Bubonic Plague (also known as the Black Death) was a nasty disease that repeatedly swept through Medieval and Renaissance Europe. Rats and other rodents carried fleas infected with a deadly bacteria—deadly to people, anyway. Sick humans then passed it to other unlucky folks by coughing or sneezing on them. It took only a few hours or days to get sick and many died. The Black Death got its name because it turns the skin of its victims black. Poor Pietro Perugino!