This photomicrograph of a fresh stool sample, which had been prepared using a 10% formalin solution, and stained with safranin, revealed the presence of three uniformly stained Cyclospora cayetanensis oocysts in the field of view.Created:
This photomicrograph of a fresh stool sample, which had been prepared using a 10% formalin solution, and stained with modified acid-fast stain, revealed the presence of four Cyclospora cayetanensis oocysts in the field of view. Compared to wet mount preparations, the oocysts are less perfectly round and have a wrinkled appearance due to this method of fixation. Most importantly, the staining is variable among the four oocysts.Created:
Centers for Disease Control/Division of Parasitic Diseases and Malaria
EOL staff
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.