Although the earliest accounts of diphtheria date back at least 2,000 years, this disease was first associated with major epidemics in Europe during the 16th century. By the 18th century, diphtheria became a major cause of childhood illness and death in the New World. With the advent of widespread vaccination in the 1920s, the number of cases and deaths dropped dramatically. However, in areas where vaccination rates drop, diphtheria can rapidly become reestablished, as seen in the late 1990s in several former Soviet republics. Diphtheria is a bacterial infection caused by Corynebacterium diphtheriae, which attacks the respiratory system. Diphtheria describes the disease, the bacteria that causes it, and the development of effective treatments. Chapters of this title include: History of Diphtheria; How Does Corynebacterium Diphtheriae Cause Disease; How Is Diphtheria Treated; How Is Diphtheria Prevented; Resurgence of Diphtheria in the Former Soviet Union; and, Uses of Diphtheria Toxin.