Pneumonic plague: What is it and how dangerous can it be?

(NewsNation) — A Russian scientist has died and 200 people are under medical observation as the White House is monitoring a suspected pneumonic plague outbreak.

Russia has not confirmed that the worker died of pneumonic plague, with the death being attributed to pneumonia of unknown origin, but the case has prompted calls for more transparency from Moscow.

What is pneumonic plague?

Pneumonic plague is a disease caused when the bacterium Yersinia pestis, which causes the plague, enters the lungs.

It is the only form of the plague that can spread person to person through bacteria-containing droplets in the air.

It can also be caused when someone has bubonic or septicemic plague, caused by flea bites or contact with bacteria-containing bodily fluid or tissue, and the infection spreads to the lungs.

What are the symptoms of pneumonic plague?

The symptoms........

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