and sizes ranging from an Amoeba which can change its shape to Paramecium with its fixed shape and complex structure. They live in a wide variety of moist habitats including fresh water, marine environments and the soil. Protozoan infections are parasitic diseases caused by organisms formerly classified in the Kingdom Protozoa. They include organisms classified in Amoebozoa, Excavata, and Chromalveolata. Examples include Entamoeba histolytica, Plasmodium (some of which cause malaria), and Giardia