This book describes the major discoveries regarding chlamydial evolution, virulence, and pathogenesis as they relate to human chlamydial diseases worldwide. It discusses these discoveries through the application of new and advanced bioinformatics and statistical tools for comparative genomics, microarray analyses, and functional genomics. This monograph also deals with the threat posed by the expanding and evolving repertoire of chlamydial organisms that originate from reptiles and lower-vertebrate mammals, as well as from the environment. It includes an in-depth discussion on how these research discoveries help to bring about approaches for global disease interventions including vaccine development, and on the broader public health impact. This book will appeal to those interested in infectious diseases generally.