The present book evaluates in chapters contributed by renowned researchers the latest findings on, landmarks in the discovery of blastocystis, epidemiology, transmission and zoonotic potential, morphology of human and animal blastocystis isolates, clinical aspects of blastocystis infections, behavioral decision analysis : what makes us sick?, blastocystis-host interactions, molecular approaches on the systematical position, genetic polymorphism, blastocystis from a statistical point of view, diarrheas due to different agents of disease, zoonotic diseases in comparison.