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PRIORITY DISEASECyclospora cayetanensis · Parasite
Cyclosporiasis
Cyclosporiasis is an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis. In the US it spreads almost entirely through fresh produce — basil, cilantro, salad mixes, berries — contaminated with the parasite. Outbreaks recur every year and are widely under-recognized.
Transmission
Eating fresh produce or water contaminated with the parasite. It is NOT spread person-to-person — the parasite needs days to weeks in the environment to become infectious.
Incubation
About 1 week (2–14 days) after exposure.
Seasonality
Strongly seasonal in the US: cases climb sharply from May through August, tracking the fresh-produce growing and import season.
Symptoms
- Watery diarrhea (often explosive, weeks-long if untreated)
- Loss of appetite and unintended weight loss
- Stomach cramps, bloating and increased gas
- Nausea, fatigue, and low-grade fever
- Relapsing symptoms that can wax and wane for weeks
Prevention
- Wash all fresh produce thoroughly under running water
- Be cautious with imported fresh herbs and pre-packaged salad mixes
- Treatment is antibiotics (TMP-SMX) — see a doctor for prolonged watery diarrhea
- Routine washing helps but does not fully guarantee removal — source safety matters
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