Bubonic Plague, aka Black Death, was transmitted from fleas. These fleas had previously attached themselves and infected the rats on ships traveling from China. Wherever the ships docked, the plague was spread. One-third of the population in Europe died during the 1300s.
It is not completely eradicated globally, but has not been an issue in Europe since the 1600s. The reason is unknown; could be some genetic protection, control of the rat population, etc.