Studies on a newly emerging protozoal pathogen: Cyclospora cayetanensis.

Cyclospora is frequently misdiagnosed with Cryptosporidia. Stool samples were collected from 150 immunocompromised patients and concentrated by the parasep faecal parasite concentration and the discontinuous percoll gradients methods. Wet mount examination was done and the parasite was successfully stained with modified Ziehl Neelsen (ZN) and safranin methylene blue stain. Cyclospora was detected in 4% of cases examined. Cyclospora was easily differentiated from Cryptosporidia by using the modified detergent ZN stain whereby Cyclospora resist staining and Cryptosporidia pick up the pink colouration. Scanning and transmission electron microscopic examination were done to the unsporulated Cyclospora oocysts. They appeared as spherical objects with an outer fibrillar coat, an indentation and sutures. These spherical objects also contained light and dark granules. In studying the possible sources of transmission of this parasite, sporulated and unsporulated oocysts were detected in tap water and lettuce heads which support the theory that water and food could be the sources of transmission of this parasite.