Intestinal protozoal diseases

Both pathogenic and nonpathogenic protozoans may inhabit the human intestines.
The most important pathogenic protozoans are Entamoeba histolytica, Giardia lamblia, Dientamoeba fragilis and Cryptosporidium parvum. 
Some pathogenic intestinal protozoans colonise the small intestine, others the large intestine. Protozoans are unicellular parasites that are able to move within the intestines with the aid of flagella, cilia or pseudopods.