The plague, the rare bacterial infection infamous for killing tens of millions of people in 14th-century Europe, has recently drawn attention and sparked concerns in Russia after a worker at a plague research institute in Siberia died of pneumonia.
While the concerns around plague stem from a perception that the deadly disease went away totally. It never did. However, today, it can be treated effectively with antibiotics.
Between 2019 and 2025, most human cases have been reported in Africa, particularly in Congo and Madagascar, according to the World Health Organisation.
Deep Dive
Does plague still exist, and how common is it today?
Can plague be treated with antibiotics?
Was plague confirmed as the cause of the Siberian lab worker’s death?
Plague is very rare, with 1,000 to 2,000 people diagnosed with plague every year worldwide, according to a clevelandclinic.org report.
In the US, there are an average of about seven human cases each year, per the the Centers for Disease Control and Prevention, with most cases reported in rural parts of the American West.
The death of the worker at Irkutsk Antiplague Research Institute in Siberia has raised alarm after unconfirmed media reports suggested she may have died of pneumonic plague. Russian authorities, however, said testing found no evidence of plague. The research institute has since been quarantined.
Reports of a second case of unknown pneumonia in irkutsk also surfaced, however, Russian health watchdog dismissed the same as incorrect, according to Russian news agency TASS.
{{/usCountry}}Reports of a second case of unknown pneumonia in irkutsk also surfaced, however, Russian health watchdog dismissed the same as incorrect, according to Russian news agency TASS.
{{/usCountry}}Moreover, no dangerous pathogenic microorganisms were detected after preventive measures were completed for all individuals who had contact with the employee of Irkutsk anti-plague institute, Reuters reported, citing independent Russian news agency IFX.
"People think the plague is gone, it was something that occurred 500 years ago. It's not. It's here amongst us," Associated Press news agency quoted as saying Simon Clarke of the University of Reading in the UK.
"Unless you get rid of those wild animals, which of course is not possible, then you're not going to get rid of the bacteria."
What is plague
Pneumonic plague and the better-known bubonic plague - also called the Black Death - are caused by the same bacterium, Yersinia pestis. The bacteria naturally circulate among rodents such as prairie dogs and rats. Fleas that feed on infected animals can then spread the bacteria to people through their bites.
Plague can attack lymph nodes, lungs and blood People in Siberia have been dying from plague for at least 5,500 years. The earliest evidence of a form of the disease was found in teeth from ancient hunter-gatherers living north of the region's Lake Baikal, according to the AP report.
Plague can be a very severe disease in people, with a case-fatality ratio of 30 per cent to 60 per cent for the bubonic type, and it is always fatal for the pneumonic and septicaemic kinds when left untreated, according to WHO.
What happens in bubonic plague
Bubonic plague is the most common form of the infection. It causes painfully swollen lymph nodes, most commonly in the groin, armpit and neck. These swollen nodes, known as buboes, are accompanied by symptoms such as sudden high fever and chills, headaches, and pain in the abdomen, legs and arms, according to the Cleveland Clinic.
There are two other forms of plague: Pneumonic plague, which can develop after inhaling the bacteria, affects the lungs; and septicemic plague, which infects the bloodstream. Both can be fatal if not treated early, according to the World Health Organization.
If left untreated, bubonic plague can develop into either of the other two forms.
Plague can spread through fleas or bodily fluids
Besides bites from infected fleas, people can contract plague through contact with infected bodily fluids. Health experts therefore recommend taking extra care when handling dead or sick animals.
Pneumonic plague can also spread through respiratory droplets from an infected person.
"If you cough, you can spread it to another person, but that doesn't travel very far," the report quoted as saying Dr Glenn Wortmann, MedStar Washington Hospital Center. "So you really need to be in face-to-face contact with that person to get pneumonic plague."
That's why "the chance of this spreading widely in Russia and then extending here to the US will not happen," he said.
Antibiotics can treat plague
The plague was never eradicated, but advances in prevention and treatment have made it far more manageable.
When diagnosed and treated early with antibiotics, plague can be cured. The key is to seek medical attention quickly, as the disease can otherwise become deadly.
A vaccine does exist, but the WHO recommends it only for people at high risk of infection, such as laboratory and healthcare workers. There is not strong evidence that vaccines can protect against the pneumonic form of the disease.
There is currently no plague vaccine available in the US.