Book excerpt: New epidemics such as AIDS and "mad cow" disease have dramatized the need to explore the factors underlying rapid viral evolution and emerging viruses. This comprehensive volume is the first to describe this multifaceted new field. It places viral evolution and emergence in a historical context, describes the interaction of viruses with hosts, and details the advances in molecular biology and epidemiology that have provided the tools necessary to track developing viral epidemics and to detect new viruses far more successfully than could be done in the recent past. This unique book also lucidly details case histories and offers practical suggestions for the prevention of future epidemics. The contributors are leading authorities in their disciplines, and were selected both for their expert knowledge and for their ability to define and elucidate the fundamental issues. The book is highly accessible and has been written for a wide audience that includes virologists, public health authorities, medical anthropologists, evolutionary biologists, geneticists, infectious disease specialists, and social scientists interested in medical and health issues.