US delivers démarche to Russia over Siberia plague lab death

WHO assesses pneumonic plague risk outside Russia as very low

The United States has delivered a confidential diplomatic communication to Russia warning that Moscow’s failure to disclose details about the death of a Siberian plague lab worker violates international health obligations, U.S. officials said. The démarche adds another source of tension between Washington and Moscow as the Trump administration seeks to improve ties with Russian President Vladimir Putin and make progress on efforts to end the war in Ukraine.

Russia has provided the U.S. with little information about the episode, which has stirred fears that an infectious disease might spread inside Russia and beyond its borders, American officials said. Secretary of State Marco Rubio said Tuesday that the information shared by Moscow was “still quite limited” but made no reference to the private diplomatic communication.

“We encourage Russia to be transparent and share more information with the world so that all of us could react accordingly and appropriately,” Rubio said while in Iceland to discuss security cooperation in the Arctic. “Maybe there’s nothing there. Maybe it’s bigger than we thought. We don’t know.” A State Department spokesperson said the department has officially requested additional information from the Russian government and is in official communication with other countries to share information.

“We’re watching it very closely, hour by hour,” Rubio said. “We have multiple agencies, not just in the U.S. but internationally, that are watching it.”

Four days after the worker’s death, Russian authorities still have not disclosed the exact cause, saying only that she died of pneumonia. The woman has been identified in local media reports as Daria Shipilova. The lack of detail has fueled speculation that her lab work may have exposed her to a deadly pathogen and raised questions about whether Russia has done enough to contain what authorities have called an infectious disease.

Under the 2005 International Health Regulations, countries are required to notify the World Health Organization within 24 hours of an event that could become an international public health emergency. The pact also requires signatories to provide detailed updates, including lab results and measures being taken to contain the threat. While Moscow has provided some information to the WHO, it has yet to answer basic questions about the case, including what tests were run.

The governor of Irkutsk, Igor Kobzev, said earlier in the week that specialists had carried out extensive laboratory analyses of the woman’s body and found no “microorganisms connected to her professional activities.” The WHO said Tuesday that the possible pneumonic plague case in Russia poses a “very low” risk outside the country. The Trump administration withdrew the U.S. from the WHO earlier this year in part because of the U.N. health body’s handling of the Covid pandemic.

Hayley Severance, a former policy adviser at the Defense Department and an expert on global biological policy at the Nuclear Threat Initiative, a nonprofit security organization, said Russia should share more information about the episode. “As much transparency as possible will help calm fears of further international spread,” Severance said.

Russia’s consumer watchdog agency, which oversees the lab where Shipilova worked, has said her death was pneumonia due to “an unknown cause.” Since her infection, contacts of the woman have been put under medical observation. On Tuesday, authorities said that among her contacts there has been evidence of Covid-19 and a cold virus.

The State Department says Russia still has a germ weapons program that violates the Biological Weapons Convention. In a 2025 report, the State Department said: “Russia inherited the past offensive program of biological research and development from the Soviet Union. The U.S. assesses that the Soviet program was absorbed, not dismantled, by the Russian Federation, and that the program has continued and evolved.” In 1979, an accident at a Soviet facility led to an anthrax outbreak in Sverdlovsk, Russia, now known as Yekaterinburg. Soviet officials initially said the illnesses were the result of contaminated meat. Boris Yeltsin, who served as Russia’s first president after the breakup of the Soviet Union, later told a Russian newspaper that a “military development” led to the outbreak.

A lack of trust in Russian public health institutions has triggered fear of a potential plague outbreak among residents in the Siberian region of Irkutsk, near the border with Mongolia. Neighboring Central Asian countries have likewise boosted health safety measures at borders and airports.

While there are parallels between Russia’s reluctance to share information on the incident in Siberia and China’s lack of transparency on the Covid-19 outbreak, officials said there is no indication the Russian case could trigger an outbreak as contagious as the Covid pandemic.

President Trump said Monday that the U.S. could help with the situation. Russia’s consumer watchdog agency responded by saying it would be willing to help the U.S. with its outbreaks of measles.

The bacterium Yersinia pestis, which can cause pneumonic and bubonic plague, has been identified from time to time in Siberia, linked to exposure to vermin. The anti-plague institute in Irkutsk was established in 1934, under Soviet leader Joseph Stalin, to control cases of plague, according to its website, and has since conducted work to monitor, research and develop treatment for other serious infectious diseases, including cholera, anthrax and brucellosis. The institute took part in a bilateral training exercise with China earlier this year against the potential outbreak of an infectious disease.