Cyclosporiasis: a new cause of diarrhea.

Cyclospora cayetanensis, a coccidian parasite, is a new cause of prolonged diarrhea. It has been most recently associated with ingestion of contaminated fruit. Although infection with C. cayetanensis is considered rare, the exact prevalence in Canada is unknown. Transmission is thought to occur through contaminated food and water. The incubation period varies from days to weeks. Patients present with nausea, vomiting, anorexia, bloating, abdominal cramping, increased gas and watery diarrhea. The illness may last up to 6 weeks and may respond to treatment with trimethoprim-sulfamethoxazole. C. cayetanensis is differentiated from other coccidians by its sporulation characteristics and its autofluorescence. To obtain a positive result of a laboratory test for the organism, a modified Ziehl-Neelsen acid-fast stain is recommended. Proper laboratory handling of specimens is facilitated by inclusion of clinical information on requisition forms.