Plague (Yersinia pestis)
Infectious agent: Yersinia pestis
Description of illness: Plague is a disease that affects humans and other mammals, caused by the bacterium, Yersinia pestis. Humans usually contract plague after being bitten by a rodent flea that is carrying the plague bacterium or by handling an animal infected with plague. Antibiotics are effective in treating plague; however without prompt treatment, the disease can cause serious illness or death.