WASHINGTON, D.C.--Bioterrorism experts are hotly debating a preliminary report that a 1971 smallpox outbreak in the former Soviet Union was triggered by a test of a secret bioweapon. The outbreak shows that an aerosol attack with smallpox could kill, said Alan Zelicoff, a physician and smallpox expert at the Sandia National Laboratories in Albuquerque, New Mexico, at a 15 June meeting here organized by the Institute of Medicine. "I've never seen anything quite so disturbing," said Zelicoff, who worries that existing smallpox vaccines may not offer adequate protection against the strain.
The epidemic in the city of Aralsk, Kazakhstan, on the northern shore of the Aral Sea, struck 10 people, killing three. News of it didn't reach the West until a classified official account, written in the 1970s, was sent to the Monterey Institute of International Studies last year by a Kazakh scientist. The report claimed the outbreak had a natural origin. But after scrutinizing the document and interviewing two of the surviving victims by phone, Zelicoff and his Monterey Institute colleagues reached a different conclusion.
The Soviet report concluded that the first patient most likely contracted smallpox while on an excursion on the Lev Berg, an ecological research ship. She probably picked up the virus during visits to two cities where the boat docked during its voyage (see map), then brought it home to Aralsk. But smallpox's incubation period makes that theory problematic, Zelicoff argues; moreover, the young woman never disembarked at any of the ports of call. A much more plausible explanation, he says, is that she was infected when the ship passed close to Vozrozhdeniye Island, at the time a top-secret outdoor testing site for bioweapons. Zelicoff suggests that the strain was unusually infectious, because three of the 25 people who were vaccinated against smallpox and were close to a vaccinated patient got sick themselves--an unusually high percentage.
However, Donald A. Henderson, who now advises the U.S. government on bioterrorism policy, immediately questioned the idea that a test triggered the outbreak. Henderson, who led the worldwide smallpox eradication campaign, accuses Zelicoff of seeking the media spotlight with a "half-baked report." Ultraviolet light would quickly kill the virus in an aerosol cloud, he argued--and if it had somehow survived, it would have infected more than just one crew member aboard the ship. Zelicoff countered that aerosol tests would have been carried out at night to reduce UV exposure, and that the woman was particularly vulnerable because she spent much more time on deck than other crew members.
Kenneth Alibek, a former top manager at the Soviet bioweapons program who defected to the United States in 1992, backed most of Zelicoff's account in an interview with Science. But Alibek does not believe that the test involved a hitherto unknown strain but rather India-1967 (also known as India-1), a strain that the Soviets have long been suspected of using in their bioweapons program and whose DNA was sequenced in the early 1990s.
Decontamination efforts at Vozrozhdeniye Island
Alan Zelicoff's biography
Recent story about smallpox research at VECTOR and the Centers for Disease Control and Prevention (Science, 15 March, p. 2001)