If a huge plume of anthrax were let loose on a large population, what would happen? Who would survive?
Though many Americans are learning about anthrax for the first time, the Russian city of Sverdlovsk in the Ural mountains learned about the deadly bacteria through a ghastly incident in 1979.
"It is the largest recorded outbreak of inhalation anthrax in human history," said Jeanne Guillemin, a sociology professor who wrote the definitive book on the Sverdlovsk incident.
The Soviet Union was secretly manufacturing biological weapons in a place called "Compound 19," while lying about it to the world.
Apparently one night someone forgot to turn on the filtration system and a small amount of anthrax, about a third of an ounce, went up in a gust and floated out in the wind.
As the wind picked it up, it sailed like a deadly arrow across the city. And as the particles drifted on, they infected sheep and cattle as far as 30 miles away.
"When they tested this strain, it appeared to be one of the most virulent, most potent strains ever seen in Russia," said Ken Alibek, who was director of the Soviet bio-weapons program before he defected to the United States.
The anthrax strain that was released, he said, was not antibiotic-resistant, but the spores were mobilized in the deadliest possible way, exactly the size to be inhaled.
"Spores which were released were weaponized," explains Alibek.
Autopsies Reveal Anthrax
The Soviet Union was silent about the human biological battlefield, where people seemed to be dying of flu, pneumonia and internal bleeding. In the end, two-thirds of the people who would die lived a mile to 3 miles away.
Many doctors were afraid to examine the bodies for fear of contagion. But Dr. Faina Abramova, a pathologist, came out of retirement and began conducting autopsies.
While Soviet authorities were blaming tainted meat for the epidemic, she diagnosed anthrax.
"When we finished examining the bodies, we realized it was not what they were saying it was," said Lev Grinberg, then a medical student assisting Abramova.
Antiobiotics were sent out, but it was too late for many residents of the working-class neighborhood.
Spores Can Be Dormant
Thirteen years after the outbreak, and after the breakup of the Soviet Union, Matthew Meselson, a professor of molecular and cellular biology at Harvard, got permission to investigate. His team was surprised by the pattern of illness. The anthrax spores had been released from a vent on April 2, 1979. Two days later, the first two illnesses appeared. In the two weeks following, 40 more people got sick. Six more cases appeared in the third week. But amazingly, another dozen would not fall sick until more than three weeks after they were exposed. One person came down with anthrax 43 days after the spores were released.
Meselson discovered in monkey experiments that sometimes a few anthrax spores remain dormant in the lungs, in effect hidden until the body's immune system finds them.
He also found that, even though an estimated 5,000 people were exposed to anthrax in Sverdlovsk, fewer than 70 died. Most of the people who were exposed didn't even come down with anthrax or any other disease.
"Our lungs have a defense mechanism," explains Meselson. "You're inhaling millions of particles every day … And now it's kind of a war who wins."
To win, says Meselson, it helps to be young: No one under 24 came down with anthrax.
"Older people tend to be slightly more vulnerable than people who are young and robust," he says.