Cyclosporiasis is a disease caused by infection with Cyclospora cayetanensis, a pathogenic apicomplexan protozoan transmitted by feces or feces-contaminated food and water.^[1] Outbreaks have been reported due to contaminated fruits and vegetables. Because the oocysts of Cyclospora must sporulate in the environment for 1–2 weeks before they become infectious, direct person to person transmission is very unlikely,^[2] but it can be a hazard for travelers as a cause of diarrhea.

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Cause

Cyclosporiasis primarily affects humans and other primates. When an oocyst of Cyclospora cayetanensis enters the small intestine, it invades the mucosa, where it incubates for about one week. After incubation, the infected person begins to experience severe watery diarrhea, bloating, fever, stomach cramps, and muscle aches.^[1]^

The parasite particularly affects the jejunum of the small intestine. Of nine patients in Nepal who were diagnosed with cyclosporiasis, all had inflammation of the lamina propria along with an increase of plasma in the lamina propria. Oocysts were also observed in duodenal aspirates.^[3]

Oocysts are often present in the environment as a result of using contaminated water or human feces as fertilizer.