Plague

ARTICLE SECTIONS

Introduction Signs and symptoms Causes Risk factors When to seek medical advice

Screening and diagnosis Complications Treatment Prevention

Introduction

Plague is a life-threatening infection caused by the organism Yersinia pestis, the bacterium that caused the 14th-century Black Death plague pandemic.

Plague-causing bacteria still exist in the environment today, although their effect has abated dramatically. The major threat of plague these days comes not through natural transmission, but through intentional transmission, perhaps by terrorists as an agent of biological warfare.

In nature, infected fleas transmit Y. pestis primarily among rodents. When a plague outbreak among rodents kills many of them in short order, infected fleas that were feeding on the rodents' blood jump to other animals and humans, spreading the infection.

During the Black Death, plague caused 20 million to 30 million deaths in Europe. More recent pandemics through the late 19th century killed millions of people worldwide. Improved living conditions and health services have made such large-scale outbreaks of natural plague unlikely, but occasional isolated plague cases continue.

These days, weapons may be more likely than rats to cause a plague pandemic. Plague bacteria could conceivably be put into a form that could be sprayed through the air, infecting anyone inhaling the bacteria and causing pneumonic plague. This form of plague affects your lungs and can spread from person to person. Fortunately, when given promptly, antibiotics can effectively treat plague most of the time.

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Signs and symptoms