DAVID HESLOP: In the spring of 1979, an unusual infectious disease outbreak suddenly occurred in the Soviet city of Sverdlovsk, an industrial city of 1.2 million people located 1,400 kilometres east of Moscow on the route to Siberia. Sverdlovsk was known for light industry, manufacturing, agriculture, and its ties to the military industrial complex. By Soviet standards, it was a modern and vibrant city with a hardworking, loyal, and industrious population that enjoyed many of the best services and facilities that the Soviet Union could provide. In early April, doctors at the general hospital suddenly began to receive unusually severe cases of sepsis. Over the following days, these cases became rapidly worse. And despite dramatic efforts to treat them, most died.
Some others presented to the clinicians with unusual skin lesions, crusted and black. Some were found to have unusual findings on medical investigations like chest X-ray. And other standard treatments and antibiotics seemed not to help. In around six weeks, 64 cases of this unusual infectious disease had died. And thousands have been affected in Sverdlovsk. An apparently anxious government stepped in to control information. And years later there was a gradual emergence of the true facts surrounding an event whose gravity and implications lay under layers of secrecy, suspicion, and doubt for decades. This was the Sverdlovsk anthrax outbreak of 1979. The first cases came into hospitals on the 4th of April presenting with cough, fever, chest pain, and shock.
A range of treatments were tried from high-dose antibiotics through to specialist supportive care without effect. Young, fit, and healthy workers were being struck down with this severe, primarily respiratory illness. The condition of the affected patients rapidly deteriorated, resulting in death around three to six days after initial presentation. Frontline clinicians, pathologists, and scientists were puzzled. And an urgent initial investigation was commenced. By the 10th of April, hospital authorities had identified the causative agent for the severe infections and deaths as Bacillus anthracis, otherwise known as anthrax. So let’s explore what anthrax is. Bacillus anthracis is a spore-forming bacteria that causes anthrax, a zoonotic disease primarily found in domesticated and wild animals, such as herbivores– goats, sheep, cattle, horses, and swine.
Humans have historically become infected through contact with infected animals or contaminated animal products, either handling the hides of contaminated animals or by ingesting meat derived from infected animals. Historically, the most common root of exposure is cutaneous, leading to cutaneous anthrax disease. In the 19th century, a previously unrecognised form of the disease, inhalational anthrax, was observed in occupations that handled anthrax-contaminated hides, such as wool sorting. When handling the contaminated hides, anthrax spores would become airborne and then be inhaled by the workers. Inhalational anthrax causes rapid onset and severe symptoms and signs in those infected. From the most frequent to the least common, they are fever and chills, shortness of breath, cough, chest pain, abdominal pain, headache, and vomiting.
This then, in most cases, leads to severe sepsis, shock, and then death. At times, death can occur so rapidly that a previously well-looking patient can collapse and die within hours. Gastrointestinal anthrax causes similarly rapid decline and death. It is thought that anthrax mortality can be as high as 100% once symptoms have commenced and approximately 50% even with the most advanced intensive care techniques. In contrast, cutaneous anthrax has a much lower mortality rate when compared to inhalational and gastrointestinal anthrax. The mortality rate of cutaneous anthrax is around 30% if untreated and less than 10% if treated with appropriate antibiotics. Once exposed, the incubation period is generally very short– two to six days.
And death generally occurs three to four days after symptoms commence. Once contracted, anthrax is not transmissible to other humans and not between animals. The combination of lack of transmissibility with ease of dispersal, low infectious dose, and lethality is the reason why anthrax is one of the most feared possible bioterrorism agents. So what was occurring here in Sverdlovsk? Was this a natural outbreak? Had there been a deliberate release of a bioterrorism agent, or had something else occurred? Authorities were quick to act once the causative agent was identified. Experts from key research institutes across the Soviet Union were enlisted to assist with the management of the outbreak.
The authorities release statements to the public that the cause of the outbreak was from the illegal sale of contaminated meat. A public health response was undertaken that included medical and sanitation teams visiting homes and taking focused histories and undertaking contract tracing, placing contacts of cases of anthrax on prophylactic antibiotics, taking meat and environmental samples from vendors and suppliers of meat in Sverdlovsk, disinfecting the homes of anthrax cases, washing down buildings, streets, and trees in affected areas, culling stray animals such as feral dogs, and communicating with the public through newspaper articles warning citizens not to eat uninspected meat or have contact with sick animals.
Additionally, a voluntary immunisation programme for individuals living in the southern area of Sverdlovsk was also initiated. And ultimately, 80% of the 59,000 eligible people in the area affected were vaccinated at least once. Despite the public messages, treating clinicians and scientific experts in Sverdlovsk had significant doubts about the origin of this outbreak. Key questions remain such as, if this was gastrointestinal anthrax, why was the predominant finding on autopsy severe pulmonary anthrax? Where was the evidence that supported gastrointestinal anthrax, such as a common source or pattern of exposure? Why was there such secrecy surrounding some of the clinical results from anthrax cases?