This book is the first major synthesis of theory and empirical knowledge regarding the ecology and epidemiology of infectious diseases in natural, unmanaged, animal and plant populations. Throughout the book, the contributors develop a dialogue between the patterns observed in empirical studies of disease in natural populations and the mathematical models used to dissect and examine the observed epidemiological patterns. The book is divided into a number of reviews and group reports by experts in various fields. Two sections synthesize important issues relating to the dynamics of microparasites and macroparasites, while the others discuss spatial patterns in disease dynamics and the evolutionary biology of parasites, pathogens and their hosts. This book will be of use to graduate students and specialists in mathematical biology and epidemiology.