Cyclospora cayetanensis^[9] is a coccidian parasite of humans which may cause protracted watery diarrhoea and other intestinal disturbances, especially in AIDS patients. It, or similar organisms (sometimes referred to as CLBs-originally ‘cyanobacter- or ‘coccidia-like’ bodies, now ‘cyclospora-like’ bodies) have been reported from tropical and temperate zones of all continents. The parasites inhabit the intestinal enterocytes and undergo a life cycle similar to that of Cryptosporidium. The small spheroidal oocysts (8–10 μm in diameter) contain two sporocysts, each with two sporozoites. Transmission depends on ingestion of the oocysts, which are passed out in faeces. The sporozoites emerge in the intestine of the new host, and invade enterocytes. Diagnosis depends on detection of the oocysts in stool.