Cyclospora
Cyclospora species are found in humans, insectivores and other animals; however Cyclospora cayetanensis is the only species of this genus found to infect humans.
The oocyst of Cyclospora cayetanensis are spherical in shape and are up to twice the size of Cryptosporidium oocyst, at 7.5 – 10um in diameter. The oocyst is surrounded by a 50nm thick wall and outer fibrillar (63nm) coat that contains complex carbohydrates and lipids which make the oocyst acid fast. Within the oocyst are two long oblong sporocyst that in turn contain two infectious sporozoites. Once ingested by the host, the oocyst excyst in the gastrointestinal tract freeing the sporozoites which then invade the epithelial cells of the small intestine. Inside these cells, the sporozoites undergo asexual multiplication and sexual development to form unsporulated non-infectious oocysts that rupture the host cell and are then excreted with the stool. In the environment, after 7 to 12 days and with temperatures between 22 and 32oC, sporulation occurs which results in division of the sporont into two sporocysts.
