“Remarkable achievements have been accomplished in the control of many epidemic infectious diseases in this century.”

—American Medical Association’s Council on Scientific Affairs

“AIDS does not stand alone; it may well be just the first of the modern, large-scale epidemics of infectious disease.”

—Laurie Garrett

Epidemics have been a major and recurring part of human history. Bubonic plague, caused by the bacterium Yersinia pestis, killed three quarters of Europe’s population in the fourteenth century. Epidemics of such diseases as smallpox, yellow fever, and tuberculosis routinely swept through U.S. cities prior to the twentieth century. As recently as 1919, a fatal form of influenza spread through much of the world, killing as many as 20 million people worldwide, including a half-million Americans.

During the twentieth century, however, the advent of modern medicine—including the development of the disciplines of...