Coccidia and Other Protozoa

Abstract

The subjects of this chapter are a diverse group of obligate intracellular parasites from three taxonomic families in the phylum Apicomplexa. The family Eimeriidae includes several genera of organisms usually considered as “coccidia”. Most species have only one host in the life cycle, and most develop within epithelial cells of the intestine or kidney. The family Cryptosporidiidae contains one genus, Cryptosporidium, which are small coccidial organisms that parasitize the microvillus border of epithelial cells in a variety of sites. The family Sarcocystidae contains several genera of organisms with a life cycle in which sexual stages and oocyst formation occurs in the intestine of one host (usually a carnivore) and asexual stages occur in other tissues of another host. Waterfowl are infected with asexual stages of at least two genera, Sarcocystis and Toxoplasma, from this family.