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.
Mortality is exceptionally rare.
Very little morbidity results from this infection, except in persons with underlying immunosuppression, in whom chronic diarrhea can develop. No racial predilection exists. Diarrhea is the hallmark of infection. Onset is abrupt, 1-14 days after exposure to a contaminated source. The diarrhea is described as profuse, malodorous, and watery and can cause dehydration and weight loss.