The death of a Russian lab worker, possibly from pneumonic plague, has sparked concern around the world.

A worker at the Irkutsk Anti-Plague Research Institute of Siberia and the Far East in Shelekhov died of an unknown pneumonia, Forbes reported

Russian authorities have reportedly quarantined 200 lab workers as a result, according to the publication.

Some Russian officials suggested the woman may have died of plague. A World Health Organization official said the risk to the general population “appears to be low,” Forbes reported.

Pneumonic plague is a virulent form of plague that can be passed from human to human.

Here’s what to know:

What is pneumonic plague?

Plague is an infectious disease caused by the bacteria Yersinia pestis, usually found in small mammals and their fleas, WHO said.

There are three basic kinds of plague: bubonic, pneumonic and septicaemic.

Bubonic plague, the most common, is spread by the bite of infected fleas. Septicaemic plague can develop when bacteria multiply rapidly in the bloodstream and can develop from the other two kinds of plague. It is fatal if left untreated.

Pneumonic plague is a lung-based plague considered the most virulent form of plague, WHO said. It can be passed from human to human, unlike the other two forms. Recovery rates are high if it is treated within 24 hours, but it’s otherwise often fatal.

Known as the Black Death, plague was responsible for more than 50 millions deaths in Europe during the fourteenth century.

How common is pneumonic plague?

Pneumonic plague is rare. In recent decades, an average of seven cases of plague are reported in the United States each year, the U.S. Centers for Disease Control and Prevention said.

More than 80% are cases of bubonic plague, the agency said. Person-to-person spread of plague has not been documented in the United States since 1924.

Who is at risk for pneumonic plague?

People who have close, face-to-face contact with an infected person or animal coughing respiratory droplets, or individuals with untreated bubonic or septicemic plague whose infection spreads to the lungs are at risk for pneumonic plague, the CDC said.

What are the symptoms of pneumonic plague?

The Cleveland Clinic says symptoms of pneumonic plague, which can appear in less than 24 hours from infection, can include:

•Fever

•Chills

•Headaches and body aches

•Weakness and fatigue

•Dizziness

•Nausea, vomiting and diarrhea

•Abdominal pain and bleeding from your nose, your mouth or under your skin

•Shortness of breath, chest pain, cough and bloody or watery mucus

What are the complications of pneumonic plague?

Complications of plague can include organ failure, tissue damage, respiratory distress and bleeding under the skin, WHO said. It can lead to death unless quickly treated.

When should you see a doctor about pneumonic plague?

Get immediate care if you have a sudden high fever and seek immediate emergency care if you have a sudden high fever or other symptoms and you live in an area that has had cases of plague, the Mayo Clinic advised.

How does pneumonic plague spread?

While bubonic plague is most often transmitted by bites from infected fleas, pneumonic plague can spread through bacteria-containing droplets in the air from an infected person, Medical News Today said.

Pneumonic plague is the only form of plague that can spread from human to human.

How can you prevent pneumonic plague?

Medical face masks can reduce the spread of droplets containing plague bacteria, the National Special Pathogen System said. Immediate antibiotics after exposure also can help protect against pneumonic plague.

How do you treat pneumonic plague?

Pneumonic plague is treated with powerful antibiotics, preferably within 24 hours of the first symptoms, the Cleveland Clinic said. Recovery may take a week or two.

Pneumonic plague is always fatal unless treated, the clinic said.

______

©2026 The Sacramento Bee. Visit sacbee.com. Distributed by Tribune Content Agency, LLC.