Protozoology is the branch of zoology which deals with protozoans. Medical parasitology is the branch of medicine which also deals with disease-causing parasitic protozoans, how they infect humans, mechanisms of disease, and how to control or avoid them. Diseases of humans that are caused by protozoa namely malaria, sleeping sickness, Chagas disease, amoebic dysentery, coccidiosis, leishmaniasis and toxoplasmosis.
Protozoa are unicellular, heterotrophic eukaryotes that act important components of ecosystems. In addition, protozoa are important in a number of fields of medicine. In general, parasitic protozoans of major medical importance include certain species of amoebae, flagellates, and sporozoans. These groups exhibit a wide variety of morphologies. There is no one shape or morphology which would include a majority of the protozoa. Shapes range from the amorphous and ever-changing forms of ameba to relatively rigid forms dictated in part by highly ordered cytoskeletons or secreted walls or shells. Many protozoan species exhibit complex life cycles with multiple stages. Sometimes the different life cycle stages are so dissimilar that they have been mistaken for completely different species. These interesting protozoan characteristics are what attract researchers to conduct studies on this group of organisms.
Picture: http://stgmu.ru/userfiles/depts/biology_ecology/metodichki_i_uchebnye_posobiya/angl.yazyk/MEDICINSKAYa_PROTOZOOLOGIYa_angl.yaz..pdf
