Cyclosporiasis Workup

Updated: Nov 10, 2022
  • Author: Shipra Gupta, MD; Chief Editor: Russell W Steele, MD  more...
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Laboratory Studies

Diagnosis is based on the microscopic detection of oocysts in fecal specimens. Stool testing for ova and parasites does not typically include testing for Cyclospora. Microscopic examination of fecal specimens with acid-fast staining are indicated in cyclosporiasis.

Oocysts of C cayetanensis stained with modified ac Oocysts of C cayetanensis stained with modified acid-fast stain. Note the variability of staining in the four oocysts. Courtesy of the CDC (

Stain Cyclospora species using modified Ziehl-Neelsen or Kinyoun acid-fast stains. These species are not visualized by Gram, Giemsa, silver, or hematoxylin-eosin staining.

Oocysts are round and resemble those of Cryptosporidium, but they are twice the size (8-10 µm). A modified safranin staining protocol provides consistent reddish-orange staining of oocysts and can simplify identification of the oocysts. [29]

Cyclospora spp oocysts are autofluorescent blue fluorescence is seen with UV light (330-365nm filter) and blue-green fluorescence can be seen with blue excitation (450-490nm filter). [30]

Oocyst of C cayetanensis viewed under UV microscop Oocyst of C cayetanensis viewed under UV microscopy. Courtesy of the CDC (

This property is not specific for Cyclospora species, however, and wanes as the specimen ages.

Examination of multiple stool samples, collected at different times is recommended as even symptomatic patients may not shed enough oocysts for detection.

No serologic assays are currently available to detect antibodies to Cyclospora species.

Polymerase chain reaction (PCR) tests for detection of Cyclospora DNA in stool specimens are available mainly for outbreak investigations; however, they are not currently approved by FDA. [30]



Small-bowel biopsy reveals pathologic changes, however, they are non-specific. These include blunting and atrophy of villi with acute and chronic inflammation, and hyperplasia of crypts.