Isospora belli Isospora belli Isospora belli is a coccidian parasite that infects the epithelial cells of the small intestine. Infection normally occurs in immunocompermised individuals, and outbreaks have been reported in institutionalized groups in the United States. Worldwide, in tropical and subtropical areas.
Trophozoites develop into schizonts that contain multiple merozoites.
Upon rupture of the schizonts, the merozoites are released, invade new epithelial cells, and continue the cycle of asexual multiplication. After a minimum of one week, the sexual stage begins with the development of male and female gametocytes. Fertiliztion takes place and Oocysts are formed. Oocysts are excreted in the stool. The oocyst contains one sporoblast.