Plague Home > About the Plague
Plague is an infectious disease that is caused by bacteria called Yersinia pestis. These bacteria are found mainly in rodents, particularly rats, and in the fleas that feed on them. Transmission to humans usually occurs through rodent or flea bites. Fortunately, due to improved living conditions, medications, and other factors, plague is now considered a rare disease.
There are three forms of plague:
- Bubonic (the most common type, where bacteria infect the lymph system)
- Septicemic (where plague bacteria multiply in the blood)
- Pneumonic (the most serious type, where plague bacteria infect the lungs and cause pneumonia).
These different types can occur separately or in combination. Antibiotics are the typical choice of treatment. In cases where treatment is not provided, the mortality rate is 50 to 90 percent. If treated early, the rate drops to 15 percent.
(Click Plague to learn more about this disease. This article tells you what you need to know about the disease's incubation period, medical conditions with similar symptoms, and more.)