I study pathogens in sewage. Here's how cyclospora could be getting into our food.

Theory Briefing

• Sewage contamination of irrigation water or soil is the leading theory for how cyclospora, a hard-to-kill parasite, reaches fresh produce.
• Cyclospora is notoriously difficult to detect in food and water, which makes tracing outbreaks back to a single source unusually challenging.
• Public health researchers who study pathogens in sewage say the gap between contamination and detection is wide enough for outbreaks to spread before anyone notices.
• The food supply chain's complexity — many hands, fields, and facilities — makes pinpointing exactly where sewage contact occurs a persistent problem.