I think I ate bad lettuce. What should I do? How to avoid a serious cyclospora illness, according to experts. Cyclospora infection spreads when someone eats food, usually fresh produce, or drinks water that’s been contaminated with the parasite. It then travels through the gut where it attaches to the small intestine.Anisha Chopra / Getty ImagesAug. 4, 2026, 1:00 PM EDTBy Gina VivinettoThis summer’s cyclospora outbreak has triggered worries about contracting a nasty foodborne gastrointestinal illness caused by the microscopic parasite.Just a moment.We are getting your experience ready.