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[Cyclospora cayetanensis]

Cyclospora cayetanensis oocysts are spherical, 7.5-10 µm in diameter and unsporulated when passed in feces.  Sporulation in the environment is temperature-dependent and may take one to several weeks for an infective oocyst to contain two sporocysts, each containing two sporozoites.  Oocysts of C. cayetanensis will autofluoresce under ultraviolet (UV) microscopy.

A:  Oocysts of C. cayetanensis stained with modified acid-fast stain.  Note the variability of staining in the four oocysts.
B:  Two oocysts of C. cayetanensis stained with modified acid-fast stain.  Both oocysts failed to take up the carbol fuschin stain.  Image courtesy of the Arizona State Public Health Laboratory.

C:  Oocysts of C. cayetanensis stained with modified acid-fast stain.  Note the wrinkled edge and the lack of stain in the two oocysts.  Image courtesy of the Arizona State Public Health Laboratory.
D:  Oocyst of C. cayetanensis stained with modified acid-fast stain.

E, F:  Oocysts of C. cayetanensis stained with modified acid-fast stain.