Life cycle of Cyclospora cayetanensis
When freshly passed in stools, the oocysts of Cyclospora cayetanensis are not infective (1), so direct fecal-oral transmission cannot occur (this is in contrast to what is seen with another important coccidian parasite, Cryptosporidium). In the environment (2), sporulation occurs after days or weeks at temperatures between 22 C and 32 C, resulting in the division of the sporont into two sporocysts, each containing two elongate sporozoites (3). Fresh produce and water can serve as vehicles for transmission (4) and the sporulated oocysts are ingested (in contaminated food or water) (5). The oocysts excyst in the gastrointestinal tract, freeing the sporozoites, which invade the epithelial cells of the small intestine (6). Inside the cells, they undergo asexual multiplication and sexual development to mature into oocysts, which will be shed in stools (7). Potential mechanisms of contamination of food and water are still under investigation.
From Centers for Disease Control Parasites and Health website.