United States officials are closely monitoring the situation after reports that the death of a laboratory technician in Russia may be linked to pneumonic plague.
The deceased technician, a 28-year-old woman, worked at the Irkutsk Antiplague Research Institute of Siberia and the Far East. The facility was established in the 1930s as an anti-plague body and later expanded its operations to include other highly dangerous diseases, reports The Washington Post.
According to Russia’s public health agency, Rospotrebnadzor, the technician died after being diagnosed with pneumonia of “unknown” origin.
US Secretary of State Marco Rubio told reporters on Monday morning that Russian officials had shared preliminary information about the infected laboratory worker. He said there were also concerns that additional Russian citizens could be affected.
Rubio noted that travel between the US and Russia remains very limited. However, he warned that an escaped pathogen could spread quickly. He stressed that the development was not currently a cause for alarm, while US authorities continue to monitor the situation closely.
If Russian authorities confirm that pneumonic plague caused the death, they are required to report the finding to the World Health Organization (WHO).
However, official reporting could be delayed as Russian officials conduct laboratory tests and tissue sampling to verify the presence of the Yersinia pestis bacteria.
Ashish Jha, who helped lead the White House’s pandemic response under the Biden administration, stressed the importance of transparency from Russian authorities over the incident.
How plague spreads
Plague is an infectious disease typically found in small mammals and their fleas. It can spread to humans through flea bites, direct contact with infectious bodily fluids or inhalation of respiratory droplets.
The disease is caused by the Yersinia pestis bacteria. Its three main clinical forms — bubonic, pneumonic and septicemic — can be treated with antibiotics, particularly when detected early.
Historically known as the “Black Death”, plague claimed more than 50 million lives in 14th-century Europe. Today, it can be managed through antibiotic treatment and standard precautions.
Pneumonic plague is the most virulent and contagious form of the disease. It infects the lungs and can spread directly between people through respiratory particles.
According to the WHO and the Centers for Disease Control and Prevention (CDC), symptoms can develop rapidly within 24 hours. They include fever, headache, weakness, shortness of breath, chest pain, cough, and bloody or watery mucus.
Without prompt diagnosis and treatment, pneumonic plague is invariably fatal. However, recovery rates are high when treatment begins within 24 hours of symptoms appearing.
Bubonic plague is the most common form globally. It is primarily transmitted through infected flea bites and causes swollen lymph nodes known as “buboes”. The WHO estimates its case-fatality ratio at 30 to 100 per cent.
Septicemic plague occurs when the bacteria rapidly multiplies in the bloodstream. It can cause organ failure, tissue damage, respiratory distress, chills, abdominal pain, shock and tissue necrosis.
Like pneumonic plague, untreated septicemic plague is always fatal.
Previous cases in the US
In the United States, plague bacteria are endemic among rodent populations in northern Arizona. Eight human cases were recorded there between 2000 and 2024.
In July 2025, Arizona recorded its first pneumonic plague fatality since 2007. The victim was a young man who had been exposed to sick cats.
He sought hospital care after experiencing two days of abdominal pain, chest pain and a dry cough. Doctors initially suspected hantavirus or bacterial pneumonia.
Despite receiving antibiotics and intensive oxygen therapy, he died less than eight hours after admission.
Following his death, health officials gave a seven-day course of ciprofloxacin to 46 potential contacts, including family members, co-workers and hospital staff. None of them became ill.
