A gentle breeze blew through the town of Sverdlovsk (now Ekaterinburg), Russia, early in the morning on Monday, April 2, 1979. The inhabitants of the town suspected nothing, but the breeze carried death. A nearby bioweapons plant called Compound 19 had accidentally released anthrax, and it resulted in the largest known outbreak of inhalation anthrax in humans.

The anthrax was released after a maintenance worker at Compound 19 removed an air filter from a vent in the anthrax production facility. The filter was not replaced, so nothing prevented the release of anthrax when production resumed the next morning.

Soon after the anthrax release, at least 66 people and many more animals died. Had the wind been blowing in the opposite direction, toward the city center, the death toll would have been in the thousands. Soviet officials tried to blame the deaths on tainted black market meat, though many around the world questioned that explanation. Following the accidental release, the Soviets moved their bioweapons production facility to Stepnogorsk in Kazakhstan. There, they began producing the Alibekov strain of anthrax, which was three times more lethal than the strain released from Compound 19.

The facts about this event remained murky until after the fall of the Soviet Union in 1991. In 1992, an independent investigation by U.S. scientists confirmed that the anthrax release came from Compound 19. This investigation, other reports and defectors revealed that the USSR had been secretly developing bioweapons on a large scale, despite having signed the 1972 Biological Warfare Convention. One notable source was the former Deputy Director of the Soviet biological warfare operation, Kanatjan Alibekov (now known as Ken Alibek). Though it is believed that these bioweapons programs have ended, that cannot be verified completely.

Anthrax makes an excellent weapon because it forms spores that are nearly impossible to destroy. The spores can remain dormant for decades. They revive when they are inhaled, ingested or enter an open wound, and the bacteria spread rapidly while producing toxins. Inhalation anthrax is the deadliest form of the disease. Without treatment, about 90 percent of infected people die and with treatment, only 55 percent survive.

With the continued threat of bioweapons, it was important to identify the Soviet anthrax strain and determine if it was resistant to antibiotics, capable of evading the immune system or made the anthrax vaccine ineffective. U.S. scientists got the anthrax DNA from preserved samples of the victims’ tissues. Scientists compared the DNA sequence to the vaccine strain and found no evidence that the Soviets had altered it. This similarity suggests that Soviets avoided certain lab processes that would make the anthrax less deadly. Considering what we know now about the Soviet weapons program, it is likely that they created even more dangerous strains of genetically engineered anthrax later. The Soviets also weaponized several other bacteria including the plague bacterium, and numerous viruses including smallpox. What happened to the massive stockpiles of these deadly microbes remains uncertain, keeping many world leaders up at night while the anthrax lies dormant.

Medical Discovery News is a weekly radio and print broadcast highlighting medical and scientific breakthroughs hosted by professor emeritus Norbert Herzog and professor David Niesel, biomedical scientists at the University of Texas Medical Branch at Galveston. Learn more at www.medicaldiscoverynews.com.