Mint Explainer: What do we know about Russia’s suspected plague outbreak?

A Siberian lab worker's death has triggered hundreds of quarantines and global monitoring, though Russian officials deny a pneumonic plague outbreak and WHO assesses the risk as low.

Hundreds of people in Siberia have been quarantined after a laboratory worker at a plague research institute died in undisclosed circumstances on Friday. A Russian news outlet reported the woman may have contracted pneumonic plague from a broken test tube, a narrative that Russian health authorities have denied.

As global health bodies and governments seek more information, Russia has said that the worker’s death does not risk an epidemic in Siberia. However, public health experts are vigilant, given the limited information available.

Mint explains the situation, how global authorities have responded, and whether there is cause for worry.

What happened in Russia?

Darya Shipilova, a 28-year-old laboratory worker at the Irkutsk Anti-Plague Research Institute of Siberia and the Far East, fell sick on 29 September and died, reportedly on 2 October. The institute studies plague and other dangerous infectious diseases. Russian authorities said she died from pneumonia of ‘unknown’ origin, meaning the precise illness has not been established.

Some Russian media outlets reported that she may have been exposed to pneumonic plague after accidentally breaking a test tube containing the bacteria. However, Russian authorities have denied such an accident occurred. Other unverified accounts linked her illness to recent travel, but there is no publicly available evidence for these claims.

Her death, however, prompted rapid precautionary measures, with authorities placing about 200 people who’d had contact with Shipilova under medical observation. However, Russia’s health watchdog said on Tuesday that nearly 5,000 laboratory tests had been carried out, no plague had been detected among her contacts, and about 90% of those initially quarantined had been released.

What is the plague?

Plague is an infectious disease caused by bacteria that naturally circulate among rodents and other small mammals and their fleas. Humans can become infected through flea bites, contact with infected animals or, in the case of pneumonic plague, through respiratory droplets from an infected person.

There are three principal forms of plague. Bubonic plague, the most common form, affects the lymphatic system and causes characteristic painful swellings called buboes. Septicemic plague occurs when the bacteria infect the bloodstream. Pneumonic plague affects the lungs and is the form that has raised concern in Russia.

Pneumonic plague is particularly serious because it can spread between people through droplets produced when an infected person coughs or sneezes. While the nature of the transmission may lead to comparisons with covid-19, plague transmission requires close and prolonged contact to a person who is already showing symptoms. Also, unlike viral respiratory infections, plague is a bacterial disease and can thus be treated with antibiotics.

How has the world responded?

Neighbouring countries Kazakhstan, Kyrgyzstan and Uzbekistan have stepped up precautionary measures at their borders to guard ​against the possible spread of infectious diseases.

Meanwhile, global health authorities are seeking more information on the case. WHO director-general Tedros Adhanom Ghebreyesus said the organization requested information from Russia on Saturday, after reports of the death emerged, saying the agency does not have a “full picture” of the situation yet. The European Centre for Disease Prevention and Control (ECDC) said it was “closely monitoring the situation” but stressed that the information available so far does not indicate wider transmission.

The US, which withdrew from the WHO in January, is also monitoring the situation. A US State Department spokesperson said Washington was “monitoring the situation closely” with the Centers for Disease Control and Prevention and other agencies, while urging Russia to “share accurate information quickly and openly”.

What have Russian authorities said?

Russian authorities have consistently rejected reports that Shipilova died from plague. Rospotrebnadzor, the country’s consumer rights watchdog, said she died of “pneumonia of unknown aetiology” and that tests had not found microorganisms associated with her professional activities.

Meanwhile, the health regulator said the epidemiological situation in the region was stable and that there was no basis for an epidemic in Siberia, adding that it was winding down precautionary measures. It also said Shipilova herself was vaccinated and therefore "immune to the dangerous infections with which she worked".

However, Russian authorities have not publicly established what caused Shipilova’s pneumonia. The lack of information, alongside conflicting early reports about lab exposure, fuelled by a regional governor’s initial comments suggesting this, have prompted global scrutiny.

Is there cause for worry?

There is no evidence at present of a wider plague outbreak or sustained human-to-human transmission. The ECDC said there were no reported secondary cases, while Russia has said none of Shipilova’s contacts tested positive for plague.

The WHO has so far assessed the available risk as “moderate to low” for Irkutsk, “low” for Russia as a whole, and “very low” for the WHO European region.

Public health experts say pneumonic plague has a short incubation period — around one to three days — and so far, none of the reported contacts have developed symptoms.

The immediate worry stems less from evidence of a spreading outbreak than from unresolved questions, recalling the uncertainty that marked the opening days of the covid-19 pandemic.

About the Author

Jessica has been tracking the pharmaceutical, life sciences and healthcare sector for Mint since November 2024. Based in the country's financial capital, she reports on everything to do with health and medicines. This includes corporate action, patent wars, deals, startup activity and consumer trends. She also keeps a keen eye on the ever-evolving world wellness and preventive health, which moves faster than regulation can keep up. She has a deep interest in what the future of health looks like and how science, innovation, policy and company decisions inform and impact the health of citizens. She has been a reporter for five years, working with publications like The Core and News18 prior to this, covering various sectors like automobiles, real estate, energy, sustainability and urban mobility. Jessica has a bachelor’s degree in English from St Xavier’s College, Mumbai and a postgraduate diploma in media from Sophia’s College, Mumbai. Her work is driven by a desire to decode how macro decisions and events alter and shape the lives of ordinary people. Drop her a mail or a message to discuss business scoops, exciting new medicines and inventions, or your latest wellness routine.