Russia Quarantines Hundreds After Death at Siberian Plague Research Institute

Between several dozen and roughly 200 people have been quarantined in Russia's Siberia region after a female worker at the Irkutsk Plague Research Institute fell ill and died under circumstances that have not been fully disclosed.

According to the Russian news outlet People of Baikal, the woman may have contracted pneumonic plague after a test tube broke, and then died. Russian officials later said post-mortem tests showed no signs of plague and insisted the situation was under control.

What happened at the Irkutsk research institute

On Monday, Russian media reported that a 28-year-old female worker named Darya Shipilova, who worked at the Irkutsk Anti-Plague Research Institute of Siberia and the Far East, had died the previous week with suspected pneumonic plague.

According to some reports, Shipilova fell ill while working on September 30 and died two days later at a hospital in the nearby town of Shelekhov. Some sources suggested an accident may have occurred in the laboratory, but this has not been officially confirmed.

About 200 people who had contact with the woman have been quarantined. Part of the hospital where she died was also sealed off, and a nearby aluminium plant asked workers to wear masks.

Anna Popova, head of Russia's public health watchdog Rospotrebnadzor, flew to Irkutsk four days ago to meet Governor Igor Kobzev and other officials.

In a statement cited by TASS news agency, Rospotrebnadzor said Irkutsk regional authorities had found two cases of COVID-19 and two cases of rhinovirus among those who had contact with the researcher. No other infectious disease cases were recorded.

By Monday, Russian officials said they had found no evidence that the woman's illness was caused by any pathogen she had worked with, and that the situation was under control.

Governor Kobzev said the woman died of "pneumonia of unknown cause", stressing that no further employees of the Anti-Plague Institute had sought medical care in recent days. He said all those who had contact with the victim had been identified, tested and placed under medical supervision.

What is plague and how does it spread?

Plague is a severe, potentially life-threatening infection caused by the bacterium Yersinia pestis. From 1346 to 1353, bubonic plague – one of the three forms of the disease – became known as the "Black Death" and caused one of the deadliest pandemics in history across Eurasia and North Africa. An estimated 30-60% of Europe's population died in that outbreak.

Pneumonic plague is less common than the bubonic form but is a serious infection that can spread from person to person.

The plague bacterium is carried by small wild mammals and the fleas that parasitise them. In Siberia, where the disease is endemic, Russians rarely contract plague, although cases still occur annually elsewhere in the world, especially in Africa.

According to the US Centers for Disease Control and Prevention (CDC), plague has been recorded in people of all ages, from infants to those over 90. Half of cases occur in people aged 12 to 45. Both men and women can be infected, although historically the disease was more common in men.

There are three main forms of plague, affecting different parts of the body: bubonic, septicaemic and pneumonic. According to the World Health Organization (WHO), bubonic plague is the most common clinical form, with symptoms including swollen, painful lymph nodes known as "buboes".

The septicaemic form attacks the blood, while the pneumonic form affects the lungs. WHO describes these two as the "less common but more serious" forms of plague.

A fourth form, pharyngeal plague, is very rare and can be contracted by eating infected meat.

According to the Cleveland Clinic in the US, besides swollen lymph nodes in the bubonic form, infected people may have symptoms such as fever and chills, headache and body aches, weakness and fatigue, dizziness, nausea, vomiting and diarrhoea.

If left untreated, plague can cause complications such as meningitis, tissue necrosis and loss of limbs due to gangrene, respiratory failure and organ failure. The bubonic form has a mortality rate of 30-60%. The pneumonic and septicaemic forms are both fatal if not treated within one to six days, according to WHO. However, if detected early, all forms can be treated with antibiotics.

Plague usually spreads through the bite of a flea carrying the pathogen from rodents, but it can also be transmitted from person to person. According to the CDC, people can also contract the disease through contact with sick pets, especially cats.

The main transmission routes include: flea bites – including from dead infected rats or fleas that have bitten infected rats; direct contact with the tissues or body fluids of infected animals; and respiratory droplets – droplets of fluid coughed out by a person or animal with pneumonic plague can hang in the air and be inhaled by others. The CDC says this route requires direct, close contact with a person or animal with the pneumonic form, and is the only way the disease spreads from person to person.

According to the CDC, the last recorded case of person-to-person transmission of pneumonic plague was in 1924. However, there have been more recent cases of transmission from sick cats to humans. Cats are particularly susceptible to plague and can become infected by eating infected rodents; infected cats are at risk of transmitting infectious droplets to their owners or veterinarians.

Where does the disease exist?

Ian Jones, professor of virology at the University of Reading, told the AP news agency that "plague carries a huge history and is still present in many parts of the world, including Russia".

According to the Cleveland Clinic, the world records about 1,000 to 2,000 cases of plague each year. The disease is endemic in Siberia – where the earliest known prehistoric human outbreak was recorded. Besides Russia, plague is also endemic in several other countries. From 2019 to 2025, most new cases recorded by WHO occurred in the Democratic Republic of Congo and Madagascar.

Some rare cases have appeared elsewhere. In July 2025, a man in Arizona who worked with cats died of pneumonic plague – the first such death since 2007.

Earlier, a major outbreak of bubonic plague occurred in Los Angeles in 1924-1925, after the disease was first recorded in the US in 1900, carried by infected rats on steamships. Since then, bubonic plague has accounted for 80% of an average of seven cases per year in the US. The CDC says most of these cases occur in northern New Mexico, northern Arizona, southern Colorado, California, southern Oregon and western Nevada.

Why has the incident raised global concern?

Although Russian officials stressed that post-mortem tests found the woman did not have plague, the incident has sparked global concern. Some authorities have called on Russia to clarify further what happened to the laboratory worker.

In Washington, US President Donald Trump said he was monitoring the situation with concern and that the US was ready to help, although he said he had not discussed the matter with Russian President Vladimir Putin. "It's a dangerous disease. It's a disease we used to be able to control, but somehow these bacteria have become stronger and smarter. They're like an army," Trump told reporters outside the White House.

US Secretary of State Marco Rubio said on Monday he did not believe there was reason for alarm, but stressed that the US was closely monitoring the incident, aware that the disease "can spread quickly" despite quarantine and other public health protocols.

Should the world be worried?

On Monday, Kremlin spokesman Dmitry Peskov said the public and media should follow official statements from Rospotrebnadzor rather than "rumours or speculation".

Malick Gibani, associate professor of clinical bacteriology and vaccinology at Imperial College London, said in a statement to the media: "It's difficult to comment definitively when the available information is still relatively limited."

"Based on the reports, it appears there was an initial suspected case and contacts have been quarantined. If laboratory exposure to a potentially dangerous pathogen occurred, the usual procedure is to assess the risk to those who may have been exposed and the nature of their contact," he said.

He said those considered at risk may be monitored and, where appropriate, may be tested, isolated or given post-exposure prophylaxis with antibiotics. "I think it's important that we see how the incident develops, and ideally that there is good information exchange between public health officials and the wider global health community."

According to Gibani, the incident highlights the need for awareness of ongoing outbreaks of serious bacterial pathogens, and demonstrates the need to invest in biosafety, particularly to prevent biological risks. This could include developing medical countermeasures such as better diagnostic tests or vaccines.