Black Death
The Black Death may have begun in Central Asia or East Asia. It definitely appeared in Crimea in 1347. It was probably carried by fleas living on black rats, which traveled on Genoan ships and brought the plague to port cities around the Mediterranean. Rats may also have traveled along trade routes like the Silk Road and brought infected fleas to European cities. When the fleas bit humans, they infected them with the plague by injecting a bit of Y. pestis bacteria into the wound. Symptoms would start three to seven days later.