Cyclospora
Every few summers, the same headline: Cyclospora outbreak linked to imported raspberries, cilantro, or salad mix. This parasite is the produce industry’s recurring seasonal headache — and its biology explains why washing doesn’t solve it.
Taxonomy & characteristics
- Cyclospora cayetanensis; coccidian protozoan, related to Cryptosporidium. The oocyst needs days to weeks in the environment to sporulate and become infective — so direct person-to-person spread is rare; it’s an environmental/food vehicle.
- Oocysts resist chlorination and many sanitizers; they cling to produce surfaces. Washing reduces but doesn’t reliably eliminate them.
- Illness: watery diarrhea, often prolonged and relapsing over weeks; distinctive in lasting far longer than viral gastroenteritis.
Sources & high-risk foods
- Reservoir: humans (fecal contamination in growing regions); no significant animal reservoir.
- High-risk: imported berries, cilantro, basil, snow peas, salad mixes — produce from regions with poor sanitation, eaten raw.
Control measures
- Supply chain: know your growing region’s sanitation; audits of farms in endemic areas.
- Water: safe irrigation and pesticide-mix water — contaminated spray water is a documented vehicle.
- Consumer: thorough washing helps but isn’t a guarantee; vulnerable consumers should note the seasonal pattern.
Seasonality and traceback
Cyclospora outbreaks are strikingly seasonal — late spring through summer in North America — matching import patterns of fresh produce from endemic regions. Traceback is notoriously difficult: long incubation (a week or more), prolonged illness that patients don’t always associate with a specific meal, and a parasite that can’t be easily fingerprinted to a farm. FDA and CDC investigations have repeatedly converged on imported cilantro, basil, raspberries, and salad mixes. For importers, the control is supply-chain knowledge: which farms, what water sources, what sanitation infrastructure. Testing produce for Cyclospora is possible but not routine — prevention rests on growing-region hygiene, not border screening.
Sources: CDC; FDA.