A young laboratory worker has reportedly died of pneumonic plague in the Russian province of Siberia, with around 200 people placed under quarantine.

It is a case that has put one of the world’s most feared diseases back in the headlines.

Here is what happened, what pneumonic plague actually is, and whether we should be worried.

What happened in Siberia

Darya Shipilova, a 28-year-old lab technician, is reported to have died in the Irkutsk region of eastern Russia after contracting the illness.

According to regional media, she worked at the Irkutsk Anti-Plague Institute and may have been infected when she broke a test tube containing the plague bacteria.

She was admitted to hospital in the town of Shelekhov in late September and died two days later, having been placed on a ventilator.

As many as 200 people who she may have come into contact with have since been placed under medical observation, and the local hospital has been quarantined.

Russia’s most senior public health official travelled to the region to take charge of the response, and a mask order was introduced in Irkutsk.

What is pneumonic plague?

Plague is an infectious disease caused by a bacterium called Yersinia pestis. It is the same bug behind the Black Death, which wiped out tens of millions of people across medieval Europe in the 1300s.

There are a few forms of the disease. The most common, bubonic plague, is usually spread by flea bites and causes painful swollen glands. Pneumonic plague is the rarest but most dangerous form.

It attacks the lungs and, crucially, can spread directly from person to person through airborne droplets when someone coughs.

Why it is so feared

Pneumonic plague moves fast. Symptoms can appear within a day or two, and without prompt treatment it is very often fatal.

That combination of speed, severity and the fact that it can spread through the air is what makes it so dangerous, and why authorities respond to even a single suspected case so aggressively.

Should you be worried?

For all its fearsome reputation, there is important context. Plague is treatable with common antibiotics if caught early, and modern public health systems are built to contain it quickly, which is exactly what is happening in Siberia.

It has not disappeared, with the World Health Organisation recording cases in around 10 countries in recent years, but outbreaks remain rare and localised.

The risk to people in Ireland and the wider world from this incident is considered negligible at present.

It is also worth noting that, although reports of this incident are widespread, there has been no formal confirmation of the case from Russia’s health ministry.