The Black Death
In the 14th century, European traders brought home more than they anticipated upon their return with the riches of the East. Originating in China and spreading quickly along the Silk Road, the Black Death—aptly named for the black, necrotic pustules that grew on the skin—ravaged both Europe and Asia for nearly four years, carried by rats playing host to fleas infected with the bacterium Yersinia pestis. Population density and the unsanitary conditions of city living ensured that virtually no one was safe from contracting the plague. By the time it subsided, about 75 to 200 million individuals succumbed to the illness, impacting Europe and Asia’s economies in addition to influencing the consideration of better hygienic practices.