As of Tuesday, July 14, 2026, Michigan has emerged as the epicenter of a rapidly expanding outbreak of cyclosporiasis, a severe intestinal illness caused by a parasite. The Michigan Department of Health and Human Services (MDHHS) reported a total of 3,309 confirmed cases statewide. This figure represents a dramatic surge, increasing by more than 600 cases since Monday, when the count stood at 2,640. The state’s case count has more than doubled since Friday, July 10, when officials reported 1,562 cases.
The U.S. Centers for Disease Control and Prevention Connects Midwest States to a Likely Common Source
The outbreak is not confined to Michigan. The U.S. Centers for Disease Control and Prevention (CDC) has epidemiologically linked a large cyclosporiasis outbreak across at least four Midwest states—Michigan, Ohio, West Virginia, and Kentucky—to a likely common source. According to the CDC, 400 people have been connected to the outbreak in those four states, with all individuals reporting that their symptoms began on or after June 22. Beyond the Midwest, the illness has been reported in 31 states. Ohio has reported 434 cases since July 1, including 28 hospitalizations, while New York has reported 470 cases as of Friday.
Dr. Matthew Sims, director of Infectious Diseases Research at Corewell Health, described the scale of the outbreak as unprecedented for the region. This is one of the largest we’ve ever had in Michigan, Sims said. He noted that the spike is reflected in testing data: “In the previous year, we sent a total of 36 tests for Cyclospora; none of them were positive. So far this year, as of yesterday, there were 26, and 15 were positive.”
The Michigan Department of Health and Human Services Investigates Lettuce as a Potential Source
Health officials are working to identify the specific origin of the infections. While no specific type of produce, grower, or supplier has been identified, the MDHHS stated on Monday that “current results point to lettuce or salad greens as a potential source for this outbreak, although other food items cannot be completely ruled out.”
Dr. Natasha Bagdasarian, the chief medical executive for the state, emphasized the importance of transparency during the ongoing investigation. “Although we do not have a definite product identified as the source of the outbreak, we want to let Michiganders know what we have learned so far so they can take steps to protect their families,” Bagdasarian said. “Early information has shown lettuce as a common product that regularly comes up during the investigation. We will continue to provide updates as we learn more.”
Gwen Biggerstaff and Donald Prater Coordinate Federal Trace-back Efforts
Gwen Biggerstaff, the deputy director of the CDC’s Division of Foodborne, Waterborne, and Environmental Diseases, confirmed during a July 14 news conference that the agency is collaborating with state and local health departments and the U.S. Food and Drug Administration (FDA) to collect epidemiologic, trace-back, and laboratory data. Right now we don’t have a specific source identified, Biggerstaff said, noting that agencies are working to triangulate when we might have a common signal across cases.
Donald Prater, the acting deputy commissioner for food at the FDA, added, “We are aware of the signal for lettuce … that’s being noted by our Michigan partners. What I can say at this point is that [we are] continuing our trace-back investigation.”
Cyclosporiasis is an intestinal illness caused by a parasite that infects the small intestine. Patients typically experience watery diarrhea, which can be frequent and sometimes explosive. The illness can last from a few days to over a month if left untreated, and symptoms may relapse. In Michigan, the outbreak has resulted in 44 hospitalizations as of Tuesday. The highest case concentrations in the state are in Monroe, Wayne (which includes Detroit), Lenawee, Washtenaw, Shiawassee, Jackson, Oakland, and Livingston counties.
The CDC had reported 843 confirmed U.S. cases as of Thursday, noting it was aware of 1,500 additional cases that required further analysis to confirm they are domestically acquired cyclosporiasis. Healthcare providers diagnose the illness through stool sample testing. MDHHS has advised that “anyone experiencing gastrointestinal illness, such as sudden and ongoing diarrhea, should contact their health care provider and their local health department.”
Readers concerned about potential exposure or symptoms are advised to consult a qualified healthcare professional. Medical diagnostic testing and appropriate treatment protocols should be managed by licensed clinicians, as symptoms can mimic other gastrointestinal conditions.
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