Even in areas of the world that still experience outbreaks, mortality rates from plague are estimated to be eight to 10 percent. The disease that caused the most lethal epidemics recorded in history and killed 60 percent of the people in medieval London and Florence is no longer on the most feared-killers list.
"O happy posterity, who will not experience such abysmal woe and will look upon our testimony as a fable," wrote Renaissance poet Petrarch, who lost his beloved and muse, Laura, to the "Black Death." Petrarch, a native of the Republic of Florence, witnessed a terror we can only find in end-of-the-world Hollywood blockbusters today: The lucky few who had escaped the Black Death spent most of their time carrying dead bodies and burying them by the thousands in pits around churches and elsewhere in the cities. The corpses lay on top of each other, separated by thin layers of clay, "just as one makes lasagna with layers of pasta and cheese," in the words of a 14th-century Florentine chronicler whom historian Ole J. Benedictow cites in his studies on the impact of Black Death.
Researchers have identified three types of plague, characterized by different symptoms and means of transmission. The bubonic plague, which is assumed to have been the chief killer in medieval outbreaks, causes painful, swollen lymph nodes (called buboes) around the groin, armpit, or neck. Septicemic plague spreads in the blood stream and comes from flea bites or contact with plague-infected body tissues. The pneumonic (or pulmonary) plague is an advanced stage of bubonic plague when the disease is passed directly, person to person, through airborne droplets coughed from the lungs.