Russia Laboratory Death Raises Plague Concerns, but CDC Says U.S. Risk Is Very Low

The mysterious death of a woman in Russia following a laboratory accident has raised concerns about a possible plague outbreak. However, the chances of the disease spreading more widely remain very low, according to the Centers for Disease Control and Prevention (CDC).

The CDC said Tuesday afternoon that the circumstances surrounding the incident remain unconfirmed and that there is “no indication of a broader threat to the United States” at this time. Read the CDC’s statement on X.

“We are working across the U.S. government to assess developments as additional information becomes available,” the agency said. “CDC and our interagency partners are ready and will continue to closely monitor the situation.”

What happened at the Russian laboratory?

Last week, a young researcher died of severe pneumonia of unknown cause after breaking a test tube at the Irkutsk Anti-Epidemic Institute in Siberia. The hospital where she was treated before her death was isolated, according to reports. Her colleagues at the laboratory were also isolated, Radio Free Europe/Radio Liberty reported.

World Health Organization spokesman Christian Lindmeier told reporters in Geneva on Tuesday that the organization was in contact with Russian authorities. Based on the information currently available, the WHO said the public health risk to the general population is very low.

“I think that’s the correct assessment,” said Gigi Gronvall, an immunologist and senior research scientist at the Johns Hopkins Center for Health Security. “Right now, we don’t know anything about anything.”

Russian authorities report no signs of spread

Russian authorities said contact tracing had found no signs that the dangerous pathogen had spread, according to AP.

Although plague was infamous for killing millions of people in medieval Europe, it is rare today. The disease is caused by the plague bacterium, which is found in wild rodents and their fleas in many parts of the world. People can become infected through the bite of an infected flea and, in some cases, through direct contact with an infected animal.

Antibiotics can cure plague, but treatment should begin as soon as an infection is suspected.

What is pneumonic plague?

Pneumonic plague occurs when a person inhales infectious droplets containing the bacteria. In July 2025, an Arizona man died of pneumonic plague after contact with an infected cat.

Pneumonic plague can also spread from person to person through respiratory droplets during close contact. However, human-to-human transmission is rare, with the last reported outbreak occurring in Los Angeles in 1924. Because of the possibility of transmission, the CDC says it is important to identify and treat cases quickly.

“If we know that someone has been exposed to the virus, or even if we suspect that someone has been exposed to the virus, we can immediately start giving them antibiotics to prevent them from getting sick and to avoid the continued spread of the disease,” said Rutul Dalal, an infectious disease physician at Penn State Health St. Joseph Medical Center.