Key facts
- Type: a microscopic single-celled protozoan (coccidian) parasite.
- Target: the lining of the small intestine.
- Not contagious person-to-person: oocysts need ~1–2 weeks outside the body to mature.
- Origin: endemic in tropical/subtropical regions; arrives via imported produce & travel.
Cyclospora cayetanensis is a microscopic, single-celled protozoan parasite — a coccidian — that infects the small intestine and causes the illness cyclosporiasis. It is not a bacterium and not a virus, which is why it is not affected by ordinary antibacterial or antiviral measures and needs a specific antiparasitic treatment approach.
The lifecycle — and why it’s not contagious
People infected with Cyclospora pass oocysts in their feces. Crucially, those oocysts are not immediately infectious: they need roughly one to two weeks in the environment (given warmth and moisture) to “sporulate” and become capable of causing infection. That single fact explains why Cyclospora does not spread directly from person to person — unlike norovirus — and why it is instead a food- and water-borne infection. Someone becomes infected by swallowing sporulated oocysts, typically on fresh produce that was exposed to contaminated water.
Where Cyclospora comes from
The parasite is endemic in tropical and subtropical regions — including parts of Peru, Cuba, Mexico, Guatemala, Nepal, India, Southeast Asia and the Dominican Republic. In North America it appears largely through imported fresh produce and among travelers returning from those regions. See how you’re exposed through produce.
How it compares to other gut bugs
“Parasite,” “bacteria” and “virus” are often used loosely, but they behave differently. Compare Cyclospora with Giardia, Cryptosporidium, norovirus and Salmonella — and see how each is detected.
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What is Cyclospora?
A microscopic protozoan parasite (Cyclospora cayetanensis) that infects the small intestine.
Is Cyclospora a bacteria or a parasite?
A parasite — a protozoan, not a bacterium or virus.
Is Cyclospora contagious?
Not person-to-person; shed oocysts need 1–2 weeks to become infectious.
Where is Cyclospora found?
Endemic in tropical/subtropical regions; reaches North America via imported produce and travel.
How do you get infected?
By swallowing sporulated oocysts in contaminated food or water. See the current outbreak and the symptoms it causes.
Sources & further reading
- U.S. Centers for Disease Control and Prevention — Cyclosporiasis (Cyclospora).
- Public Health Agency of Canada — Cyclosporiasis (Cyclospora).
- Mayo Clinic Laboratories — stool parasite testing (why routine O&P can miss Cyclospora).
Outbreak figures reflect the named authorities as of the dates shown and should be re-verified against the current CDC and PHAC data.