For health professionals: Cyclosporiasis (Cyclospora)

Find detailed information on cyclosporiasis for health professionals.

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What health professionals need to know about cyclosporiasis

Cyclospora oocysts, when freshly passed in the stool, are not sporulated. Therefore, they are not infective. Oocysts require 7 to 15 days outside the host to develop and mature into the infective sporulated oocyst. Thus, direct fecal-oral transmission is precluded.

When ingested, Cyclospora oocysts excyst in the gut and release sporozoites, which invade the epithelial cells of the small intestine.

Clinical manifestations

After an average incubation period of 1 week, symptomatic infections typically manifest as watery diarrhea, which can be severe.

Other symptoms include:

  • fatigue
  • anorexia
  • myalgias
  • weight loss
  • abdominal pain
  • low-grade fever
  • nausea and vomiting

Untreated infections typically last for 6 to 7 weeks and may follow a relapsing course. Infections, especially in disease-endemic settings, can be asymptomatic.


Cyclosporiasis can be diagnosed by identification of the Cyclospora oocyst in:

  • duodenal aspirates
  • small bowel biopsies
  • fresh or iodine-preserved stool

When testing stool specimens, diagnosis can be difficult. Even persons who are symptomatic might not shed enough oocysts in their stool to be readily detectable by laboratory examinations. Therefore, patients might need to provide several specimens collected on different days.

With acid-fast or safranin O staining, oocysts can be seen as 10 µm spheres with clusters of refractile globules. Diagnosis can be performed using modified Ziehl-Neelsen (MZN) and auramine-rhodamine stains.


Trimethoprim-sulfamethoxazole (TMP-SMX) is the first-line treatment for cyclosporiasis, with symptom resolution usually noted 2 to 3 days into therapy.

No highly effective alternative antibiotic regimen has been identified yet for patients who:

  • have a sulfa allergy
  • do not respond to the standard treatment


Health professionals in Canada play a critical role in identifying and reporting cases of cyclosporiasis. See the surveillance of cyclosporiasis section for more information on surveillance in Canada.

Consult the national case definition for additional information. 

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