Lyme borreliosis is now acknowledged as the most highly prevalent arthropod-borne human disease in northern temperate regions of the world. The majority of the publications it has generated concern clinical aspects, and a book dealing with the complex biology and ecology of the causative organisms in a worldwide context is overdue. This book describes the basic characteristics of the disease, the biology of the pathogens in their vectors (ticks) and vertebrate hosts, their ecology in different regions of the world and the global epidemiology of the disease. The final chapters address the prevention and control measures that have resulted from this knowledge.