Infectious Agent

Cyclospora cayetanensis , a coccidian protozoan parasite.


Ingestion of infective Cyclospora oocysts, such as in contaminated food or water.


Most common in tropical and subtropical regions, where outbreaks are frequently seasonal (such as during summers and rainy season in Nepal); even short-term travelers can become infected. Outbreaks in the United States and Canada have been linked to imported fresh produce.

Clinical Presentation

Incubation period averages 1 week (range, 2 days to ≥2 weeks). Onset of symptoms is often abrupt but can be gradual; some people have an influenzalike prodrome. The most common symptom is watery diarrhea, which can be profuse. Other symptoms can include anorexia, weight loss, abdominal cramps, bloating, nausea, body aches, vomiting, and low-grade fever. If untreated, the illness can last for several weeks or months, with a remitting-relapsing course.


Diagnosed by detecting Cyclospora oocysts or DNA in stool specimens. Stool examinations for ova and parasites usually do not include methods for detecting Cyclospora unless testing for this parasite is specifically requested. Diagnostic assistance for Cyclospora and other parasitic diseases is also available from CDC (; 404-718-4745; Cyclosporiasis is a nationally notifiable disease.


Trimethoprim-sulfamethoxazole; no highly effective alternatives have been identified.


Food and water precautions (see Chapter 2, Food & Water Precautions); disinfection with chlorine or iodine is unlikely to be effective.

CDC website:


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Barbara L. Herwaldt