When Science Goes Wrong: Twelve Tales From the Dark Side of Discovery - Simon LeVay (2008)

MICROBIOLOGY: Gone With The Wind

ON APRIL 4, 1979, Anna Komina began to feel unwell. Her symptoms were not very specific: a feeling of faintness and dizziness, combined with a shortness of breath. After a day or so, she felt better, but on April 8 she collapsed. A doctor was called. He found that her blood pressure was dangerously low, and he summoned an ambulance. The emergency medical technicians struggled for several hours to raise her blood pressure to the point that she could be safely transported to the hospital. Two days later, she died.

Komina, who was 54 years old at the time of her death, was a resident of the city of Sverdlovsk, 850 miles east of Moscow, on the far side of the Ural Mountains. (The city is now known by its pre-revolutionary name of Ekaterinburg.) She lived in a modest cottage in an industrial southern district of the city known as Chkalovskiy, along with her husband, son, daughter-in-law, grandson and two pigs. She worked at a nearby ceramics factory, where her job was to check the temperature and pH of the water supply.

After Komina died, her body was autopsied. Her death was officially attributed to bacterial pneumonia. Then the body was doused in chlorinated lime, placed in a steel coffin, loaded onto a truck, taken to a special section of a local cemetery and buried - all at state expense. Komina’s husband was not invited, or even informed of the burial. He found out anyway and went to the cemetery, but the police would not let him in. Not long afterward, he died of grief.

Komina was not the only citizen of Sverdlovsk to die unexpectedly during the spring of 1979. During the six-week period starting on April 6, at least 76 other women and men came down with symptoms similar to hers. Massive doses of antibiotics and other medicines saved 11 of them, but at least 66 six persons died - some so quickly that they did not make it to the hospital alive. What killed them was anthrax.

The first that anyone in the West heard about the Sverdlovsk anthrax outbreak was in October of 1979, when a Russian-language newspaper catering to the émigré community in Germany ran a brief story alleging that thousands of Russians had died of the disease. In the same month, the US Central Intelligence Agency received descriptions of the outbreak from recent Russian émigrés. The mention of Sverdlovsk as the site of the outbreak raised a red flag, because the CIA suspected that a Soviet bacteriological institute in that city was engaged in germ-warfare research. The institute was housed in a high security area known as Compound 19 in the northern part of Chkalovskiy district. Nevertheless, the CIA analysts initially discounted the idea that the release of a disease agent from that facility might have caused the outbreak. ‘The probability is low that the Soviets were working with a quantity of highly lethal pathogens sufficient to cause 40 or more deaths without possessing either an effective vaccine or antidote,’ the analysts wrote in a top secret report.

The Sverdlovsk outbreak gained much wider publicity early the following year, when Germany’s mass-market tabloid, the Bild Zeitung, ran two reports about it. Bild never missed an opportunity to attack the Soviets, and it milked this story for all it was worth. The outbreak was caused by the explosion of anthrax-containing munitions at a germ-warfare institute, the newspaper announced, with subsequent release of the deadly bacterium into the atmosphere. Hundreds of people were affected: within seconds of inhaling the organisms they developed breathing difficulties, and death followed in a few hours. The CIA, Bild reported, had confirmed that a germ warfare institute was the source of the anthrax release.

Bild is not known for scrupulous fact-checking, and many details of its account were clearly wrong. Nevertheless, it was true that, by early 1980, the CIA had become more suspicious that the anthrax outbreak originated in Compound 19. For one thing, the agency learned that Soviet Defence Minister Dmitri Ustinov had made a visit to Sverdlovsk at the time of the outbreak, suggesting some involvement of the military. Also, when CIA analysts went back and scrutinised photographs of Sverdlovsk taken by spy satellites at the time of the outbreak, they noticed some odd things, such as roadblocks and what looked like decontamination trucks. Further, roads that had previously been dirt had suddenly acquired freshly tarred surfaces. These might all be signs of an organised response to an epidemic caused by airborne pathogens.

In March of 1980, the US State Department made their suspicions public in a statement which, though couched in terms of ‘indications’ rather than factual allegations, amounted to a serious indictment of the Soviet Union, because that nation, along with the United States and most other countries, had signed a Biological and Toxin Weapons Convention. This convention, which had gone into force in 1975, banned the development and production of bacteriological weapons. The treaty didn’t prohibit the Russians from doing research into defences against biological agents, such as vaccines, but the airborne release of enough anthrax to kill people over a wide area suggested that the bacteria were being produced in quantities far beyond what was necessary for vaccine development.

As might be expected, the Soviet response was one of indignation and injured innocence. Yes, there was an outbreak of anthrax, they said, but it was an entirely natural one. It had started among farm animals, and had spread to humans when meat from the slaughtered animals had been sold on the black market and eaten.

The anthrax organism, Bacillus anthracis, is present in many soils in the form of inert spores. It’s not unusual for grazing animals to become infected by ingestion of these spores - outbreaks or sporadic cases of gastrointestinal anthrax occur among farm animals in Russia from time to time. And humans can indeed develop gastrointestinal anthrax from eating infected meat. They can also develop skin lesions (cutaneous anthrax) from handling infected animal products such as hides.

Still, a couple of facts made the Soviet explanation a bit difficult to accept. For one thing, farm animals would not yet have been put out to pasture at the beginning of April - Sverdlovsk is in Siberia, after all - so their opportunities to acquire an infection were limited. Also, some of the symptoms reported among the human victims, such as shortness of breath, were more suggestive of inhalation anthrax - a rarer and more dangerous form of the disease in which the anthrax organisms enter the body through the thousands of tiny air sacs in the lungs.

Eventually, the CIA analysts settled on a kind of compromise hypothesis. The large cluster of human cases in early April must indeed have been caused by an airborne release of anthrax spores, they concluded, but the ‘tail’ of cases that occurred over the following six weeks probably had some other explanation. That was because, according to most medical authorities, the incubation period for anthrax is very short, so if a person doesn’t fall ill within two or three days of exposure, he or she will never do so. Perhaps these late cases were indeed gastrointestinal anthrax, caused by consumption of meat from animals that had themselves inhaled anthrax during the initial exposure event.

Lacking sufficient expertise in the field, the CIA consulted with a number of American scientists about the Sverdlovsk episode, including the Harvard molecular biologist Matthew Meselson. Meselson was one of the scientists who made notable contributions during the golden age of molecular biology in the 1950s and 1960s. He is most famous for a set of experiments, conducted with Frank Stahl, which proved that the double helix of DNA copied itself in the fashion predicted by Francis Crick and Jim Watson - by separating its two strands, each of which then provided the template for a new partner. He is the kind of scientist whom everyone assumes has won a Nobel Prize, but actually he hasn’t - not yet, at least. Now in his late 70s, he still runs an active research programme which is now focused on understanding why evolution favours sexual over non-sexual reproduction.

Since the 1960s, Meselson had been a strong proponent of restrictions on chemical and biological weapons, and he had worked from time to time as a consultant to the US government on the issue. He considered the international convention banning bioweapons manufacture to be an important milestone, and perhaps for that reason he was not particularly inclined to believe that the Soviets were violating their treaty obligations. Whatever his motivation, he expressed some scepticism about the CIA’s allegations.

Another series of events during the 1980s may have served to further undermine the CIA’s credibility in Meselson’s mind. This was the famous ‘yellow rain’ controversy. In 1981, US Secretary of State Alexander Haig publicly accused the Soviet Union of providing highly poisonous chemicals derived from fungi (mycotoxins) to its Communist allies in Vietnam and Laos, who had then used them in attacks against rebellious Hmong tribespeople. The Hmong had described the toxins as falling out of the sky in the form of a yellow rain, and said that persons touched by it quickly fell ill or died. The Hmong provided the CIA with samples of foliage covered by spots of ‘yellow rain’, and analysis of these spots supposedly revealed that they contained mycotoxins. These findings were the basis of Haig’s allegations.

Very soon thereafter, British scientists discovered that the spots contained partially digested pollen. This led Matt Meselson to hypothesise that the yellow spots were nothing more than bee faeces. With other scientists; Meselson went to Thailand and actually observed a shower of ‘yellow rain’ as a swarm of Asian bees engaged in a mass cleansing flight. He even found ‘yellow rain’ on the windshields of cars in Harvard University’s parking lots. Further analysis of both the original samples and newly obtained ones failed to confirm the presence of mycotoxins. While it is still a possibility that chemical agents were used against the Hmong, the yellow rain itself seems to have been an entirely natural and harmless phenomenon.

The yellow rain experience may have helped influence Meselson’s attitude about the Sverdlovsk allegations. Indeed, some recent accounts portray Meselson as becoming a flat-out nonbeliever in the CIA’s germ-warfare theory during the course of the 1980s. Judith Miller, Stephen Engelberg and William Broad - all writers for the New York Times - cited several statements by Meselson in their 2001 book, Germs, that seemed to indicate his acceptance of the Soviet explanation. In 1989, for example, they quote Meselson as testifying as follows before a Senate committee hearing: ‘The burden of the evidence available is that the anthrax outbreak was the result of a failure to keep anthrax-infected animals off the civilian meat market, as the Soviets had maintained, and not the result of an explosion at a biological weapons factory as previously asserted by the United States.’ And he added a general endorsement of the success of the Biological Weapons Convention. ‘Today, to the best of my knowledge, no nation possesses a stockpile of biological or toxin weapons.’

When I interviewed Meselson in 2006, he expressed some irritation with this portrayal. ‘I didn’t say that [the Soviet explanation of the Sverdlovsk episode] was necessarily correct,’ he told me. ‘They should have quoted what was on either side of that, which was that we really didn’t know, and the only way to find out would be to go there and [carry out] an independent investigation.’ As Meselson paints it, his attitude at the time was one of healthy scientific scepticism toward either side’s account. ‘There are a number of reasons why you might repave a road. There might be many reasons why a minister of defence would go to a certain city - he might have a girlfriend there, even. For me, coming from peer-reviewed science, we have to look more carefully: let’s create some hypotheses and see if we can disprove them.’

During the 1980s, Meselson did in fact make several attempts to organise a fact-finding trip to Sverdlovsk, but he was repeatedly stymied by a lack of cooperation on the part of Soviet authorities. This was probably due in part to their reluctance to allow anyone to investigate the anthrax outbreak, but in addition Sverdlovsk was generally off-limits to foreigners because it was a key node in the Soviet military-industrial complex.

Meselson did go to Moscow in 1986, however, where a high-level Health Ministry official by the name of Pyotr Burgasov told him that the anthrax outbreak had been caused by contaminated cattle feed - a story which explained how an animal outbreak could have occurred before animals were put out to pasture.

Two years later, Meselson brought Burgasov and two other officials to the United States where, in a series of lectures, they enlarged on this story. Most of the victims, they said, died of intestinal anthrax - and some of cutaneous anthrax that developed into a systemic infection - but none had inhalation anthrax, the form of the disease that would most likely have resulted from the release of anthrax spores into the atmosphere. Meselson seemed to accept this account, because he made public statements supporting its plausibility and once again criticised the official CIA viewpoint.

With the new policy of openness promulgated by Mikhail Gorbachev in 1990, stories began appearing in the Soviet press that linked the Sverdlovsk outbreak not to tainted meat but to activities at the military microbiological institute. Later that year, the Wall Street Journal published a series of three articles on the outbreak by Peter Gumbel, then its Moscow bureau chief. Gumbel had travelled to Sverdlovsk and interviewed some of the relatives of the victims. Tamara Markova, for example, recounted how her husband Mikhail, then 46, had come down with a cough during the first week of April 1979, and had died shortly afterward. ‘The doctor said his lungs looked like jellied meat,’ Tamara told Gumbel. This and other accounts, as well as interviews with persons who were familiar with the autopsies that had been performed on the victims, persuaded Gumbel that the anthrax infections had been acquired by inhalation, not by consumption of tainted meat.

Meanwhile, inside information about the alleged Soviet germ warfare programme became available. In late 1989, Vladimir Pasechnik, the director of the Institute of Ultrapure Biological Preparations in Leningrad, defected to Britain. There, he recounted to intelligence agents how his institute had been working on methods of delivering bacteriological agents. His own institute, Pasechnik said, was just one element of a massive network of germ warfare facilities known as Biopreparat, which employed 30,000 workers across the Soviet Union. Lethal bacteria such as plague and anthrax were manufactured and stored at these facilities, ready to be loaded into munitions and delivered by specially-adapted planes, cruise missiles and even intercontinental ballistic missiles. The weapons had been successfully tested on tethered monkeys on an island in the Aral Sea.

The Soviet Union, if Pasechnik’s statements were to be believed, was violating the Biological Weapons Convention in the most flagrant way, though ironically Pasechnik said that he had never heard of the convention. His allegations did not become public knowledge until 1992, and he apparently did not provide specific information about the cause of the Sverdlovsk anthrax outbreak.

After the break-up of the Soviet Union in 1991, many embarrassing secrets of the Soviet era were exposed. In November 1991, a Russian general told the newspaper Izvestiya that the Sverdlovsk anthrax outbreak had originated at the bacteriological institute when workers had failed to activate safety filters, leading to a massive release of the bacterial spores into the atmosphere. In May of the following year, Russian President Boris Yeltsin (who had been the Communist Party boss in Sverdlovsk at the time of the anthrax outbreak) officially admitted that the outbreak had been caused by the Soviet military. He said that he gave orders for the bacteriological-warfare programme to be terminated.

‘In a sense you could say that he scooped us,’ Matt Meselson said of Yeltsin’s announcement. Scientists, like journalists, hate to be scooped: priority is everything. One way that scientists often deal with this problem is by minimising the significance of other people’s findings that anticipate their own. In this case, Meselson suggested to me that Yeltsin didn’t really have any solid reason to make the statement he did. ‘It was pretty slim evidence,’ he told me. It wasn’t based on an actual admission of guilt by the military, but on an unverified statement from one of Yeltsin’s advisors - a biologist named Alexey Yablokov - to the effect that ‘someone had found anthrax spores on a wall hanging of some kind’.

Peter Gumbel, the Wall Street Journal reporter, received the same treatment. Gumbel’s account was so full of errors as to suggest that he never visited the area affected by the outbreak, according to a 2002 article by Boston College sociologist Jeanne Guillemin, who is Meselson’s wife and one of his collaborators in the Sverdlovsk study.

In a recent email to me, Gumbel fired back. ‘I had just driven a 10-ton truck through [Meselson’s] credibility,’ he wrote. ‘He had staked his academic reputation on some Cold War lies. At best, he had been duped by some fairly crude propaganda. At worst, he was a naive apologist for a nasty regime. I imagine his Harvard colleagues snickered behind his back… And then his wife comes back and tries to trash me in her official account. I was surprised by the pettiness. It would have been more professional to acknowledge the groundwork that I did… As far as I know, I didn’t get my facts wrong. Unlike certain others…’

In any event, the gradual flow of revelations made Meselson’s willingness to believe the Soviet denials less and less tenable, but they also gave him the opportunity he had long wished for - to visit Sverdlovsk and find out the truth for himself. In early 1992, with Yablokov’s help, Meselson obtained an invitation from Ural State University to come to Sverdlovsk to carry out an investigation.

In June of 1992, a team of five researchers went to Russia: Matt Meselson, Jeanne Guillemin, Alexis Shelokov, David Walker and Martin Hugh-Jones. Guillemin spoke some Russian, and her role would be to carry out and analyse interviews with families and survivors. Shelokov was a public health expert from the Salk Institute and a native Russian speaker. Walker, a pathologist from the University of Texas, would review any autopsy data they could find. Hugh-Jones, a veterinarian from Louisiana State University, would be in charge of investigating the anthrax outbreak as it affected animals. The team gave themselves two weeks to unravel a 13-year-old mystery.

In Moscow, the group met with Pyotr Burgasov, the Health Ministry official (now retired) who had presented the ‘tainted meat’ story to the world. He stuck by this story, even though it was by now widely discredited and he himself was being portrayed in the Russian media as an accomplice of the KGB. Then the group travelled on to Sverdlovsk.

Meselson and his colleagues wanted to find out who had contracted anthrax, where and when they had contracted it, what their symptoms were and what the autopsies revealed. Unfortunately, most of the relevant documents such as hospital case records were missing: they had been confiscated by the KGB soon after the 1979 outbreak. Meselson did know, however, that the anthrax victims were buried in a special section of a local cemetery. On Saturday June 6, the group went to the cemetery, where they indeed found a section containing 66 graves of men and women who had died in the six-week period beginning April 8, 1979. These included the graves of Anna Komina, whose death was recounted at the beginning of this chapter, and Mikhail Markov, the man whose widow was interviewed by Peter Gumbel. Interestingly, there were no children among the victims. In fact, there were no family groupings: the victims were unrelated to one another. This was somewhat inconsistent with the ‘tainted meat’ story, because one might expect several family members to be struck down if tainted meat was served.

The researchers now had a list of the victims’ names, ages, and dates of death, but not yet their places of residence or work, nor any means to contact their relatives. But more information, including some of the victims’ home addresses, was provided by Margarita Ilyenko, a physician who was the director of one of the hospitals that received the anthrax victims. Ilyenko had not only treated the victims and saved some of their lives; she had also helped organise the community response, recruiting volunteers to survey the affected households, carry out disinfections and the like. She described how the bodies of the victims had overflowed the hospital’s morgue and piled up outside, while no one dared go near them for fear of catching whatever had caused their death.

Later, toward the end of the team’s visit to Sverdlovsk, a Supreme Soviet deputy by the name of Larissa Mishustina handed the team an official list of 64 victims, with their addresses. The KGB had prepared the list after Boris Yeltsin ordered the victims’ families to be compensated - something that was never actually done.

With this information, Jeanne Guillemin began touring the streets of the Chkalovskiy district where many of the victims had lived. As an interpreter she had Olga Yampolskaya, a Moscow physician who had joined their team. During the anthrax outbreak, Yampolskaya had been an assistant to the head clinician dealing with the outbreak, and she had herself treated some of the victims. Guillemin’s and Yampolskaya’s task was to knock at the addresses on her list and ask if the current resident was a relative of the deceased. In the Soviet era, people rarely moved and, although 13 years had passed, a surprisingly large number of the homes she visited were still occupied by the victims’ spouses or children.

When they knocked at the address given for Fagim Dayanov on Escadronaya Street, for example, they found his widow, Rema. She told them that Fagim, like several other victims, had been employed at the ceramics factory, which was situated three kilometres from Compound 19 in a south-easterly direction. Fagim had remained healthy during the first few weeks of the outbreak. When the cause was identified as anthrax, vaccinations were made available; Rema agreed to be vaccinated but Fagim refused. On May 3, probably as part of the disinfection campaign, Fagim was told to clean the roof of the factory. He became ill on May 4 and was taken to the hospital on May 6. Rema and their son were not allowed to visit him until three days later, by which time he was desperately ill. The couple was kept separate by a glass partition and had to communicate by exchanging notes. On the evening of May 10 Fagim wrote: Rema - don’t go home. We may never look into each other’s eyes again. Rema eventually did go home, and Fagim died that night. When Rema returned to the hospital, not knowing that her husband was dead, she was directed to the morgue, where her husband’s body lay on a gurney, naked, with his chest, abdomen, and braincase sliced open. The autopsy had already been completed.

Besides these often-painful interviews with the victims’ relatives, Meselson’s team had extensive discussions with the two pathologists, Faina Abramova and Lev Grinberg, who had conducted most of the autopsies. It was Abramova who made the initial diagnosis of anthrax, based on the observation of the anthrax bacillus in tissue samples. She related how the KGB had come to her hospital to confiscate all the medical and autopsy records and tissue samples, but she successfully hid much of the material: she placed jars containing tissue samples among other items in her pathology museum, and she concealed paperwork in filing cabinets devoted to other matters. Thus, Abramova and Grinberg were able to give Meselson’s team a comprehensive description of 42 cases. All of them had shown signs of infection in the thoracic cavity, with bleeding from thoracic lymph nodes and from the mediastinum (the area between the left and right lungs). Some victims also had involvement of the gut, but this involvement was probably secondary to a systemic infection, because the mesenteric lymph nodes (the nodes that receive lymph from the intestines) were affected in only a few cases. In short, the pathological findings were consistent with inhalation anthrax in most or all cases, just as Peter Gumbel had concluded in his Wall Street Journalarticles the previous year.

The two weeks that Meselson’s team had allotted themselves for the trip to Russia came to an end before they were able to carry out most of their interviews with the victims’ relatives, and they resolved to make a return trip the following year. Nevertheless, even with the results that they obtained on the 1992 visit, two things were clear: the outbreak was caused by the airborne release of anthrax spores and, second, most of the victims either lived or worked in the Chkalovskiy district of Sverdlovsk at the time they became ill. The researchers’ findings were thus pointing strongly toward the conclusion that Meselson had long resisted, namely that the outbreak was caused by an accident at Compound 19, the suspected germ-warfare institute.

In the autumn of 1992, an event occurred that to some degree made Meselson’s investigations irrelevant. The second-in-command at Biopreparat, the network of Soviet facilities that Vladimir Pasechnik had fingered as a germ warfare agency, defected to the United States. His name was Kanatjan Alibekov, but he later anglicised it to Ken Alibek. When interviewed by the CIA, Alibek poured out a truly horrifying account of the Soviet germ warfare programme, a description that went far beyond what Pasechnik had revealed. Among other things, he said that the Soviets had produced hundreds of tons of anthrax. The lethal dose of anthrax when inhaled is about 10,000 spores, or ten billionths of a gram, so the Soviets had manufactured enough of the spores - in theory - to kill the entire population of the planet millions of times over. Alibek identified Compound 19 as being heavily involved in research, production and weaponisation, and he said that he himself had developed a strain of anthrax that was far more lethal than those that occurred in nature.

Meselson was still determined to complete his own study, and in August of 1993 he and Guillemin returned to Sverdlovsk. They interviewed more relatives of the deceased victims, as well as some of the few victims who had recovered, and they obtained detailed information about the victims’ whereabouts during the outbreak. In addition, they visited several villages outside Sverdlovsk where farm animals had come down with anthrax during the same period. One place they were not allowed to visit was Compound 19, the suspected site of anthrax release; although anthrax production had probably long ceased it was still a military facility, and Meselson could not obtain the required authorisation to enter.

Back in the United States, Meselson and Guillemin put all the information together in an attempt to pin down the time and place of the anthrax release. The first person to fall ill, a 48-year-old ceramics factory employee named Vera Kozlova, did so on Wednesday April 4, so there must have been some release of anthrax before then - probably a day or two before, given what was known about the minimum incubation period for inhalation anthrax. So many victims fell ill in the few days after Kozlova was struck down that it seemed likely that a single release event very early in that week had caused most of the infections.

Looking at their records, Meselson and Guillemin saw that nearly all the victims either lived in the Chkalovskiy district to the southeast of Compound 19, or had worked in or visited that district in the relevant time span. Six victims lived or worked in Compound 19 itself. As already mentioned, several of the victims worked at the ceramics factory southeast of Compound 19. Another group of victims were five military reservists; these men all lived and worked outside of Chkalovskiy, but during the week starting Monday April 2, all five took a course at Compound 32, a military facility immediately to the south of Compound 19. The reservists came in each morning and left the district in the late afternoon. This strongly suggested that the anthrax release occurred during daytime hours on one of the weekdays from April 2 to April 6, most likely on April 2 or April 3, given that the earliest disease onset was on April 4.

When the researchers took a map of Sverdlovsk and plotted the daytime locations of all the victims during this time span, a striking pattern emerged. Nearly all the victims were located in an extremely narrow, cigar-shaped zone that began in Compound 19 and extended in a south-easterly direction. The closest victims - six of them - had been within Compound 19 itself. The most distant had been four kilometres away on the south-eastern outskirts of the city. Although no humans were affected beyond that distance, animals were: the veterinary cases occurred in six villages that lay precisely along a continuation of that south-easterly line. The most distant of these villages lay more than 50 kilometres from Compound 19.

Five victims were ‘outliers’ - they neither lived nor worked in the high-risk zone. Three of them had occupations, such as truck driver, that might have taken them into the zone. Information about the other cases was lacking.

Thus it was clear to the researchers that the anthrax cloud had originated at Compound 19 and the wind had blown it toward the southeast. This was the final clue that allowed Meselson to pin down the date of the accident. Sverdlovsk airport, like all major airports around the world, reports weather conditions every three hours to a United Nations agency, and this information is archived by the US National Center for Atmospheric Research in Boulder, Colorado. When he obtained the records for the week in question, Meselson found that the wind had blown steadily to the southeast or south-southeast throughout the daylight hours on Monday, but never blew in that direction during the following two days. The wind did blow to the southeast for part of the day on Sunday April 1, but this day was ruled out because the military reservists were not in the area until Monday. Thus Monday, April 2, was pinned down with near certainty as the date of the incident. As icing on the analytical cake, it turned out that one of the reservists had attended classes at Compound 19 on only a single day - Monday.

Meselson now turned to another question: how much anthrax was released? To answer this, he had to make a lot of ‘guesstimates’ about factors such as the height of the release above ground, atmospheric conditions and the number of spores that would be required to cause a fatal infection. In the end, he concluded that the total release was quite small - less than a gram (four hundredths of an ounce), and perhaps as little as a few milligrams.

The researchers published their findings in two papers. A 1993 paper in the Proceedings of the National Academy of Sciences presented the evidence from the pathological investigations, which pointed to the conclusion that most of the anthrax infections were acquired by inhalation and not by food consumption. In the following year, Meselson’s group published a paper in Science in which they presented the findings of their epidemiological studies, including the time, place and estimated amount of anthrax release.

Together, the two studies presented far more detailed and convincing evidence that the anthrax outbreak originated in the biological warfare facility than had any previous investigation. No one reading the Science paper could fail to be impressed by how weeks of plodding epidemiological footwork had allowed the researchers to plot a cigar-shaped ‘arrow’ that pointed unmistakably and accusingly at Compound 19.

Still, the study did have its detractors. For one thing, there were some who felt the whole topic was moot, given that the Russians had already admitted that their germ warfare institute caused the outbreak. Also, Meselson had not been able to answer the question that people were now asking, which was what exactly went wrong in Compound 19 that led to the anthrax release. Finally, there were some critics, such as germ-dispersal expert Bill Patrick, of Fort Detrick (home to the US Army Medical Research and Materiel Command), who felt that Meselson’s estimate of the amount of anthrax released was far too low. ‘We hooted [when we heard his numbers],’ is what Patrick told the authors of Germs.

The significance of the dispute over the amount of anthrax released is this: if the amount was very small, it was conceivable that it happened not as a result of weapons production but in the course of legitimate research or vaccine development - activities that were permitted under the Biological and Toxin Weapons Convention. Tom Mangold and Jeff Goldberg, in their 1999 book Plague Wars, suggested that Meselson gravitated to a low estimate because he was clinging to his long-held hope or belief that the Soviets were abiding by the convention. They dug up some statements made by Meselson in the mid-90s that were consistent with this interpretation. Still, Meselson sticks by his estimate, and it has recently been confirmed in a re-analysis by physicist Dean Wilkening of Stanford University.

One still-unresolved mystery has to do with the ‘tail’ of anthrax cases which extended for six weeks beyond the initial outbreak. Most of these victims clearly had inhalation anthrax, not the gastrointestinal form, so it doesn’t seem likely that they got sick from eating tainted meat, as the CIA analysts had originally proposed. How then had they acquired their infections?

One theoretical possibility is that the anthrax release was not a single event but continued for several weeks, albeit at a lower rate. If this were the explanation, however, one would expect the later victims to be located in other places than in the cigar-shaped zone where the early victims lived or worked, because the wind blew in other directions on later days. In reality, they were located in exactly the same high-risk zone as the early victims.

A second possibility would be that the later victims acquired their infections from anthrax that had been deposited on surfaces during the initial release and then re-entered the atmosphere at some later time. Such an explanation seems particularly appropriate for victims like Fagim Dayanov who, as described earlier, fell ill in early May, a day after he was sent to clean the roof of the ceramics factory. Did he stir up a secondary aerosol of anthrax during that cleaning operation and thus breathe in enough spores to develop an infection?

When I asked Matt Meselson about this, he acknowledged that secondary infections were a possibility, but he considered this explanation unlikely. Anthrax spores are so tiny, he told me, that once they bind to surfaces they are held there by surprisingly strong electrostatic forces and are very difficult to pull back into the atmosphere. Larger clumps of spores can be re-aerosolised, but such clumps are not effective infectious agents because they do not penetrate deep into the air sacs of the lungs, which they need to reach order to trigger an infection.

Meselson favours a third explanation for the late cases, which is that those victims inhaled the anthrax spores on Monday April 2, just like the early victims, but simply took longer to fall ill - up to six weeks in some cases. This contradicts conventional medical wisdom, which says that the incubation period for inhalation anthrax is just a very few days - just one day in some cases. Meselson dug up some old studies, however, in which monkeys were exposed to anthrax by inhalation. Some of these monkeys took weeks to fall ill. Such long incubation periods were not observed in more recent studies, but according to Meselson that was because researchers simply didn’t wait that long - the animals were sacrificed after a few days whether they were sick or well.

In theory, analysis of the late victims’ locations during the outbreak could resolve this issue: if victims such as Dayanov had been away from Chkalovskiy during the first week of April and then returned to the high-risk zone before becoming ill, that would suggest that they acquired their infection from secondary aerosols. Such cases were not found, but the numbers are too small to make a definitive judgment on this basis. Thus, the question of how the victims in the tail of the outbreak acquired their infection remains unresolved.

How exactly did the anthrax release come about? In 1999, Ken Alibek, the defector who ran the Soviet germ-warfare programme, came out with his own book (written with Stephen Handelman), titled Biohazard. In it, Alibek presented a detailed account of what he was told happened:

On the last Friday of March 1979, a technician in the anthrax drying plant at Compound 19, the biological arms production facility in Sverdlovsk, scribbled a quick note for his supervisor before going home. ‘Filter clogged so I’ve removed it. Replacement necessary,’ the note said.

Compound 19 was the Fifteenth Directorate’s busiest production plant. Three shifts operated around the clock, manufacturing a dry anthrax weapon for the Soviet arsenal. It was stressful and dangerous work. The fermented anthrax cultures had to be separated from their liquid base and dried before they could be ground up into a fine powder for use in aerosol form, and there were always spores floating in the air. Workers were given regular vaccinations, but the large filters clamped over the exhaust pipes were all that stood between the anthrax dust and the outside world.

After each shift, the big drying machines were shut down briefly for maintenance checks. A clogged air filter was not an unusual occurrence, but it had to be replaced immediately.

Lieutenant-Colonel Nikolai Chernyshov, supervisor of the afternoon shift that day, was in as much of a hurry to get home as his workers. Under the army’s rules, he should have recorded the information about the defective filter in the logbook for the next shift, but perhaps the importance of the technician’s note didn’t register in his mind, or perhaps he was simply overtired.

When the night shift manager came on duty, he scanned the logbook. Finding nothing unusual, he gave the command to start the machines up again. A fine dust containing anthrax spores and chemical additives swept through the exhaust pipes into the night air.

In attributing the accident to a failure to replace a filter, Alibek’s account meshed well with the statement made by a Russian general to Izvestiya in 1991, as described earlier. On the other hand, there are details that are inconsistent with the findings of the Meselson group, most notably the date and time of the anthrax release. If the Meselson group is right, Friday March 30 is definitively ruled out, because the wind was blowing in the exact opposite direction - toward the northwest - on that day, which would have carried the lethal plume toward downtown Sverdlovsk and away from the Chkalovskiy district. Also, the military reservists were not in the area at any time on that day.

In a 2006 interview, I asked Alibek how he came by the information about the accident that he presented in his book. He said that it was told to him by a senior scientist by the name of Mikhail Kuzmitsch during a two-hour train ride in 1983. Kuzmitsch was working in the anthrax plant at the time of the accident. When I pressed him about the inconsistencies with Meselson’s account, he replied with the kind of non-answer that surely reflected decades of training in the Soviet bureaucracy. ‘I respect his work,’ he said, ‘and he respects mine.’

I suggested a possible resolution, which was that the removal of the filter did happen at the end of the day shift on Friday as Kuzmitsch told him, but that the plant lay idle over the weekend and wasn’t started up until Monday, so that the release was delayed until that day. Alibek agreed that this was a possibility, and added that he wasn’t sure whether the plant would have been running through the weekend.

In her book, Jeanne Guillemin gave Alibek the same treatment she meted out to Peter Gumbel: she took him to task for the apparent errors in his account, and suggested that they threw his entire explanation for what had happened into doubt. Meselson took a mellower view of the matter. He reminded me that details such as dates can easily change as they are stored in memory or reported to others. ‘The fundamentals are correct,’ he said. ‘The only thing we disagree about is the day of the week - a pretty small detail.’

Given that the origin of the anthrax outbreak in the germ warfare institute has been admitted by the president of Russia, described in detail by the onetime boss of the Soviet germ warfare programme, and proven by Meselson’s research, one might think that there would be universal acceptance of this explanation. Jeanne Guillemin told me, however, that a book on infectious diseases distributed recently by the Russian Ministry of Health attributes the outbreak to - yes - tainted meat.

As far as is known, Russia and the United States (and the United Kingdom) now adhere to the Biological and Toxin Weapons Convention and no longer have any military stocks of anthrax or other pathogens. The country whose continued engagement in production of biological weapons has aroused the greatest concern is Iraq. Although Iraq signed the convention in 1972, Saddam Hussein instituted a biological weapons programme soon after he came to power in 1979; it included the manufacture of anthrax, plague, botulinum toxin and aflatoxin, albeit in nothing like the quantities reported for the Soviet Union. Saddam was apparently deterred from using these weapons during the 1991 Gulf War by the threat of overwhelming military reprisals on the part of the United States. In the diplomatic battles preceding the 2003 invasion of Iraq, his alleged possession of weapons of mass destruction, including bacterial weapons, was a central issue, but none were found either by UN inspectors before the invasion or by the US/British forces afterward. Apparently, Saddam had been telling the truth when he said that he had terminated those programmes and destroyed existing stocks of biological agents.

In the dark days after the terrorist attacks of September 11, 2001, the American people were put in a state of even greater alarm by a series of small-scale but deadly attacks involving anthrax. Several letters containing anthrax in powder form were mailed to national news organisations and politicians. The intended targets, who included NBC television news anchor Tom Brokaw, Senate Majority Leader Tom Daschle and Senator Patrick Leahy, escaped harm, but 22 other people contracted anthrax infections and five of them died. In August 2002, Attorney General John Ashcroft named Steven Hatfill, a former Army bioweapons researcher, as a ‘person of interest’ in the investigation of the attacks, but in March 2008 Hatfill was officially exonerated, and he received a multimillion-dollar settlement from the Justice Department. The FBI then focused on another suspect, Bruce Ivins, a senior biodefence researcher at Fort Detrick who had himself participated in the investigation of the anthrax attacks. Ivins committed suicide in July 2008. Shortly thereafter the Justice Department announced its conclusion that Ivins was the sole perpetrator of the anthrax mailings. Ivins had a history of mental instability, but the exact motivation for his actions remains a matter of speculation.

Another accident involving the airborne release of a virus from a laboratory occurred in England less than a year before the Sverdlovsk incident. The virus was smallpox, and the release was not from a military facility but from the laboratory of Henry Bedson, a smallpox researcher at the University of Birmingham.

Janet Parker, a 40-year-old medical photographer who worked on the floor above Bedson’s laboratory, apparently inhaled virus particles that had entered her workspace through the building’s ventilation system. Parker died - the last person on Earth to be killed by smallpox, which was eliminated in the wild in 1977. A few days after her diagnosis, but before she died, Henry Bedson walked down to the potting shed at the bottom of his garden and committed suicide by slashing his own throat.