The first known outbreak of cyclosporiasis in the US occurred in 1990 in a Chicago hospital's physicians' dormitory and was attributed to an infected water source. In 1996-97, US epidemics of cyclosporiasis were attributed to infected Guatemalan raspberries, basil, and mesclun lettuce. The most recent outbreak resulted from exposure to contaminated berries at a social function in Ontario, Canada in 1999. Otherwise, only sporadic cases, primarily involving travelers, have been documented. Cyclospora species sporulate exogenously and have 2 sporocysts per oocyst.
Transmission follows ingestion of oocysts in fecally contaminated water or produce.
The median incubation period is 1 week, during which time the organism invades enterocytes of the small intestine. Disease manifests by protracted and relapsing gastroenteritis. Cyclospora species are characterized by an anterior polar complex that allows penetration into host cells, but the life cycle of the parasite and the mechanisms by which it interacts with human host target cells to cause disease are poorly understood. Cyclosporiasis is endemic in Haiti, Nepal, and Peru, with a strong seasonal predominance during rainy spring or summer months. Cases also have been reported in travelers returning from Mexico, Southeast Asia, Puerto Rico, Indonesia, Morocco, Pakistan, and India.