Plague!

Being sick is horrible. But it used to be worse. Inside this book, you'll see evidence of the plagues of the past--rotting skin, dissolving lungs, and sinister swelling all over the body. Diseases like the Black Death wiped out whole towns and villages. Tuberculosis consumed young people like a bloodsucking vampire. And Smallpox left its victims scarred for life--if they survived. At the time, no one knew where these killer diseases came from or how to treat them. But eventually doctors discovered how these diseases and others were spread. Being sick isn't quite as sickening as it was in the past