The Black Death
The cause of the Black Plauge was do to the fact of "Fleas on Rats" that stowed away on trade and cargo ships. That way it was eaiser for the diease to spread across Europe around 1346-1352. There were 3 main waring signs/symptoms which includes pneumonic which attack the lungs, septicemic which appeared in the bloodstream, and finally bubonic casued buboes on the body. It killed 1/3 of the population, its still considerd the worst pandemic in the world.