ATLANTA, United States — The U.S. Centers for Disease Control and Prevention says it is monitoring a suspected case of pneumonic plague in Russia after a 28-year-old laboratory worker died, but says there is no indication of a broader threat to the United States.
The woman, identified by Russian media as Darya Shipilova, worked at the Irkutsk Anti-Plague Research Institute of Siberia and the Far East, a facility that studies dangerous infectious diseases, including plague.
She died on Friday, October 2, 2026, after developing severe pneumonia.
Russian authorities have not confirmed that Shipilova had plague and say extensive testing has so far found no evidence that her death was caused by a dangerous pathogen connected to her work.
The case has nevertheless drawn scrutiny from the CDC, the World Health Organization, and other governments after Russian authorities imposed precautionary measures and placed people who had been in contact with Shipilova under medical observation.
“We are working across the U.S. government to assess developments as additional information becomes available,” the CDC said on Tuesday, according to Axios.
“At this time, there is no indication of a broader threat to the United States,” the agency said.
Despite reports describing the episode as a plague outbreak, no plague outbreak has been confirmed.
Lab Worker Dies After Developing Severe Pneumonia
Shipilova worked at the Irkutsk institute in eastern Siberia, where scientists research plague and other infectious diseases.
She became ill in late September and was admitted to a hospital in Shelekhov, near Irkutsk.
Russian authorities have described her condition as “pneumonia of unknown aetiology”.
Reports from independent Russian media suggested that Shipilova may have been exposed to Yersinia pestis, the bacterium that causes plague, during an accident at the laboratory.
Some reports alleged that a test tube containing the bacterium had broken.
Russian health authorities have denied finding evidence of such an accident.
Rospotrebnadzor, Russia’s federal public health watchdog, said an investigation at the institute found no incident involving dangerous pathogens and that expanded testing of samples from Shipilova detected no microorganisms associated with her professional activities.
Reuters reported Tuesday that Russian authorities also said no plague infections had been detected among people who had contact with her.
Russian officials have not publicly established what caused the pneumonia that killed her.
Nearly 200 People Initially Monitored
The uncertainty surrounding Shipilova’s death prompted an extensive public-health response in the Irkutsk region.
Russian media reported that about 200 people who may have had contact with her were initially placed under medical observation and subjected to repeated laboratory testing.
Several hospitals in and around Irkutsk were placed under restrictions, while dozens of Shipilova’s colleagues at the research institute were isolated as a precaution.
Rospotrebnadzor said authorities had identified the widest possible circle of contacts and arranged daily medical testing.
Tests among those contacts found two cases of Covid-19 and two rhinovirus infections, but no other dangerous infectious diseases, according to Reuters.
Russian authorities subsequently told the WHO that testing had found no dangerous pathogen among the contacts and that medical monitoring had been concluded.
“The epidemiological situation is stable and remains under monitoring,” Russian authorities said in information provided to the WHO and reported by the Associated Press.
WHO Says Wider Risk Is ‘Very Low’
The World Health Organization said it was in communication with Russian authorities as investigators sought to determine what caused Shipilova’s death.
Christian Lindmeier, a WHO spokesman, said Russian authorities had informed the organisation that no plague case had been recorded in Irkutsk.
“There is currently no indication that we are dealing with anything similar to the pandemic,” Lindmeier told the Associated Press.
The WHO assessed the risk outside Russia as “very low”.
It separately assessed the public-health risk as moderate to low in the Irkutsk area and low elsewhere in Russia, according to The Guardian.
The WHO has not sent investigators to Russia, and Russian authorities had not requested an international deployment as of Tuesday.
What Is Pneumonic Plague?
Plague is a potentially life-threatening bacterial infection caused by Yersinia pestis.
According to the CDC, people most commonly contract plague through the bites of infected rodent fleas or through contact with infected animals.
There are three principal forms: bubonic, septicemic, and pneumonic plague.
Pneumonic plague affects the lungs and is the form capable of spreading directly between people through respiratory droplets during close contact.
Its incubation period can be as short as 24 hours, according to the WHO.
Symptoms can include fever, weakness, shortness of breath, coughing, chest pain, and, in some cases, bloody sputum.
Without prompt treatment, pneumonic plague can progress rapidly and become fatal.
Unlike many viral diseases, however, plague is a bacterial infection and can be treated effectively with antibiotics when recognised early.
The CDC stresses that treatment should begin immediately when plague is strongly suspected rather than waiting for laboratory confirmation.
U.S. Calls for More Information From Russia
The uncertainty has prompted senior American officials to press Moscow for more information.
Secretary of State Marco Rubio said Tuesday that Russia had an obligation to provide greater transparency about the case.
“It’s incumbent upon Russia to obviously share more information with the world,” Rubio said during a news conference in Iceland.
“We just don’t have all the information yet,” he added.
The CDC and other U.S. agencies have been seeking additional information about Shipilova’s death.
President Donald Trump has also said the United States is prepared to assist Russia.
Trump said Tuesday that he planned to speak with Russian President Vladimir Putin about the situation and that U.S. officials were in discussions over the available information.
The CDC said it and other federal agencies would continue watching developments.
Pneumonic plague is rare, including in the United States. The disease persists naturally among some rodent populations in parts of the American West, as well as regions of Africa and Asia.
The CDC said rapid diagnosis, antibiotic treatment, and monitoring of people who may have been exposed are critical to controlling the disease.
For now, neither Russian authorities nor the WHO has confirmed that Shipilova died from plague, and there is no verified evidence of human-to-human transmission connected to her death.
