A nationwide outbreak of the intestinal parasite Cyclospora has surged to become the largest ever recorded in the United States, with state health departments reporting close to 5,000 cases—far exceeding the 843 confirmed by the Centers for Disease Control and Prevention. Michigan alone has logged 3,309 infections and 44 hospitalisations as of Tuesday, more than sixty times its typical annual count. The previous national record, set in 2019, stood at roughly 4,700 cases. Viewed from Washington, the discrepancy between federal and state tallies reflects a deliberate scaling back of surveillance: last July the CDC removed cyclosporiasis from the mandatory FoodNet reporting system, making case tracking optional for participating states.

Federal and state investigators are examining whether the fast-food chain Taco Bell played a role in the outbreak, after several of its Detroit-area restaurants posted signs saying they could not sell lettuce, cilantro, onion, pico de gallo or guacamole “due to a nationwide recall.” The company told CBS News it had “voluntarily and temporarily removed limited ingredients at select restaurants as a precautionary measure,” while stressing that no public health authority has confirmed a link to its supply chain. Michigan’s chief medical executive, Natasha Bagdasarian, said early interviews point to lettuce or salad greens as a common exposure, though no specific grower, brand or distributor has been identified. Officials in Ohio, New York and more than two dozen other states are conducting parallel traceback investigations, and the Food and Drug Administration is examining multiple produce items and establishments named by patients.

The Cyclospora cayetanensis parasite causes cyclosporiasis, an intestinal infection marked by watery, sometimes explosive diarrhoea that can persist for weeks if untreated. Symptoms typically emerge one to two weeks after consuming contaminated food or water, a delay that complicates efforts to pinpoint the source. The parasite is resistant to chemical disinfectants and adheres tightly to produce; cooking to at least 70°C is the only reliable way to kill it. While the illness is rarely fatal, the CDC reports 86 hospitalisations nationwide, and the American Medical Association warns that relapses are possible. Health officials in Michigan have advised consumers to buy whole heads of lettuce, discard outer leaves and wash the remainder thoroughly, though they caution that washing alone may not remove the parasite.

The scaling back of FoodNet surveillance has drawn sharp criticism from public health experts, who argue it has left investigators with fewer tools to detect and contain foodborne threats. A former FoodNet official noted that the programme previously collated detailed patient and food-source data across states, a capacity now diminished. The CDC maintains that it continues to gather cyclospora data through other systems and that overall food-safety funding has remained stable. Investigators now await the results of traceback analyses that could identify a common grower or distributor—a step that would trigger the first formal recall in this outbreak and clarify whether Taco Bell’s precautionary withdrawal was an isolated measure or a response to a wider contamination event.