CDC Says Cyclosporiasis Outbreaks in Multiple States May Be Linked

Cyclosporiasis outbreaks in four Midwestern states are likely epidemiologically linked, part of an unusually large wave of cases in at least 34 states, CDC officials said.

While the agency still hasn’t identified a specific culprit behind the likely foodborne illnesses, cases in Michigan, Ohio, Kentucky, and West Virginia are likely part of a single outbreak, said Gwen Biggerstaff, ScD, deputy director of CDC’s Division of Foodborne, Waterborne, and Environmental Diseases.

This year’s case count “is a much higher number than we typically see in a cyclosporiasis season,” Biggerstaff noted during a media briefing Tuesday. “It’s a very big shift from what we’ve seen in previous seasons.”

Michigan alone has reported 3,309 cases as of July 14, with 44 reported hospitalizations.

Since May 1, the CDC said it has received 1,645 confirmed reports of cyclosporiasis cases, with further analysis needed for 5,100 more cases before confirmation. The tally of confirmed cases is more than five times greater than the 249 cases reported by this time last year. The CDC expects to see case numbers rise as the season progresses, possibly through the end of August, Biggerstaff said.

The broader rise in confirmed cases across 34 states points to more than one outbreak, said Donald Prater, DVM, the FDA’s acting Deputy Commissioner for Food, during the briefing. “I think we’re looking at multiple clusters and subclusters.”

The FDA is aware of a “signal” pointing to lettuce as a possible outbreak source in Michigan, he noted. “We’re continuing to trace multiple items, including lettuce.”

CDC Cut Cyclospora Reporting Requirement Last Year

This year’s case spike comes a year after program cuts led by HHS Secretary Robert F. Kennedy Jr. prompted the CDC to remove the microscopic parasite Cyclospora from a list of eight pathogens that states were mandated to report to the Foodborne Diseases Active Surveillance Network, or FoodNet. As of July 2025, reporting is optional for all pathogens except Salmonella and Shiga toxin-producing E. coli.

While states are no longer required to report Cyclospora infections in FoodNet’s slimmer list, Biggerstaff said that states can still report cyclosporiasis data as part of national surveillance. “So, the data we have for cyclosporiasis for this outbreak are the same as we’ve had for all of the other seasons — we use the same systems and the same processes,” she noted.

A key surveillance gap occurs when people don’t seek care, “or, when they do seek care, they aren’t tested,” Biggerstaff explained. If people are experiencing symptoms, they should talk with their doctor about it so they can get tested, and their cases can be reported and investigated, she added.

How Clinicians Should Manage Cases

The outbreaks have prompted the CDC to issue a Health Alert Network (HAN) advisory on the domestic outbreak and to roll out a cyclosporiasis website that will feature regular updates. The FDA will also provide cyclosporiasis updates every Wednesday, Prater said.

The HAN advisory recommends that clinicians consider a cyclosporiasis diagnosis when a patient has prolonged or relapsing watery diarrhea, particularly during the May-August cyclosporiasis season. Cyclospora lab testing on patient stool samples should be requested, given that routine ova and parasite exams might miss detection. Molecular diagnostic testing can improve Cyclospora detection.

Along with diarrhea, symptoms like cramping and nausea can occur about 1 week after consuming infected food or water. Cases are more common during warmer months when people are more often consuming certain fresh produce — especially bagged lettuce, fresh berries, and herbs like cilantro and basil. Cyclosporiasis usually resolves on its own for most people, though in some cases it may need to be treated with antibiotics.

Immunocompetent cyclosporiasis patients ages 2 months or older should receive 7 to 10 days of trimethoprim-sulfamethoxazole, with longer treatment for immunocompromised patients.