Plague is a bacterial zoonotic disease (a disease we get from animals), caused by the bacterium Yersinia pestis. It can result in three forms of disease: bubonic plague, pneumonic plague and septicemic plague. Over the centuries, plague has killed over 200 million people, but today, outbreaks from plague are rare.
Plague still occurs in parts of Africa, southeastern Europe, Asia and the Americas. In the US, 10 to 15 cases occur each year, in the Southwest. In 2007, over 2,000 cases were reported worldwide, with over 99 per cent of these occurring in Africa, and about half of these in the Democratic Republic of Congo.