The Coccidia are a group of organisms which parasitise the epithelial cells of the intestinal tract.

 This group includes Cryptosporidium parvum, Cyclospora cayetanensis and Isospora belli.

Microscopic Characteristscs	Cryptosporidium parvum	Isospora belli	Cyclospora cayetanensis
Size	4 - 6	20-33 - 10 - 19	8 - 10
Identified in formol-ether concentrate by light microscopy	No	Yes	Yes
Identified by modified Ziehl-Neelsen	Yes	Yes	Yes
Identified by Phenol Auramine stain	Yes	Variable	No