Nearly 7,000 people across the United States had confirmed or suspected cyclosporiasis as federal and state authorities investigated an unusual seasonal surge. The Centers for Disease Control and Prevention reported 1,645 confirmed illnesses and another 5,100 cases under review.
At least 30 states in addition to Michigan reported clusters. Michigan accounted for 3,309 confirmed cases in its own system, and federal figures lagged behind state totals because the CDC reviewed each report before adding it. The national investigation recorded 141 hospitalizations among people whose illnesses began in May or later, with no deaths. Patients ranged from age 2 to 95, and 56% were women.
Cyclosporiasis is caused by Cyclospora, a microscopic parasite that can pass from human waste to food through contaminated water or unsafe handling. Symptoms can take as long as two weeks to begin. Severe diarrhoea is characteristic, while fatigue, aches, reduced appetite, bloating and nausea can also occur. Untreated symptoms may continue for weeks.
CDC official Gwen Biggerstaff said about 2,700 cases were normally seen in a year, mostly during summer. The 2026 total was rising sharply, and the agency expected additional reports through August. It alerted clinicians to consider the infection in patients with compatible symptoms.
Federal investigators believed several outbreaks from different sources could be occurring simultaneously. At least 400 cases in Kentucky, Michigan, Ohio and West Virginia might belong to one multistate cluster, but many other illnesses remained outside that group. More than 1,000 Michigan patient interviews repeatedly identified lettuce and salad greens as possible exposures.
No single product, restaurant, retailer or distributor had been confirmed as the source for the national increase, and no recall had been announced. The Food and Drug Administration said it was examining several produce items, including lettuce. Taco Bell temporarily removed limited ingredients from some restaurants as a precaution while saying authorities had not confirmed a link to the chain or a particular supplier.
Because of the long incubation period, patients could be asked to remember food eaten several weeks earlier. Michigan chief medical executive Dr. Natasha Bagdasarian said illness-onset peaks near June 25 and July 7 could point to two ingredient batches, while distribution patterns could expose customers of multiple businesses.
The CDC advised washing produce under clean running water. It said vinegar, commercial washes or soaking did not reliably remove attached parasites; cooking was the only stated method for killing them before consumption. Those precautions did not identify the outbreak source, which remained the central unresolved question behind the combined confirmed and suspected total.
Bactrim was identified as the antibiotic most commonly used for the illness. Treatment information did not change the need for source control, because investigators were tracing Cyclospora exposure through contaminated food or water. The lack of a recall reflected unresolved traceback, not a conclusion that all food then on sale was safe.
