Parasitology, the study of parasites and their relationships to their hosts, is one of the most fascinating areas of the biology. Parasitology has traditionally been limited to parasitic Protozoa, Platyhelminthes, and Nemathelminthes, as well as those species of organisms that serve as vectors for parasites. But now a day it is approaching to all groups of Parasites including unicellular to multicellular organisms with special reference to taxonomy, classical morphology, ultra topography, bioecology, epidemiology, molecular heterogeneity, phylogeny, biochemistry, and in silico genome analysis to resolves it ambiguity in identification to biodiversity, biotechnology, and clinical diagnosis and health consequences. "Parasitology: Risks and Challenges for Health and Sustainability" emphasizes how parasites influence, and are influenced by, a complex web of interacting factors. The book has been divided into eight conventional chapters that cover all the aspects of Parasitology to show how topics are inter-related. The reader will find certain subjects are picked up, put down, discussed in more detail elsewhere, and then returned to in a later chapter.