Parasitology is the study of parasites, their hosts, and the relationship between them. Many molecular tools have been developed over the past decades to determine genotypes and subgenotypes of parasites. This book describes the use of DNA technology in epidemiological investigations for parasitic research. During recent years, a striking number of studies also provided new insight into the cellular interactions and molecular mechanisms of malaria parasites during liver infection. This book summarises novel findings on the malaria liver stage biology. Furthermore, organ transplants have become more frequent world-wide. Unfortunately, parasitic infections can be transmissible by transplantation. The authors of this book describe the most useful methodology, as well as its application for the precise diagnosis of the parasite in the laboratory. The transmission mechanisms and the main factors of risk of each one of the parasites involved is discussed as well. Other chapters in this book examine the toxoplasma gondii, an intracellular protozoan parasite which infects potentially any warm-blooded animal, and the giardia duodenalis trophozoites, which have a remarkable ability to attach to the surface of epithelial cells of infected hosts. The various approaches that have been used to identify, isolate and characterise novel genes from the parasite genome of Babesia gibsoni are examined as well.