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Cyclospora Cayetanensis

Cyclosporiasis is an intestinal illness caused by the unicellular, coccidian parasiteCyclospora cayetanensis. Transmission occurs by ingestion of fecally contaminated food or water. Cyclospora oocysts are not killed by routine chemical disinfection or sanitizing methods. Humans are the only known hosts of this parasite.

Cyclosporiasis is most common in tropical and subtropical regions of the world such as Mexico, the Caribbean and Central America. In the United States, cases of cyclosporiasis have been reported among travelers to such areas. Cyclosporiasis became a nationally notifiable disease in January 1999 after several large multistate outbreaks. Foodborne outbreaks occur in the United States almost every year in the spring and summer. Imported fresh produce such as basil, cilantro, lettuce, raspberries, snow peas and prepackaged salad mix are often implicated.

Cyclospora infection can be asymptomatic or symptomatic. Asymptomatic infection is most common in endemic regions. Among persons who develop symptomatic Cyclosporainfection, the incubation period averages 1 week (range: 2 to >14 days). Symptoms include watery diarrhea, loss of appetite, weight loss, abdominal cramping, bloating, nausea, fatigue, vomiting, and low-grade fever. The recommended treatment for cyclosporiasis is trimethoprim-sulfamethoxazole. Untreated individuals may have remitting and relapsing symptoms for 10 to 12 weeks.

Routine ova and parasite examinations of stool typically do not detect Cyclospora oocysts. They are detected with a modified acid-fast stain or a modified safranin stain. The latter stain has better sensitivity. Oocysts appear clear to pink and refractile. If the ova and parasite exam fails to detect oocysyts and Cyclospora infection is strongly suspected, molecular testing can be performed. The FilmArray Gastrointestinal Pathogen Panel utilizes nucleic acid amplification to detect multiple viral, bacterial and parasitic pathogens including Cyclospora.

Stool specimen is required for testing. Reference value is negative.


Casillas SM, Hall RL, Herwaldt BL. Cyclosporiasis Surveillance — United States, 2011–2015. MMWR Surveill Summ 2019;68(No. SS-3):1–16.

Visvesvara GS et al: Uniform staining of Cyclospora oocysts in fecal smears by a modified safranin technique with microwave heating. J Clin Microbiol 1997;35:730-733.

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