Health officials are investigating a surging outbreak of cyclosporiasis, a parasitic infection causing severe, “explosive” diarrhea. As of July 14, the CDC reports nearly 7,000 cases across 34 states. A multistate cluster in Michigan, Ohio, West Virginia, and Kentucky has been epidemiologically linked to a likely common food source.
Midwest Outbreak and the Search for a Source
The current surge in cyclosporiasis—a gastrointestinal illness caused by the Cyclospora cayetanensis parasite—has prompted urgent investigations by federal and state health agencies. While cases are rising nationally, a specific cluster involving at least 400 people across Michigan, Ohio, West Virginia, and Kentucky has drawn particular scrutiny.
In Michigan, which has reported over 3,300 cases since late June, health authorities are focusing on fresh produce. We are aware of the signal for lettuce … that’s being noted by our Michigan partners,
said Donald Prater of the FDA during a recent media briefing. State health officials have advised residents to purchase whole heads of lettuce, discard outer layers, and wash the remaining leaves thoroughly to reduce potential exposure.
State-by-State Impact and Reporting Discrepancies
The scale of the outbreak varies significantly by region. Michigan remains the hardest-hit state, with the Department of Health and Human Services recording a sudden and large
increase compared to its typical annual average of 40 to 50 cases.
For more on this story, see Cyclosporiasis Outbreak Hits 1,600 U.S. Cases as Officials Probe Water Source.
| State | Reported Cases (2026) |
|---|---|
| Michigan | 4,312 |
| Ohio | 1,274 |
| Illinois | 277 |
| North Carolina | 240 |
These figures often lag behind real-time infection rates. The CDC warns of a roughly six-week reporting delay between the onset of symptoms and the inclusion of a case in national data. Furthermore, because many individuals with mild symptoms do not seek medical care or undergo the specific stool testing required to detect Cyclospora, the true number of infections is likely significantly higher than official counts suggest.
Symptoms and Clinical Considerations
The parasite infects the small intestine, triggering a distinct and uncomfortable clinical presentation. Dr. Peter Chin-Hong, an infectious disease specialist, explained that the parasite destroys the intestinal lining, preventing the absorption of water and nutrients. This leads to sudden and forceful high-volume diarrhea that has been described as ‘explosive.’
Symptoms typically manifest between 2 and 14 days after exposure. While generally not life-threatening for individuals with healthy immune systems, the primary risk is severe dehydration. Physicians are currently being advised to consider cyclosporiasis in patients presenting with prolonged or relapsing watery diarrhea, as routine parasite exams may fail to identify the organism.
Precautionary Measures and Future Outlook
As the investigation proceeds, some commercial entities have begun adjusting operations. Taco Bell confirmed it had voluntarily and temporarily removed limited ingredients at select restaurants as a precautionary measure
amid the ongoing federal trace-back investigation. Federal officials, including Gwen Biggerstaff of the CDC, noted that the agency expects cases to continue rising possibly through the end of August, which is the end of the cyclosporiasis season.
This follows our earlier report, Cyclospora Outbreak Hits 34 States as CDC Searches for Food Source.
While previous outbreaks have been linked to imported produce like basil, cilantro, and raspberries, recent years have seen the parasite detected in domestically grown crops. Dr. Natasha Bagdasarian, Michigan’s chief medical executive, characterized the current surge as highly unusual.
For those experiencing persistent gastrointestinal symptoms, health authorities recommend contacting a healthcare provider to request specific stool testing and to monitor fluid intake closely to prevent dehydration.
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