Cyclospora species as a gastrointestinal pathogen in immunocompetent hosts

Previous reports of diarrhea resulting from Cyclospora species have been linked to travelers and immuno-compromised patients. We conducted a prospective study of 1,042 formalin-ethyl acetate fecal concentrates collected from patients with diarrhea. Between May and November 1993, we identified three patients for whom studies were positive for nonrefractile spherical organisms measuring 10 mm in diameter and containing a cluster of refractile membrane-bound globules. The cysts exhibited variable acid fastness consistent with Cyclospora species. These three patients had no history of recent travel and presented with relapsing, watery, nonbloody diarrhea that lasted from 12 days to 8 weeks. No other parasitic or bacterial pathogens were identified in their stools. All three instances of diarrhea occurred in May or June. No common source of food or water was identified. None of these patients were immunosuppressed, and their diarrhea resolved sponta-neously. We suggest that Cyclospora species should be considered in community-acquired diarrhea. Cyclospora cayetanensis is a newly recognized protozoal par-asite. It has been implicated as the etiologic agent of prolonged watery diarrhea, fatigue, and anorexia in humans. The mech-anism of transmission is presumed to be ingestion of contam-inated water (1). First reported in the diarrheal stools of trav-elers to Mexico and Haiti (13), these Cyclospora organisms have since been identified in patients in the United States