Michigan reports 228 cyclosporiasis cases in ten days, far exceeding annual average
State health officials have confirmed 228 cases of cyclosporiasis in Michigan since June 22, a number four times higher than the typical yearly total, while the source of the outbreak remains unknown.
State health officials in Michigan have confirmed 228 cases of cyclosporiasis, a parasitic infection that causes gastrointestinal symptoms, reported between June 22 and July 1. The figure is roughly four times the state’s usual annual total of about 50 cases. The majority of cases have been identified in Monroe County, which alone accounts for 92 infections, with additional cases reported in Washtenaw, Wayne, Livingston, Shiawassee, Lenawee, Jackson and 15 other counties, according to the Michigan Department of Health and Human Services (MDHHS).
MDHHS spokeswoman Lynn Sutfin said the source of the outbreak has not yet been determined and it is unclear whether all cases are linked to a single source. The department expects more cases to be reported given the rapid spread.
"Individuals concerned about sudden gastrointestinal illness should contact a health care provider," Sutfin said. "Cyclospora infections can be treated with antibiotics and individuals experiencing diarrheal illness or vomiting are encouraged to hydrate, particularly during the high temperatures expected this week."
The parasite Cyclospora cayetanensis is typically associated with contaminated water or food, especially fresh produce, and is more common in developing regions. The Michigan Department of Agriculture and Rural Development is assisting in the investigation and has urged residents to wash produce, remove damaged portions, and refrigerate cut items.
Symptoms can appear two days to two weeks after exposure and include watery diarrhea, abdominal cramps, nausea, vomiting, loss of appetite, weight loss and low-grade fever. The CDC notes that person-to-person transmission is unlikely and that proper food handling can reduce risk.
The surge follows a period of relatively low incidence in the state, which recorded 56 cases in 2022, 43 in 2023, 41 in 2024 and 54 in 2025. Cases have ranged in age from 8 to 84 years, with a median age of 41. Nearby Ohio’s Toledo-Lucas County Health Department also reported an increase, estimating 65 cases in its jurisdiction.
The CDC has documented about 145 cyclosporiasis cases across 17 states since May 1, with 20 hospitalizations.
