Michigan’s cyclosporiasis outbreak has surpassed 2,600 cases, state health officials said July 13, making it the hardest-hit state in a national outbreak that has strained hospital lab testing.
The Michigan Department of Health and Human Services reported 2,640 total cases as of July 13, up from 992 as of July 8 and 170 as of June 30.
As of July 9, 44 patients had been hospitalized. The source of the outbreak has not been identified, but state officials said preliminary findings indicate lettuce or salad greens are the primary source.
Cases are concentrated in southeast Michigan. Wayne, Washtenaw, Monroe and Oakland counties have reported the most cases, at 339, 290, 258 and 192, respectively, and adults ages 20 to 49 account for more than half the total.
Nationally, the CDC had confirmed 1,645 domestically acquired cases across 34 states between May 1 and July 14, as well as 141 hospitalizations and zero deaths. The agency said it is aware of more than 5,100 additional reports that require further review to confirm domestic acquisition — meaning state tallies such as Michigan’s run well ahead of the federal count.
The surge has outpaced laboratory capacity. At Toledo, Ohio-based ProMedica Health System, testing turnaround times stretched from about 24 hours to two or three days as demand climbed, Brian Kaminski, MD, the system’s vice president of medical affairs, told NBC News in a July 7 report. Dr. Kaminski said physicians may need to begin treating patients based on symptoms alone if delays persist.
Cyclosporiasis is caused by a parasite typically linked to contaminated fresh produce and does not spread person to person. It is treated with antibiotics but can cause weeks of illness if left untreated.
The outbreak comes a year after the CDC scaled back mandatory cyclospora surveillance in July 2025 as part of reductions to its Foodborne Diseases Active Surveillance Network, a change food safety experts have warned could make outbreaks harder to detect and track.
The CDC, which expects counts to keep climbing given a roughly six-week lag between illness onset and reporting, said it is working with states to reconcile the numbers as more cases are confirmed.
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