Diseases have a history, and understanding that history helps us understand how best to treat and control disease today. Today's students are confronted with a panoply of often-frightening illnesses and afflictions - the series provides students with the information that they need to understand the origin of various maladies, how they impact contemporary society, and how doctors and researchers from around the world are fighting to devise treatments to alleviate or cure these diseases. This volume, , covers a common affliction that comes in many different forms, which can be fatal or leave the patient disabled, and which strikes a surprising number of younger people.