In this book, the authors present current research in the study of the biology, classification and role in disease of protozoa. Topics discussed include the current and prospective tools for the control of cattle-infecting Babesia parasites; biological rhythms and cell behaviour in paramecium; the use of protozoan tetrahymena as a cell model; anaerobic energy metabolism in protozoa; the biology of gregarines (protozoa: apicomplexa); the biology of parasitic protozoa cysts involved in human water-borne infections; and the effect of nickel toxicity to nutrient removal by selected indigenous protozoan species in waste-water systems.