The plague did not end with the Middle Ages, as many probably think. The dangerous disease has not completely disappeared, as confirmed by the current case from Siberia. What should we know?
Reports of a possible case of pneumonic plague in Siberia have once again drawn attention to the disease that many consider to be part of the distant past. However, the plague has not completely disappeared. Although it is rare today and is successfully treated with antibiotics, new cases are registered annually in certain regions of the world.
A form of the plague, not a separate disease
Pneumonic plague is not an independent disease. It is one of the three main forms of the infection caused by the bacterium Yersinia pestis. The same pathogen causes bubonic and septicemic plague. They differ in which part of the body the infection affects. In bubonic plague, the bacteria enter the lymphatic system and cause inflammation of the lymph nodes. If the pathogen enters the blood, the septicemic form develops. When the infection affects the lungs, it is called pneumonic plague.
The pulmonary form can occur both as an independent disease after inhalation of bacteria, and can become a complication of bubonic or septicemic plague if the infection is not stopped in time.
Why is pneumonic plague the most worrying
Of the three forms of the disease, the pneumonic form is considered the most dangerous from an epidemiological point of view. Bubonic plague is usually transmitted through the bites of infected fleas and is extremely rarely spread between people. However, the pneumonic form can be transmitted by airborne droplets - through the smallest particles released when an infected person coughs or sneezes.
It is this feature that made pneumonic plague particularly dangerous in times when antibiotics did not yet exist. Unlike other forms of the disease, it can spread relatively quickly within a family, medical institution or other closed community.
Bubonic plague is usually transmitted through the bites of infected fleas. Photo: John Montenieri/CDC/BSIP/picture alliance
How quickly the disease develops
The incubation period of pneumonic plague can be from one to several days. The first symptoms resemble a severe respiratory infection: high fever, chills, headache and fatigue. After that, the patient's condition can deteriorate very quickly. Chest pain, difficulty breathing, and a cough, sometimes with blood, appear. Without treatment, the disease can lead to death within a few days of the first symptoms.
That is why the World Health Organization (WHO) recommends that treatment be started immediately after the appearance of a suspicion of plague, without waiting for final laboratory confirmation.
The plague has not disappeared
Despite associations with the Middle Ages and the pandemic of the “Black Death”, the causative agent of the plague continues to circulate in nature. The bacterium Yersinia pestis persists in so-called natural foci among wild rodents and the fleas that parasitize them. It is practically impossible to completely eliminate such carriers of the infection, which is why the plague is still considered an endemic disease in a number of regions around the world. Most cases in humans in recent years have been registered in African countries, primarily in the Democratic Republic of the Congo and Madagascar. However, natural outbreaks of plague also exist in Asia, North and South America. According to WHO estimates, the bacterium is found on all continents, except Australia.
These outbreaks also include individual regions in Russia. They are particularly well studied in Siberia and Altai, where the circulation of the pathogen among some rodents has been observed for many decades. That is why one of the oldest scientific centers for combating plague in Russia operates in Irkutsk - the Irkutsk Institute for Combating Plague in Siberia and the Far East, which monitors natural outbreaks of particularly dangerous infections.
Such protective clothing against plague was used by doctors in Europe in the 17th century. Photo: Heinz-Dieter Falkenstein/imageBROKER/picture alliance
Specialists pay particular attention to the border areas between Russia and Mongolia. In August 2026, Russian and Mongolian scientists confirmed the activity of a large cross-border natural outbreak of plague on the border between the two countries. The pathogen was discovered during joint monitoring, after which the two countries agreed to continue regular monitoring of the situation at least until 2029. Mongolia is considered one of the countries where natural outbreaks of plague persist over a significant territory.
Can pneumonic plague be treated
Today, pneumonic plague is considered a treatable disease. The causative agent is sensitive to a number of widely used antibiotics, and timely treatment significantly reduces the risk of severe complications and death. Early diagnosis is key. If treatment is started in the first hours or days after the onset of symptoms, the chances of recovery remain high. In the event of a confirmed diagnosis, the patient is isolated, and people who have been in close contact with him may be prescribed a prophylactic course of antibiotics.
Modern specialists view pneumonic plague not so much as a deadly disease, but as a dangerous but controllable infection, requiring rapid detection and operational anti-epidemic measures.
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Source: www.dw.com