The snow was deep and the sky clear when experimenters in a special car drove into a Minneapolis suburb of homes, light industry, trees, and pine foliage to release the test mist. There was very little wind, and the winter night was marked by a strong temperature inversion. Overhead, a dome of warm air trapped cool air below. Air samplers showed that the release traveled nearly a mile. The "dosage area," experimenters wrote, was "unusually large."
Until Patrick's arrival, America's hunt for living weapons had focused mainly on bacterial diseases, including anthrax, plague, and tularemia, a disease which kills one out of twenty people and leaves the rest very sick. Tularemia produced not only the usual chills, fever, and coughing of infectious disease but also skin lesions larger than those of smallpox -- ulcers up to an inch wide, their centers raw, their edges turned up in reddish mounds.
But the shortcomings of bacteria as weapons were becoming obvious. Infections acquired in attacks on cities or battlefields could be successfully treated by large doses of antibiotics -- the wonder drugs that Patrick as an industry researcher had been pioneering. That emerging fact of medical life diminished the role of bacteria as killers and cripplers for war.
Viruses were a beguiling alternative. Compared with bacteria, they were less complex and often more deadly. To Detrick scientists, their microscopic size offered a range of potential military advantages.
A single human egg is just visible to the naked eye and has a width of about one hundred microns, or millionths of a meter. Human hairs are seventy-five to one hundred microns wide and easier to see because they are long. An ordinary human cell is about ten microns wide and by definition invisible. Most bacteria are one or two microns wide. They and their cousins, such as the mycobacteria, are considered the smallest of the microscopic world's fully living things.
By contrast, viruses are hundreds of times smaller, and occasionally a thousand times. If bacteria were the size of cars and minivans, viruses would be the size of cell phones. One of the tinier ones, the yellow fever virus, is only two one-hundredths of a micron wide. The foot-and-mouth virus is smaller. Viruses are small because they lack most of life's usual parts and processes, such as metabolism and respiration. Scientists consider them barely alive, seeing them more as robots than organisms. To thrive and reproduce, they invade a cell and take over its biochemical gear, often at the expense of the host.
Over the ages, this biological intimacy has made viruses one of the most dangerous of all humanity's foes. They include the causative agents of influenza, smallpox, and Ebola, the scourge from Africa that bleeds its victims dry.
People can be powerless against them. Viruses are small enough to slip into cells, where they are safe from the assaults of the human immune system. By contrast, anthrax bacteria, lumbering giants at up to four microns wide, must battle their way into the body, with many thousands of them often needed to start an infestation.
Moreover, viruses are largely invulnerable to attack by antibiotics or other weapons of science because they are nearly indistinguishable from their human hosts. As an army reference book on germ warfare put it, viruses "may be particularly attractive" because so few treatments are available against them.
As Detrick scientists investigated such issues, they did know of one treatment that worked against viruses -- immunization. Most vaccines are made of viruses that are dead, weakened, or harmless yet biologically akin to noxious ones. When injected -- or, in some cases, swallowed -- the vaccine sends a false alarm of pending attack to the body's immune system, which then forms antibodies to fight a particular type of invader. The defensive buildup is slow. So, to ward off invaders effectively, vaccines must often be given weeks to months in advance. They seldom work right away.
Copyright © 2001 by Judith Miller, Stephen Engelberg, and William Broad.
The Kopp Sisters Return!
One of the nation's first female deputy sheriffs returns in another gripping adventure based on fact.
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