A patient arrives after two weeks of relentless watery diarrhea, sometimes 20 episodes a day. She has lost weight and cannot keep fluids down. Her stool tests come back negative. Unless someone thinks to order an assay that includes Cyclospora cayetanensis, she may leave without a diagnosis and stay ill for weeks longer.

Cyclospora is easy to miss in a clinic. Many routine stool tests do not include it, so a clinician must consider the parasite before the laboratory will look for it. You find it on purpose, or you do not find it.

Last year the federal government arranged for the country to miss it too. On 1 July 2025, the CDC downgraded FoodNet, the active surveillance network it has run with the FDA, the USDA and 10 state health departments since 1995, making tracking of Cyclospora optional at its sites, along with listeria, campylobacter, shigella, vibrio and yersinia. Of the eight pathogens it was built to watch, six were downgraded to optional. Salmonella and E coli remained mandatory. The change arrived with budget cuts and no public announcement, and was reported almost two months later, when a journalist asked.

This summer, cyclosporiasis is moving through the US food supply on a scale not seen in years. As of 15 July, the CDC had confirmed 1,645 domestically acquired cases across 34 states, with 141 hospitalizations, and said it was aware of more than 5,100 further cases awaiting analysis. Michigan, which in a normal year records 40 to 50 cases, has reported........

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