Coccidians

Cyclospora cayetanensis and Cryptosporidium parvum. Oocysts in fecal smear (acid-fast stain, oil immersion). In a mixed infection of these two organisms from a patient with AIDS, the smaller oocysts of Cryptosporidium, (4-6 µm) take their typical pink-red stain and demonstrate the black granules that are usually present; in the center of the field, a larger (8-10 µm) pink-staining oocyst of Cyclospora without black granules is present.