Russian health experts have detailed the transmission, symptoms, and treatment of pneumonic plague, emphasizing that zero human cases were recorded in Russia between 2017 and 2025.
Infectious disease physician Svetlana Zvontsova and virologist Petr Chumakov noted that while pneumonic plague is the most dangerous form of the disease, modern antibiotics and strict monitoring prevent any threat of an epidemic.
Pneumonic plague is an acute, highly contagious lung infection caused by the bacterium Yersinia pestis, the same organism responsible for bubonic plague. Medical specialists classify pneumonic plague under pneumonias, a broad group of infectious diseases affecting the lungs. The pathogen enters the body through respiration, or less commonly through contact with mucous membranes in the eyes, nose, or mouth, establishing an infection focus in the lungs that causes widespread inflammation, sepsis, and severe cardiovascular damage.
Without antibiotic treatment, infected patients cannot survive the condition, which causes acute respiratory failure. In severe cases involving respiratory breakdown, patients require mechanical ventilation on artificial respiration equipment.
Other forms of plague
The bacterium Yersinia pestis circulates among wild rodents and their fleas across many global regions, causing several distinct forms of illness.
Bubonic plague occurs when bacteria enter through skin cuts or infected flea bites, producing swollen, painful lymph nodes called buboes. Without treatment, bubonic plague can progress to blood sepsis. Septicemic plague occurs when bacteria accumulate directly in the bloodstream, leading to septic shock, the most severe form of sepsis. The rarest varieties include gastrointestinal plague and pharyngeal plague, which affects the throat, both of which develop after consuming contaminated meat.
Modes of transmission
Pneumonic plague spreads through inhalation via two primary mechanisms: airborne droplets from face-to-face contact when an infected individual coughs or sneezes, and airborne dust carrying bacteria from infected animals during tasks such as skinning or meat preparation. It is the only form of plague capable of direct human-to-human transmission.
Petr Chumakov, doctor of biological sciences and chief researcher at the Engelhardt Institute of Molecular Biology, said aerosol transmission requires very close contact with a patient releasing high concentrations of plague bacilli.
Chumakov explained that accidental infection in public venues such as shopping malls is practically impossible because patients with pneumonic plague suffer severe illness accompanied by extremely high fever, keeping them bedridden and limiting opportunities to infect others.
Symptoms and laboratory diagnosis
Symptoms develop rapidly, usually within 1 to 4 days after exposure, and occasionally within the first 24 hours. Patients experience fever, severe headache, general weakness, high body temperature reaching 40 to 41 degrees Celsius, acute respiratory distress, and a painful cough. The primary hallmark of pneumonic plague is a cough producing bloody sputum.
Diagnosis must be confirmed through laboratory testing using bacteriological methods, polymerase chain reaction (PCR) tests, and serological analyses. Chumakov noted that serological testing detects specific antibodies and bacterial antigens within biological samples.
Medical complications
Without prompt intervention, pneumonic plague inflicts extensive damage across multiple organ systems. Complications include pulmonary edema, where fluid accumulates in the lungs to block breathing, and pleural damage, involving inflammation of the lung lining that causes acute pain.
Patients may develop blood stasis and blood clots, leading to vessel blockages, alongside lung tissue necrosis where sections of the lung die. Endothelial damage to blood vessel linings causes circulatory disruption and internal hemorrhaging.
Other severe outcomes include acute cardiovascular failure, acute renal failure preventing kidney filtration, and infectious-toxic shock resulting from bacterial toxins that cause sudden pressure drops. Tissue destruction at fingertips can lead to gangrene, turning fingers black and numb, while disseminated intravascular coagulation (DIC) syndrome causes widespread clotting followed by severe bleeding.
Antibiotic treatment protocols
Immediate medical care is mandatory because untreated pneumonic plague is consistently fatal. Responsive to antibiotics, early diagnosis saves lives and prevents complications.
Chumakov noted that the plague bacillus remains highly sensitive to a wide array of antibiotics, allowing doctors to arrest the infection effectively if treatment begins early. Standard antibiotic therapy lasts at least 10 to 14 days, utilizing medications such as ciprofloxacin, levofloxacin, moxifloxacin, gentamicin, and streptomycin. Survival rates increase significantly when antibiotic administration starts within the first 24 hours of infection. Supportive care, including supplemental oxygen, is provided to assist patients experiencing severe breathing difficulties.
Vaccine history and prevention
Plague vaccines have existed since the 19th century, following the initial vaccine developed by bacteriologist Vladimir Khavkin, who tested it on himself in 1897. Modern vaccines derived from Khavkin's work effectively protect against bubonic plague.
The World Health Organization does not recommend general population vaccination, advising it exclusively for high-risk personnel, such as laboratory staff continuously handling live pathogens. Individuals exposed to infected contacts receive preventive antibiotic courses to forestall infection.
Historical pandemics and global cases
Genetic research on ancient Yersinia pestis DNA shows the pathogen shared a common ancestor with Yersinia pseudotuberculosis and evolved in isolation without exchanging genes with other bacteria. During the Bronze Age, the bacterium acquired a gene enabling transmission via external parasites such as fleas and lice while retaining its ability to infect hosts through contaminated food or water.
Three historical pandemics have been documented since the 5th century AD: the Justinian Plague from 541 to 750 AD, the Black Death from 1346 to 1353, and the third pandemic that began in China in 1855 and concluded in 1959.
World Health Organization data shows 5,626 registered plague cases globally between 2016 and 2025, resulting in 516 deaths, representing a 9.2 percent mortality rate. Between 2019 and 2025, most cases were reported in the Democratic Republic of the Congo and Madagascar. In 2025, only 67 human cases were reported worldwide across four nations: the Democratic Republic of the Congo with 41 cases, Madagascar with 18 cases, Mongolia with 3 cases including 1 death, and the United States with 1 case.
Pneumonic plague remains rare among overall cases. The last documented human-to-human transmission of pneumonic plague in the United States occurred in 1924 in Los Angeles, while the most recent US case in July 2025 involved an Arizona resident infected by sick cats without secondary human spread.
Epidemiological status in Russia
Russia recorded zero human plague cases between 2017 and 2025, with infections restricted to wild animals within three natural foci in the Caucasus, Altai, and Tuva mountains. Natural foci exist worldwide on every continent except Antarctica and Australia. Across Russia, health authorities monitor 11 natural foci where Yersinia pestis circulates continuously among wild rodents and fleas independent of humans.
Tense epizootic activity, marked by active bacterial spread among animals, was recorded in five specific areas: the Caspian Sand Focus, Altai Mountain Focus, Tuva Mountain Focus, Eastern Caucasus High-Mountain Natural Focus, and Central Caucasus High-Mountain Focus. The remaining six monitored areas comprise the Volga-Ural Sand Focus, Terek-Sunzha Low-Mountain Natural Focus, Dagestan Plain-Foothill Natural Focus, Transbaikal Steppe Focus, Caspian Northwestern Steppe Focus, and Volga-Ural Steppe Focus.
Svetlana Zvontsova, infectious disease doctor at ID-CLINIC, said that average citizens face minimal infection risk because plague does not spread en masse like influenza or coronavirus, but requires direct contact with infected wildlife or parasites in specific locations. Key animal reservoirs in Russia include gophers, gerbils, common voles, Altai marmots, Mongolian pikas, and Daurian pikas, alongside rats globally.
Containment and prevention measures
Disease control in Russia is managed by the Anti-Plague Service of Rospotrebnadzor, which monitors natural foci, exterminates rodents and fleas, isolates diagnosed patients, observes contacts, provides prophylactic antibiotics to risk groups, and conducts health screenings for hunters, foresters, and geologists.
Research facilities housing live pathogens across major Russian regions maintain multi-layered containment protocols, including sealed isolator boxes and specialized protective suits. Zvontsova said that emergency procedures for laboratory accidents, such as a broken test tube, require immediate isolation of the box and application of chloramine to destroy the pathogen.
Factors preventing modern epidemics
Zvontsova detailed three primary reasons why a modern plague epidemic is impossible. First, as a bacterial infection, plague responds effectively to antibiotics, rendering even pneumonic cases curable when treated early.
Second, transmission mechanisms are inefficient for mass dissemination, as bubonic spread requires high rodent populations, vector fleas, and unsanitary conditions that do not exist in modern cities with central water systems. Third, continuous surveillance of natural foci combined with short incubation periods allows rapid containment of isolated cases.
Targeted preventive measures focus on high-risk groups, including laboratory personnel handling pathogens, field workers in natural foci such as hunters, foresters, and geologists, and close contacts of infected individuals.
