Filarial nematodes constitute an important group of human pathogens in tropical regions of the world. Diseases associated with these worms are generally separated into two categories: filariasis, caused by infections of lymphatic dwelling parasites and onchocerciasis, or river blindness, caused by infections of Onchocerca volvulus. Other filariae specifically infect humans and it is likely that zoonotic filarial infections may alter the outcome of infections with human parasites. The chapters in this book cover concepts that, in most instances, overlap all of these parasites as well as focus on emerging ideas. "The Filaria", volume five of "World Class Parasites", has been written for researchers, students and scholars. It is intended to supplement more formal texts that cover taxonomy, life cycles, morphology, vector distribution, symptoms and treatment. It integrates vector, pathogen and host biology and celebrates the diversity of approach that comprises modern parasitological research.