Pneumonic plague? Its a bacteria that is carried by infected fleas on rats. The Black Death in the Middle Ages burned like a wildfire through European society. Almost three fourths of the population was dead before it had run its course. We haven't had a pandemic for the last century.
"Show me just what Mohammed brought that was new, and there you will find only things evil and inhuman, such as his command to spread by the sword the faith he preached." - Manuel II Palelogus