Bubonic plague is an infectious disease caused by Yersinia pestis bacteria. This disease has destroyed entire civilizations throughout history. Today, however, thanks to improved sanitation, better living conditions, and antibiotics, only a few thousand people contract the disease each year. The mortality rate is 50 to 90 percent if not treated; it drops to 15 percent when diagnosed and treated early.
Bubonic plague is an acute, infectious disease of humans, rodents, and ectoparasites (fleas, lice).
This disease is caused by bacteria called Yersinia pestis. These bubonic bacteria are found mainly in rodents, particularly rats, and in the fleas that feed on them. Other animals and humans usually contract the bacteria from rodent or flea bites.
(Click Plague and Animals for more information.)
Historically, bubonic plague has destroyed entire civilizations. In the 1300s, the "Black Death," as it was called, killed approximately one-third (20 to 30 million) of Europe's population. In the mid-1800s, plague killed 12 million people in China. Thanks to better living conditions, antibiotics, and improved sanitation, the disease is rare these days, occurring in a few thousand people worldwide each year.
Besides bubonic, there are two other forms of plague:
Depending on the circumstances, these other forms may or may not occur in combination with bubonic plague.
(Click Types of Plague for more information.)