Sydney: Conflicting information about the death of a laboratory worker at a Russian plague research institute has fuelled concerns about the possibility of pneumonic plague spreading. Nearly 200 people are in quarantine in Siberia after 28-year-old Darya Shipilova fell ill at work and died on October 2. The circumstances surrounding her death remain unclear. A senior Russian official wrote on social media last week that Shipilova “had died from the plague”, before editing the post to add “possibly”. Russia’s health watchdog has since said she died from “pneumonia of unknown etiology”. Local media reports have suggested she became infected following an accident at the Irkutsk Anti-Plague Research Institute of Siberia and the Far East, where she worked, but these reports have not been confirmed.
Plague is caused by the bacterium Yersinia pestis. The bacteria generally live in ground-dwelling rodents such as rats and prairie dogs, but can also infect humans. The same Y. pestis bacterium can cause three forms of plague.
Bubonic plague spreads from animals to humans through fleas and causes swelling, known as buboes, in the lymph nodes. Other symptoms include fever, headache, chills and weakness. Without antibiotics, bubonic plague can kill within a few days, with between 30 and 60 per cent of people who contract the disease dying.
Septicemic plague occurs when untreated bubonic plague spreads, although it can also develop directly when the disease enters the bloodstream. It causes bleeding into the organs and involves septicemia, a serious blood infection.
Pneumonic plague, the suspected but unconfirmed cause of Shipilova’s death in Siberia, can develop when bubonic plague spreads to the lungs. It can also spread directly from person to person through tiny respiratory droplets. Pneumonic plague is the rarest but most severe form, with a fatality rate of up to 100 per cent if left untreated. Alongside other symptoms, it causes severe pneumonia, an infection of the lungs caused by bacteria.
Bubonic plague was responsible for the deaths of tens of millions of people in the western Mediterranean between 541 and 750 CE during the Plague of Justinian and killed up to half of Europe’s population during the Black Death in the Middle Ages.
However, plague outbreaks have continued since medieval times. A third pandemic spanning the late 19th and early 20th centuries killed up to 12 million people.
Plague remains endemic to Central Asia, Africa, the Americas and Siberia, where the Russian lab worker died last week. This means the disease is present at a steady, consistent level in these regions.
Cases typically occur in rural and agricultural areas, making a potential laboratory leak in an urban area unusual.
Yes. A 10- to 14-day course of antibiotics, either oral or intravenous, can treat plague as long as the drugs are taken soon after infection.
However, several antibiotic-resistant strains have been detected in the wild since 1995.
In the 1980s, Soviet Union scientists also engineered resistant strains. This history forms the basis of hypothetical scenarios involving biological warfare.
There is no evidence that the strain alleged to have killed Shipilova could not be treated with antibiotics or that the laboratory is researching biological weapons.
There has been only one documented major outbreak of pneumonic plague, in China in the 1910s.
Little is still known about the Siberian case. At this stage, however, there is little evidence to suggest a risk of an epidemic, which is localised, or a pandemic involving multiple countries.
The World Health Organisation (WHO) said in a statement on Monday that it was aware of reports that a laboratory worker in Irkutsk had “died of severe pneumonia”, but said no cause of death had been officially confirmed.
The WHO statement also said: “Based on unofficial information available, the public health risk to the general population appears to be low. The risk assessment will be updated once more information is available.”
Assessing the risk will depend on access to transparent information about how Shipilova became ill and died.