Editor's note: the following article was developed from a lecture given by Dr. David Walker in 1994. It is a disconcerting account of how the worst recorded outbreak of anthrax, a disease caused by Bacillus anthracsis bacteria, was handled in Russia in 1979. Dr. Walker (currently a Professor of Pathology and Chairman of the Department of Pathology at the University of Texas Medical Branch (UTMB) was intimately involved in the studies that were done after the outbreak. There is a short addendum at the end of this article.
This article recounts the chilling, yet fascinating story of the deadliest outbreak of anthrax in recorded history. Anthrax is a bacterium (germ) that can cause a serious, sometimes fatal infection. Anthrax can be used as a weapon. In 2001, anthrax was spread through the mail in a powder. Twenty-two people were infected. The events that occurred in Sverdlovsk, Russia, in 1979 demonstrate what can happen when anthrax is released into the air.
The Anthrax Outbreak
This was the ninth day of the mysterious, fatal epidemic that struck Sverdlovsk in early April of 1979. Autopsies already had been performed on 37 victims who died of an unknown disease. Yet neither the clinicians nor the pathologists had identified the cause of the epidemic. Moreover, as you can imagine, the members of the pathology department were frustrated and overburdened with work. So, on this day, Dr. Faina Abramova, who had been chief of pathology at hospital #40, returned from retirement to help perform the autopsies.
The first autopsy Dr. Abramova performed was number 38 of the 42 ultimately performed by the local pathologists. The patient was a 43-year-old man who had had weakness and fever for two days. He was admitted to the hospital where he died four days later.
At the autopsy table, Dr. Abramova was struck by the crimson color of the membranes (meninges) covering the man's brain. In her description, she referred to this covering as the "cardinal's cap" because of its color and location. Astonishingly, she recognized this finding as characteristic of anthrax infection. (Few doctors have ever seen the disease anthrax.) In fact, her diagnosis was based on her recollection of a brain specimen from a patient with anthrax on display in a museum at her medical school.
The Anthrax Outbreak Cover-up
Although the epidemic was nine days old, there had been no word from the local authorities regarding the nature of the strange illness. When word finally got out that the epidemic was due to anthrax infection, the citizens promptly suspected that the source was military compound #19. Military compound #19 was a large facility that included many buildings, including apartment houses for about 5,000 people. It was located near the southern end of Sverdlovsk, a city of approximately 1.2 million at that time.
The military compound contained high-security facilities, including a factory that some people actually had thought was producing biological weapons. However, local and federal Russian authorities investigated and concluded that the epidemic was caused by the consumption of anthrax-contaminated meat. (Ingesting anthrax causes a rare form of the disease, called gastrointestinal anthrax.) This was the conclusion that was reported to the Russian people and the outside world at that time.
Articles in Soviet scientific journals then reported an outbreak of anthrax among livestock south of the city. The articles said that the citizens of Sverdlovsk ate anthrax-contaminated meat from these animals. The fact that the victims had chest findings characteristic of inhalation anthrax was not revealed. Additionally, the cover-up included confiscation by the KGB of the hospital and public health records of the epidemic. What's more, Dr. Abramova and her colleagues were asked to turn over all of their personal notes, official records, and specimens they collected from the autopsies they performed.
From the onset, foreign governments and scientists were suspicious about the official explanation for the fatal anthrax epidemic. There were numerous requests to allow independent scientists to investigate, but no one was allowed to go to Sverdlovsk. In this regard, it is important to know that the Russians had signed a treaty at the 1972 Biologic Weapons Convention banning biologic weapons research. The idea that the Russians had violated this treaty by producing anthrax fueled intense interest in the nature of the epidemic. Was the epidemic natural (for example, from contaminated meat), or did it result from an accident in a facility that was producing anthrax?
The Anthrax Outbreak Investigation
Finally, in 1992, after collapse of the Soviet Union, a group of scientists, including pathologists and epidemiologists, were allowed to visit Sverdlovsk to perform an on-site investigation. (Epidemiologists study the population and geographic characteristics of diseases.) The investigation was hampered, however, because, as mentioned above, the KGB had confiscated the hospital and public health records of the epidemic. The epidemiological studies, therefore, had to rely on administrative death records, visits to cemeteries, and interviews with family and friends of those who died.
Dr. David Walker, Chief of Pathology at the University of Texas in Galveston and a member of the visiting team, interviewed Dr. Abramova regarding her autopsy findings. Remarkably, Dr. Abramova and a few of her colleagues had hidden some of their personal notes, records from the autopsies they performed, microscopic slides from organs they examined, and even tissue samples preserved in formaldehyde. When Dr. Walker and others examined all of this material, it became clear that the epidemic was due to inhalation anthrax, not from eating contaminated meat. Thus, in 1992, for the first time, the outside world had proof that the epidemic was due to inhalation anthrax. The significance of this fact is that an epidemic of inhalation anthrax can only occur by inhalation of anthrax spores that were produced in an aerosol form.
Equally remarkable was the detective work done by the members of the team who were trying to identify the source of the inhalation anthrax epidemic. They used a variety of resources:
- Old street maps (the name of the city of Sverdlovsk has been changed to Ekaterinburg)
- Satellite photos of Sverdlovsk
- Weather reports
- Information on the whereabouts of all the victims
From all of this, the investigators pieced together a convincing and chilling reconstruction of what actually happened in Sverdlovsk early in April of 1979.
Here's what they learned. All of the deaths occurred in individuals who lived or worked in a narrow corridor south of military compound #19. From interviews, it was determined that the earliest exposure to the anthrax was on Apr. 2, 1979. Weather reports indicated that on Apr. 2 the wind was blowing from north to south, almost all of the day. Records of livestock deaths around Sverdlovsk showed that six towns reported livestock deaths due to anthrax after Apr. 2, 1979. All six towns were in a narrow corridor south of the city.
The scientific evidence was overwhelming! The outbreak of anthrax in the citizens of Sverdlovsk and the livestock south of the city was due to the wind-borne spread of an aerosol of anthrax spores. The source of the spores was military compound #19 and the escape of spores occurred on Apr. 2, 1979.
The Anthrax Outbreak Aftermath
In 1992, Russian president Boris Yeltsin was quoted as saying that the cause of the anthrax accident was "military developments" at compound #19. Thus, although he admitted that the anthrax came from an accident on the military compound, the Russian government released no other information. Theories on the nature of the accident include an explosion in a biological weapons factory on the military compound or workers at the factory forgetting to replace an exhaust system filter. To date, the exact nature of the accident and all of its ramifications, including the total number of victims, have not been disclosed.
However, we have still learned a number of important facts about anthrax as a result of this tragedy. For example, the incubation period (the time from exposure of people to the spores to the development of symptoms) ranged from one day to six weeks. The Sverdlovsk outbreak has also demonstrated some of the strengths and weaknesses of aerosolized anthrax as a biological weapon.
Strengths as a biological weapon include:
- A small amount of anthrax can kill many individuals.
- The spores can travel a significant distance. In Russia, they killed animals more than 30 miles away.
Weaknesses as a biological weapon include:
- The effectiveness of aerosolized anthrax will depend on such atmospheric conditions as wind speed and direction. For example, if the wind had been blowing north, toward the center of the city, many more individuals would have been infected.
- While 5,000 people who lived on the compound and 70,000 who lived south of the compound could have been infected, only about 100 died of the infection, even with this presumably weapons-grade anthrax.
- Since the deaths occurred over weeks, once anthrax is detected, there probably will be time to treat the majority of people exposed. A number of antibiotics are available that can be used to prevent the disease after exposure, or to treat the disease if infection occurs. There is a vaccine available to prevent anthrax, but it is not available to the general public yet.
Another significant consequence of the Sverdlovsk accident is that it led the U.S. Department of Defense to initiate intense research on the use of anthrax as a biological weapon. In addition, the U.S. Centers for Disease Control and Prevention (CDC) have been working with state and local health authorities to prepare for a bioterrorist attack using Anthrax (see CDC Emergency Preparedness and Response website for details). Nevertheless, most of the knowledge we have about anthrax as a biological weapon was generated as a result of the outbreak that began in Sverdlovsk, Russia, on Apr. 2, 1979. We could have learned more, however, if the Russians had been candid about the accident from the beginning. In the words of the investigators and the heroic Russian pathologists: "The tragedy of these deaths is compounded by the conditions of secrecy that have impeded elucidation of many facts that potentially would be useful in the future diagnosis and treatment of inhalation anthrax."
Anthrax is listed by the CDC as a Tier 1 biological agent. Tier 1 agents present the greatest risk to the public when deliberately misused (as a weapon) with a significant potential to disrupt the economy, the national infrastructure, public confidence or public health and safety. It was used in 2001 as a terrorist tool against US citizens. Powdered spores were placed in envelopes and sent through the US mail to people. Twenty-two people were infected (including untargeted mail handlers) and five people died from inhalation anthrax. This incident also closed down mail delivery hubs and office buildings thus disrupting normal activities until the areas were freed of anthrax spores. Although there is a vaccine for anthrax, because the disease is so rare in most countries, it is not routinely available to the public. Currently, antibiotics given early in the disease and to those likely exposed to the disease are the main measures used to halt or prevent anthrax in humans.
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The information in this article comes from a lecture by Dr. David H. Walker at a specialty conference on infectious disease pathology presented at the United States and Canadian Academy of Pathology meeting held on Mar. 16, 1994, and from two publications in scientific journals:
Abramova FA et al. Pathology of inhalational anthrax in 42 cases from the Sverdlovsk outbreak of 1979. Proceedings of the National Academy of Science, Volume 90, pages 2291-2294, March, 1993.
Meselson M et al. The Sverdlovsk anthrax outbreak of 1979. Science, Volume 266, pages 1202-1208, Nov. 18, 1994.
Addendum reference: CDC.gov. Anthrax.
Previous medical editor: Leslie J. Schoenfield, MD, PhD.