Clinical Diagnosis

Health care providers should consider Cyclospora as a potential cause of prolonged diarrheal illness, particularly in patients with a history of recent travel to areas where the disease is endemic. Tests for Cyclospora are not routinely done in most laboratories, so health care providers need to specifically request testing for this parasitic infection.

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Laboratory Diagnosis

Cyclospora infection is diagnosed by examination of stool specimens. Diagnosis can be difficult because even persons experiencing symptoms may not "shed" enough oocysts in their stool to be readily detectable in laboratory tests. Therefore, patients may be asked to submit several stool samples over several days.

Microscopic methods for diagnosis involve looking for the parasite in stool under the microscope. Staining techniques, such as acid-fast staining, are often used to make Cyclospora oocysts more visible under the microscope. In addition, Cyclospora oocysts are autofluorescent, meaning that when stool containing oocysts is viewed under an ultraviolet (UV) microscope the oocysts fluoresce blue or green against a black background. Molecular diagnostic methods, such as the polymerase chain reaction (PCR), are used to look for the parasite’s DNA in the stool.

More on: Key points for the laboratory diagnosis of cyclosporiasis