The death of a Russian laboratory technician at a plague research center in Siberia has sparked international concern and speculation about whether a laboratory leak of the rare infectious disease occurred.
Russian officials initially linked her death to plague, but they now deny a connection despite independent media reports of a local quarantine.
So, what happened to this woman? How worried should the public be?
What do we know?
Daria Shipilova, 28, works at the Siberian and Far East Anti-epidemic Research Institute. She was admitted to the hospital at the end of September this year.
She died three days later in the town of Shelekhov on the outskirts of Irkutsk.
Reports said she died on October 2, but the BBC has not been able to confirm this.
Hospitals were quarantined, a mask mandate was implemented at a local aluminum factory, and a large public event in Irkutsk was canceled.
On Friday, the region's governor, Igor Kobzev, announced that Russia's chief health officer had arrived in Irkutsk to investigate a "suspected case of particularly dangerous infection."
Authorities are monitoring people who came into contact with Shipilova. According to the Izvestia newspaper, some 197 people are under medical observation.
On the same day, the governor of the neighboring Republic of Buryatia announced that the laboratory worker died of plague.
It also began to spark speculation about a possible laboratory leak at the Institute of Epidemic Prevention, with an unconfirmed report by a local journalist that the late researcher contracted the disease after breaking a test tube.
How did this narrative change?
Russia's consumer rights protection and public health watchdog (Rospotrebnadzor) tried to retract these claims.
The agency said this week that the lab worker, whose name it has not released, died of pneumonia of unknown cause and that tests "did not identify microorganisms associated with his occupational activities."
After the announcement, a pro-government federal news outlet removed five posts mentioning possible plague cases.
Separately, authorities in the city of Baikalsk also deleted a message advising people not to travel to the town of Serekhov.
However, just when the authorities seemed to be coordinating the release of information to downplay the situation, the local independent news website People of Baikal quoted sources as saying that at least four hospitals in Irkutsk had been closed for three weeks for quarantine due to the epidemic.
This news has not yet been officially confirmed.
At the same time, the BBC Russian team learned that the Irkutsk Plague Prevention Institute plans to hold an international plague control conference in late October, which will be attended by scientists from China, Mongolia and several former Soviet countries.
The BBC has contacted the institute to confirm whether the meeting will go ahead as planned.
What is plague?
Yersinia pestis, a bacterium that killed nearly half of Europe's population in the 14th century, was known as the Black Death. It causes a disease in animals found on all continents except Oceania, including in rodents such as marmots in the Buryatia region of Russia.
People can become infected through flea bites, contact with body fluids or contaminated materials, or inhalation of respiratory particles.
The World Health Organization (WHO) says pneumonic plague has a very short incubation period - sometimes as little as 24 hours - and can be fatal if not diagnosed and treated promptly.
Symptoms include shortness of breath and coughing, and the sputum is often bloody.
But Russian science journalist Irina Yakutenko emphasized that regardless of the cause of death of laboratory workers, the risk of a plague epidemic is small because the conditions required to sustain an outbreak do not exist in developed countries.
"Basic antibiotics are very effective against plague because the disease is now so rare that there is no chance of widespread resistance developing," she told the BBC Russian podcast.
international community reaction
A WHO spokesperson told news agency Politico that the WHO has been in contact with Russian authorities to assess the situation and its impact on international public health.
In addition, experts from Europe's infectious disease regulator ECDC are also closely monitoring developments, according to a European Commission spokesperson.
U.S. President Donald Trump said on Monday that the United States was "paying close attention" to reports of possible plague cases in Russia.
He also suggested the United States was ready to help control the outbreak but said the matter had not yet been discussed with the Kremlin.
U.S. Secretary of State Marco Rubio also expressed the same view. "We encourage Russia to be transparent and share more information with the world so that we can all respond accordingly," Rubio told a news conference in Reykjavik, the capital of Iceland.
On Tuesday, Kremlin spokesman Dmitry Peskov welcomed Trump's offer of support.
"It's always nice to have someone to help," Peskov told BBC Russian editor Steve Rosenberg.
He added that only official information about the situation in Irkutsk can be trusted.
What opinions are appearing on the Internet?
There are many conflicting reports circulating on social media in Russia and abroad.
The BBC has discovered at least five Instagram accounts posting unconfirmed claims claiming a second victim.
The accounts, which have nearly 169,000 followers combined, posted nearly identical messages in Russian, claiming that a man named Viktor Naklonenny, allegedly a colleague of Darya Shipilova, was also dead.
However, a source close to the Russian Federal Service for Consumer Protection and Welfare did not confirm these reports.
The BBC has contacted the agency for comment. The Siberian and Far Eastern Epidemic Prevention Institute declined to comment.
These unsubstantiated claims were subsequently reported by a number of international media outlets, including the UK's Daily Mail, which said the information came from "local media" in Russia.
The posts sparked mixed reactions online, with some users expressing concerns about public health measures and others accusing the accounts of spreading misinformation.
Although it is more lethal if left untreated, plague is unlikely to kill as many people as COVID-19 because antibiotics can control it.
