Plague is a disease that is caused by the bacterium, Yersinia
pestis. Humans usually get plague after being bitten by a rodent
flea that is carrying the plague bacterium or by handling an
animal infected with plague. Plague is infamous for killing
millions of people in Europe during the Middle Ages.
Today, modern antibiotics are effective in treating plague.
Without prompt treatment, the disease can cause serious illness
or death.
