The Russian Scare: Pneumonic Plague?
“Known as the “Black Death” in the 14th century, [the plague] killed more than 50 million people in Europe. While antibiotics have made the infection more manageable, it remains present on every continent except Oceania.”
Jen Christensen, “What is pneumonic plague and how dangerous is it?”, CNN Health, October 5, 2026
“For a disease that doesn’t kill very many people in modern times, it certainly has terrible branding.”
Anna Gibbs, “The Real Reason the Russian ‘Plague’ Case Is Worrisome Has Little to Do with The Actual Plague,” Slate, October 8, 2026.
Plague is back in the headlines, and this time it’s the pneumonic (lung) form that has grabbed people’s attention. On October 4, 2026, news broke that a 28-year-old woman, a laboratory technician at the Irkutsk Research Anti-Plague Institute in Shelekhov, Siberia, died after developing severe pneumonia. Russian media and regional officials pointed to a suspected plague exposure. But, Rospotrebnadzor, Russia’s federal health agency, has not confirmed plague, describing the illness instead as pneumonia of unknown cause and denying that any accident with pathogens occurred at the institute.
Nearly 200 people who came into contact with the woman, however, were reportedly placed under observation. As of this writing, Russian officials say these contacts have shown no signs of any illness. And although Russia has provided no additional information, on October 6, 2026, a spokesperson for the World Health Organization (WHO), said that there was no sign of a wider outbreak.
In my Germ Gems post two years ago, “The Bubonic Plague—Down But Not Out,” I provided an overview of plague but only mentioned the pneumonic form in a single sentence. As it now appears it deserves more attention, I am revisiting pneumonic plague in this post.
Plague (a recap). Plague is a bacterial infection caused by the bacillus Yersinia pestis. (It is named for Alexandre Yersin who discovered the bacillus in 1894.) It is zoonotic—an infection transmitted from animals to humans. Rats are the most common carriers of the disease. But many other rodents, and, in some cases, even rabbits or domestic animals (dogs and cats) can carry the disease. The “carrier” does not, however, spread the disease directly to humans.
In 1898, the French physician Jean-Paul Simond determined that the disease was a vector-borne infection, that is, transmitted from rodents to humans via flea bites. (Recent studies suggest that human body lice can also harbor Y. pestis.) First the rat (or another animal) gets infected and is bitten by a flea living on the rat thereby infecting the flea. The flea then jumps from the rat to a human, bites the human and transmits the infection. While the bacterium is the culprit, the flea—the intermediary—is the real offender.
There are four different forms of plague: bubonic, septicemic, pharyngeal, and pneumonic. Each depends on where the body is infected with Y. pestis. Common symptoms for all types of plague include fever, chills, headaches and body aches, weakness and fatigue, dizziness, nausea, vomiting and diarrhea. Other symptoms are dependent on the specific form of plague.
Bubonic plague –where the infection travels to the lymph nodes—is the most common form. Its name is derived from the Greek Word Boubon, referring to enlarged lymph glands call buboes, one of the most evident symptoms of the disease. Bubonic plague can progress to septicemic plague. According to the European Centre for Disease Prevention and Control, the case fatality rate for untreated bubonic plague ranges from 40-70%.
Septicemic plague occurs when Y. pestis invades the bloodstream. This can destroy tissues and lead to organ failure. In addition to the symptoms common to all forms of plague listed above, other symptoms for septicemic plaque include abdominal pain and bleeding from the nose, mouth, or rectum or under the skin. Historically and clinically, septicemic plague is considered almost always fatal without rapid and targeted antibiotic therapy.
Pharyngeal plague is a pestis infection of the throat and oropharynx. It is a rare form of the plague and develops from eating meat from an infected animal. (Saeed, A., et al., “Plague from Eating Raw Camel Liver,” Emerging Infectious Diseases, September 2005).
Focus on pneumonic plague. Pneumonic plague is also a rare form of the infection and occurs when particles of Y. pestis lodge in the lungs, causing severe pneumonia. It is the only form of the plague that spreads directly from person-to-person.
A person can contract the pneumonic plague from another person by inhaling infectious respiratory droplets—tiny liquid particles of saliva, mucus and fluid from the lungs, loaded with Y. pestis, that are sprayed into the air when someone with pneumonic plague coughs or sneezes. (Droplets from infected animals can also transmit the bacterium.) Because droplets are relatively large and heavy, don’t hang in the air for long and don’t travel far, person-to-person transmission of pneumonic plague requires close, direct contact with an infected person. It is highly unlikely that one would contract pneumonic plague by just being in the same room with an infected person; it is not that contagious.
Symptoms can begin within 24 hours of infection and progress rapidly. Without treatment, pneumonic plague is nearly 100% fatal. But like all other forms of plague, pneumonic plague can usually be successfully treated with antibiotics and patients that receive antibiotic therapy within 24 hours of infection have the best chance of surviving.
In the U.S., first-line drugs to treat plague include gentamicin and the fluoroquinolones—levofloxacin, ciprofloxacin and moxifloxacin—given for at least 10-14 days. People who have close contact with a plague patient are also given a seven-day course of preventative antibiotics. Currently, there is no plague vaccine approved for use by the U.S. Food and Drug Administration.
Lack of transparency. Russia was less than transparent about the cause of the death of this lab worker. Initially, the WHO did not receive a formal notification of the event and had to request additional details from Russia. The U.S. state department had to send Russia a confidential diplomatic communication—a demarche—warning Moscow that failure to disclose details ran counter to international health obligations. Urging Russia to be transparent, WHO chief Tedros Ghebreyesus said: “Timely, complete and transparent information sharing under the International Health Regulations is essential to clarify conflicting reports and enable an accurate assessment of potential health risks.” (Harding, L., “Plague epidemic risk in Russia low after death of lab technician, WHO says,” The Guardian, October 6, 2026).
As of this writing, no one knows (or is disclosing) whether the lab worker died from pneumonic plague or not. But what we do know is that plague is not much of a problem today. It is treatable with very effective antibiotics when treatment is started promptly and these antibiotics can also be taken prophylactically if one comes in contact with an infected person. Moreover, plague is not that contagious. Even the pneumonic plague, the only form that can be transmitted from person-to-person, requires close direct contact. So, the bottom line is the risk of pneumonic plague spreading to the U.S. from this event—if, indeed, it was the plague—is essentially nil.
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