapons Convention. Senior officials "say the right things" about the convention, Rosenberg indicates. But she charges that the U.S. has repeatedly objected to a proposed inspection regime that would give it teeth, on the grounds that surprise visits by international inspectors might imperil commercial secrets--or compromise national security.

Some feel, moreover, that scientists themselves could do more to oppose biological terrorism. Just as physicists became active in the movement to prevent nuclear war in the past century, Block notes, "I would hope and expect biological scientists will take a leading role in anti-biological weapons activity."

--Tim Beardsley in Washington, D.C.
http://www.sciam.com/1999/0499issue/0499infocus.html