Michigan is in the middle of the largest outbreak of a diarrheal illness in the state’s history, and health officials still haven’t been able to pin down exactly where it’s coming from. As of this week, more than 1,200 people in the state have been sickened, with dozens hospitalized — and the outbreak isn’t staying within state lines. Here’s what’s actually known, why it’s proving so hard to trace, and what health officials are recommending in the meantime.
Key Takeaways
- Michigan has confirmed 1,251 Cyclospora cases as of July 9 — its largest outbreak on record — with 36 hospitalizations reported as of July 8.
- Ohio has 177 confirmed cases as of July 2, and investigations are open in 28 other states.
- Investigators haven’t been able to trace the source yet, since Cyclospora is difficult to test for and the incubation period can run one to two weeks.
- Officials currently recommend buying whole heads of lettuce instead of pre-washed bagged salad and cooking leafy greens when possible.
- Cyclosporiasis is treated with antibiotics — see a doctor if diarrhea persists for an extended period rather than waiting it out.
The Numbers Behind the Outbreak
As of July 9, Michigan’s Department of Health and Human Services had confirmed 1,251 cyclosporiasis cases statewide since the outbreak began on June 22 — up from 992 just a day earlier, showing how quickly the count keeps climbing. As of July 8, 36 hospitalizations had been linked to the illness. In a typical year, Michigan sees roughly 50 cases total, making this the largest outbreak of its kind in the state’s history. Those diagnosed range in age from 8 to 84, with a median age of 41, and no deaths have been reported.
The outbreak isn’t confined to Michigan. Neighboring Ohio has its own confirmed cases — reported at 177 as of July 2 — and investigations into similar illness are currently underway in 28 other states.
What’s Causing It
The culprit is Cyclospora, a microscopic single-celled parasite that lives in fecal matter and typically makes its way into food when crops are irrigated with contaminated water. It thrives in warm weather, which is part of why cases tend to climb during summer months. Past outbreaks have been traced back to sources like imported raspberries, basil, snow peas, and bagged salad mixes — but as of now, no specific grower, supplier, or produce type has been confirmed as the source of this particular outbreak.
Why This Outbreak Is Especially Hard to Trace
A few factors are making this investigation unusually difficult. Cyclospora is notoriously hard to culture in a lab, and some standard tests don’t reliably detect it. On top of that, the incubation period can run one to two weeks, so by the time someone gets sick, the food that caused it is often long gone — and a single bag of salad can be sourced from several different farms, which only adds to the difficulty of pinpointing an exact origin. Health officials are now using genetic fingerprinting on samples to check whether cases share a common source.
What Health Officials Are Recommending Right Now
Because the source hasn’t been identified yet, guidance has gotten more cautious. Officials are currently advising people to buy whole heads of lettuce rather than pre-washed bagged salad, discard the outer two to three leaves, and wash the remaining leaves thoroughly under running water — cooking leafy greens when possible, since that’s considered the safest option. The same applies to cilantro and basil: separate the leaves, wash thoroughly, and cook when you can. For green onions, trim the root end, remove the outer layer, and wash well. As a general rule, cooking food to 158°F or higher kills the parasite, and all fresh produce should be washed under running water even if you plan to peel it. Cut produce should also be refrigerated promptly.
Symptoms to Watch For
The hallmark symptom is watery diarrhea with frequent, sometimes explosive bowel movements, often accompanied by cramping, bloating, and fatigue. Left untreated, symptoms can last anywhere from a few days to over a month, and can even relapse. Ordinary stomach bugs tend to pass quickly; this one typically doesn’t. If diarrhea drags on for an extended stretch, that’s the point to see a doctor rather than wait it out.
The Good News: It’s Treatable
Despite how unsettling the case numbers look, cyclosporiasis is treated with antibiotics, along with rest and staying hydrated. Health officials aren’t asking people to panic — the message is to stay cautious with produce, pay attention to symptoms, and seek medical care promptly if diarrhea persists rather than assuming it will pass like a typical stomach bug.
Frequently Asked Questions
Do I need to stop buying salad and berries entirely?
Not entirely, but current guidance leans more cautious than usual: officials recommend buying whole heads of lettuce instead of pre-washed bagged salad, discarding the outer leaves, washing thoroughly, and cooking leafy greens when possible, since rinsing alone may not remove this parasite.
Why can’t investigators find the source of this outbreak?
Cyclospora is notoriously difficult to grow in a lab and some tests miss it entirely. Combined with a one-to-two-week incubation period and produce that’s often sourced from multiple farms, tracing an exact origin has proven especially difficult this time.
Is this outbreak spreading beyond Michigan?
Yes. Neighboring Ohio has 177 confirmed cases as of July 2, and health investigations are currently open in 28 other states.
Is this illness treatable?
Yes — there is an effective antibiotic treatment once it’s diagnosed. The key is seeing a doctor if diarrhea persists for an extended stretch rather than assuming it will pass like a typical stomach bug.
Quick Start Checklist
- ☐ Skip pre-washed bagged salad for now
- ☐ Buy whole heads of lettuce and discard the outer leaves
- ☐ Cook vegetables when possible, since rinsing alone may not be enough
- ☐ Wash raspberries, basil, and other crevice-heavy produce extra thoroughly
- ☐ Refrigerate cut produce right away
- ☐ See a doctor if diarrhea persists for an extended period — it’s treatable with antibiotics
Sources:
Michigan Department of Health & Human Services — official outbreak page with daily-updated case counts and produce safety recommendations
https://www.michigan.gov/mdhhs/keep-mi-healthy/infectious-diseases/infectious-disease-outbreaks
ClickOnDetroit — “Cyclosporiasis outbreak: Cases in Michigan rise to over 1,200” (July 9, 2026)
https://www.clickondetroit.com/news/local/2026/07/09/cyclosporiasis-outbreak-cases-in-michigan-rise-to-over-1200/
Disclaimer: This article is for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Case figures reflect the most recently reported numbers as of publication and may have changed since. If you’re experiencing persistent diarrhea or other concerning symptoms, contact a healthcare provider promptly. For the latest official guidance and case counts, consult the Michigan Department of Health and Human Services or the CDC.