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Related link: Dr. Zelicoff Comments on the Commentaries (August 26,2002)

Public Health Experts Comment on Analysis of the 1971 Smallpox Outbreak in the Soviet Union

Vozrozhdeniye Island, suspected site of smallpox biological weapons tests.

by Jonathan B. Tucker and Raymond A. Zilinskas

On July 12, 2002, the Monterey Institute's Center for Nonproliferation Studies (CNS) released the first authoritative English translation of an official Soviet report describing a previously unknown outbreak of smallpox in 1971 in the city of Aralsk, Kazakhstan. This outbreak, which sickened ten people and killed three of them, was not reported by the Soviet authorities at the time in violation of World Health Organization (WHO) regulations. The translated Soviet outbreak report is the centerpiece of CNS Occasional Paper No. 9, The 1971 Smallpox Epidemic in Aralsk, Kazakhstan, and the Soviet Biological Warfare Program, edited by Jonathan B. Tucker and Raymond A. Zilinskas.

Also included in the Occasional Paper is a retrospective epidemiological analysis of the Aralsk outbreak by Alan P. Zelicoff, M.D., a biological warfare (BW) expert at Sandia National Laboratories. Dr. Zelicoff concludes that the Aralsk epidemic originated in an open-air test of a smallpox biological weapon on Vozrozhdeniye Island, a top-secret Soviet BW testing ground in the Aral Sea. His analysis suggests that an airborne cloud of smallpox virus particles was released in the test and drifted several miles downwind of the island, where it infected a young female ichthyologist working on the deck of a research vessel that was performing an ecological survey of the Aral Sea. At the end of the voyage, she returned to her home in Aralsk and triggered the smallpox outbreak. Dr. Zelicoff also concludes that the strain of smallpox virus may have been genetically modified and formulated ("weaponized") to make it more virulent and rugged, so that it remained infectious after traveling downwind from Vozrozhdeniye Island more than nine miles. If Dr. Zelicoff's analysis is correct, it implies that the Soviets field-tested a smallpox weapon in aerosol form and that such testing resulted in civilian casualties.

Although smallpox was eradicated in 1977 by a global vaccination campaign under the auspices of the WHO, stocks of the causative virus still exist, and it is feared that they could fall into the hands of rogue states or terrorist organizations. Accordingly, it would be prudent for U.S. public health officials to take the lessons of the Aralsk outbreak into account when designing a preparedness and response program for a possible deliberate release of smallpox virus by terrorists. To stimulate informed discussion of the implications of the Aralsk smallpox outbreak for public health preparedness, including smallpox vaccination policy, the editors of the Occasional Paper invited several leading microbiologists and public health experts to comment on Dr. Zelicoff's analysis. Six commentaries were received and can be accessed by clicking on the links provided below.

Each contributor was invited to address the following questions:

1. Is Dr. Zelicoff's analysis correct in concluding that the etiology of the Aralsk smallpox outbreak was a field test of a smallpox biological weapon on Vozrozhdeniye Island?
2. Do the data presented in the Soviet report indicate that the smallpox virus strain was "weaponized" to be particularly virulent and/or vaccine-resistant?
3. Does the Aralsk outbreak and the likelihood that it resulted from a BW field test have implications for the development of a U.S. national smallpox vaccine strategy? If so, should the nation develop an alternative containment strategy to "ring vaccination" or develop a new vaccine using advanced molecular biology techniques?

Dr. Peter Jahrling, a U.S. Army medical scientist specializing in smallpox reseach, endorses Zelicoff's conclusion that the Aralsk outbreak originated in a biological weapons test on Vozrozhdeniye Island. Similarly, Dr. Sergui Popov, who once did research at Soviet BW laboratories in Obolensk and Koltsovo, finds Dr. Zelicoff's analysis consistent with the goals of the offensive Soviet BW program. Dr. Janet Gilsdorf, chair of the Department of Pediatrics and Infectious Diseases at the University of Michigan Medical Center, agrees with Dr. Zelicoff's interpretation of the data and raises concerns about the adequacy of the existing smallpox vaccine.

The other commentaries are more critical of Dr. Zelicoff's conclusions. Dr. Ronald Atlas, an environmental microbiologist and president of the American Society for Microbiology, Dr. Richard Clover, a physician specializing in family and community medicine, and Dr. D. A. Henderson, who led the World Health Organization's successful campaign to eradicate smallpox, all find Dr. Zelicoff's analysis of the cause of the Aralsk outbreak convincing but doubt his contention that the strain of the smallpox virus involved was particularly virulent or resistant. They also argue that the "ring vaccination" strategy used during the global campaign to eradicate smallpox remains the best approach should smallpox reappear, and that vaccinating the U.S. population in advance of an actual outbreak would pose more risks than benefits. Finally, Dr. Jack Woodall, the guiding force behind the ProMED reporting network on emerging infectious diseases, carefully reviews the original Soviet outbreak report and ends up differing from Dr. Zelicoff's analysis on several important points.

It is clear from the commentaries that highly capable medical scientists and epidemiologists can draw quite different interpretations from the same data set. One reason is that much about the Aralsk outbreak remains unknown, including the extent to which the smallpox virus was weaponized by the Soviet BW program, the purpose and methodology of open-air field tests on Vozrozhdeniye Island, and the efficacy of the Soviet smallpox vaccine. These questions cannot be adequately addressed until the archives of the top-secret Soviet BW program are opened, but to date the Russian government has shown no indication that it is prepared to shed light on this dark chapter of Soviet history. In the meantime, microbiologists and epidemiologists developing response plans for a future smallpox outbreak must do the best they can with the available information.

We thank Dr. W. Seth Carus for giving us the idea for these commentaries.

Related link: Dr. Zelicoff Comments on the Commentaries (August 26,2002)

Contacts for more information about the Soviet Smallpox Report: