Michigan Cyclosporiasis Outbreak Tops 300 Cases as Investigators Search for Source

Michigan health officials say the state’s cyclosporiasis outbreak has climbed past 300 confirmed cases, with investigators still trying to identify the source and warning that more illnesses are likely.

The Michigan Department of Health and Human Services said the outbreak had been reported in at least seven counties: Monroe, Lenawee, Washtenaw, Wayne, Livingston, Shiawassee and Jackson. Officials first identified a cluster in Monroe County before the illness spread more broadly across southeast and south-central Michigan.

Dr. Natasha Bagdasarian, MDHHS chief medical executive, said the unusually large number of cases identified in a little more than a week makes it likely that additional infections will be confirmed. Michigan typically sees about 50 cyclosporiasis cases a year.

What officials know so far

MDHHS said the state had more than 300 confirmed cases as of July 2, 2026. The agency has been working with the Michigan Department of Agriculture and Rural Development and local health departments to investigate the outbreak.

People.com reported the updated count on July 3, citing the state’s confirmation. Earlier local coverage on July 1 had put the total at more than 170 cases, underscoring how quickly the outbreak has expanded.

State officials have not publicly identified a specific food, ingredient or distribution channel tied to the illnesses.

What cyclosporiasis is

Cyclosporiasis is a foodborne parasitic illness caused by Cyclospora cayetanensis. It is usually spread through contaminated food or water.

The illness can cause sudden, ongoing diarrhea and may be especially concerning for people who are at risk of dehydration if symptoms continue. Health officials have urged people in Michigan who develop persistent diarrhea to contact a health care provider.

If multiple people in the same household become sick, officials say they should also contact their local health department.

How the outbreak developed

The first public alerts came after Monroe County health officials identified a cluster of cases on June 29. By July 1, MDHHS was already warning that more cases were likely. On July 2, the state confirmed the outbreak had passed 300 cases.

That pace is notable because cyclosporiasis is not a routine issue in Michigan at this scale. The state’s current count is far above its usual annual total and suggests ongoing exposure may still be occurring somewhere in the food chain.

Why it matters

A growing outbreak without a confirmed source leaves residents exposed while investigators continue interviews, testing and traceback work. State and local health agencies are trying to determine whether the illnesses are linked to one product, one distribution channel or multiple clusters.

The Michigan outbreak also comes as the CDC has been tracking a separate multi-state cyclosporiasis investigation. In that federal tally, the agency reported 145 cases across 17 states as of June 16, though Michigan was not included because its surge was reported later.

For now, the main public-health concern is continued spread before investigators can identify the source and stop new exposures. That makes further case-count updates and any source identification the most important developments to watch next.