Probably the deadliest pandemic in human history, the Great Plague, or Black Death, ravaged Europe from 1348-1350, killing up to half of the population in that short time. At its root was the bubonic plague-causing Yersinia pestis bacterium.
Originating in Asia, the plague first struck in China where it killed approximately 25 million people. It then spread into Europe following the Silk Road. Y pestis bacteria were carried by fleas, who themselves hitchhiked on the rats that thrived in the hulls of merchant ships.
After first landing on the shores of Italy in 1347, the Black Death had swept as far north as England by the following summer and continued onward to Germany and Scandinavia in 1348.
Highly infectious, the disease struck and killed its victims with startling speed. The telltale sign of infection was the appearance of swollen lymph
glands – called buboes – typically around the groin, neck and armpits. Sufferers then developed a high fever and began to vomit blood, usually dying within a week of the first symptoms showing. With no effective cure to keep it in check, the plague returned repeatedly for the next 300 years.