A parasitic illness spreading through Michigan and Ohio has now sickened more than 1,400 people, and public health investigators still cannot say what food is carrying it.
The outbreak of cyclosporiasis, a gut infection best known for causing what the CDC bluntly calls explosive diarrhea, is already the largest of its kind Michigan has ever recorded, and it is still growing.
The Numbers Keep Climbing
Michigan is carrying most of the caseload. Forbes reported that the two states have logged a combined total above 1,400 cases, and the Michigan Department of Health and Human Services counted 1,251 cases statewide as of July 9. Ohio’s health department has reported at least 177 cases this year, nearly all of them arriving since late June, which is exactly the acceleration pattern you do not want to see in a foodborne outbreak.
The human toll so far: at least 72 hospitalizations across the two states, 44 of them in Michigan, and no deaths. Michigan’s chief medical executive, Dr. Natasha Bagdasarian, has called it the largest cyclosporiasis outbreak in the state’s history, with cases reported across at least 21 counties.
What Cyclospora Actually Does
Cyclospora is a microscopic parasite that hitches a ride on contaminated food, most often fresh produce, and sets up shop in the small intestine. The resulting illness brings watery diarrhea, cramping, fatigue, and appetite loss that can drag on for weeks if untreated. The good news is that it is rarely life threatening and responds to a common antibiotic. The bad news is that it is miserable, easy to misdiagnose, and has an incubation period of about a week, which means every day without a source identified is another week of cases already baked in.
That lag is the quiet villain of this story. By the time a cluster shows up in state dashboards, the contaminated product has been on shelves, in salads, and through kitchens for days.
The Source Hunt Is the Hard Part
Here is the structural problem underneath the case count: investigators have not identified a grower, a supplier, or even a specific type of produce. The Detroit News reported that Michigan officials are racing to trace the outbreak while their leading hypothesis remains produce-related, and the Associated Press noted in a report carried by ABC News that no source had been confirmed as cases passed the 1,000 mark.
Why is this so hard? Cyclospora traceback is notoriously slow because fresh produce moves fast and dies young. A bag of greens or a basket of berries is bought, eaten, and discarded long before anyone gets sick, so investigators are reconstructing supply chains from receipts and interviews rather than testing the actual food. Past national outbreaks took weeks to pin on bagged salad mixes and imported herbs, and some were never definitively solved.
It is also worth saying what state officials mostly will not: the federal food-safety net that states lean on for multistate tracebacks has been thinned by years of budget and staffing cuts, and an outbreak sprawled across 21 counties and two states is precisely the scenario where federal lab capacity and coordination speed determine how long the case curve keeps climbing. Food recalls have been a steady drumbeat this year, and as we saw with the Class I salmonella recall of Utz and Zapp’s chips, the system usually works backward from illness to product. The slower that process runs, the bigger the human denominator gets.
What You Can Actually Do
The practical advice is unsatisfying but real. Wash produce thoroughly, though the CDC cautions that washing alone may not remove cyclospora. Cooking kills it, so cooked vegetables are safe. If you are in Michigan or Ohio and develop diarrhea lasting more than a few days, ask your doctor specifically about cyclosporiasis testing, because it does not show up on a standard stool panel unless someone looks for it, and the treatment is a cheap, widely available antibiotic.
The number to watch in the next two weeks is not the case count. It is whether investigators name a product. If they do, this outbreak ends quickly. If they do not, 1,400 becomes a floor, not a ceiling.