Insect-transmitted rickettsiales diseases are significant sources of morbidity and mortality all over the world. Their incidence has been increasing in recent years in large part due to climate change and the movement of animals carrying the insect vectors. Currently there are no effective vaccines against diseases caused by members of the order Rickettsiales. Rickettsiales diseases are often misdiagnosed; this book is intended to serve as a tool for their understanding and diagnosis. Rickettsiales covers the seven main genera: Anaplasma, Ehrlichia, Midichloria, Neorickettsia, Orientia, Rickettsia and Wolbachia. Discussion of each genus includes immunology and molecular biology of host-pathogen interactions, epidemiology and diagnosis, and vaccination strategies and therapies.