Michigan Cyclosporiasis Outbreak Surges Past 1,200 Cases, Source Still Unknown

Michigan is experiencing an unprecedented outbreak of cyclosporiasis, a parasitic infection caused by Cyclospora cayetanensis that leads to severe, prolonged watery diarrhea often described as 'explosive.' As of July 9, 2026, the Michigan Department of Health and Human Services (MDHHS) reported 1,251 cases since June 22, a dramatic increase from 170 cases just days earlier and roughly 13-25 times the state's typical annual total of 40-50 cases.[1][2]

The surge is concentrated in eight southeast Michigan counties—Monroe, Lenawee, Washtenaw, Wayne, Shiawassee, Jackson, Oakland, and Livingston—with cases continuing to climb daily. MDHHS and partners are investigating, but no specific produce grower, supplier, or type has been identified as the source.[3]

Nationally, the CDC has tracked 145 U.S.-acquired cases across 17 states from May 1 to mid-June (excluding much of Michigan's spike), with 20 hospitalizations and no deaths. Neighboring areas like northwest Ohio have also reported hundreds of cases, raising questions about shared food supply chains.[4][5]

Symptoms include debilitating diarrhea (up to dozens of episodes daily), cramps, nausea, vomiting, fatigue, and fever lasting days to weeks, sometimes relapsing. The parasite spreads via contaminated fresh produce or water and is not person-to-person transmissible. Treatment involves the antibiotic trimethoprim-sulfamethoxazole. Officials recommend thorough washing of fruits and vegetables.[6]

This outbreak highlights vulnerabilities in produce safety monitoring and has prompted enhanced recommendations for commercial kitchens in affected areas.