The Bubonic Plague
The bubonic plague is an infectious disease caused by bacteria that affects humans and some animals (mostly rats and prairie dogs). While historically, the disease has killed millions of people worldwide, there are currently only 1,000 to 3,000 cases per year. The mortality rate is 50 to 90 percent if plague is left untreated; it drops to 15 percent with early diagnosis and treatment with antibiotics.
The bubonic plague is an acute, infectious disease present in rodents, humans, and ectoparasites (fleas, lice).
Historically, the 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. The plague killed 12 million people in the mid-1800s 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.
The bubonic plague is caused by bacteria called Yersinia pestis. These plague bacteria are found mainly in rodents, particularly rats, and in the fleas that feed on them. Humans can also acquire the disease from rodent or flea bites.