Plague

Plague is an infection caused by the bacterium Yersinia pestis. The bacteria are found mainly in rats and in the fleas that feed on them. People and other animals can get plague from rat or flea bites. Historically, plague destroyed entire civilizations. In the 1300s, the "Black Death," as it was called, killed approximately one-third of Europe's population. Today plague is uncommon. This is largely due to better living conditions and antibiotics.

There are three forms of plague:

• Bubonic, which causes the tonsils, adenoids, spleen and thymus to become inflamed. Symptoms include fever, aches, chills and tender lymph glands
• Septicemic, in which bacteria multiply in the blood. It causes fever, chills, shock and bleeding under the skin or other organs
• Pneumonic, in which the bacteria enter the lungs and cause pneumonia. People with the infection can spread this form to others. This type could be a bioterror agent

Treatment for plague is a strong antibiotic. There is no vaccine for plague.

NIH: National Institute of Allergy and Infectious Diseases