The Black Death reached Europe in the late 1340, killing nearly 25 million people. It lingered on for centuries, especially in cities. The cause of this plague wasn't discovered until the most recent global outbreak, which started in China in 1855 and oficially ended in 1959. In China, specialists noticed that rats showed very similar plague symptoms to people, and that human victims often had fleabites. This disease is often transmitted by the rat flea.
