See map tracking spread of ‘explosive’ diarrhea illness across US
Tracking the Rapid Expansion of Cyclosporiasis Across American States
See map tracking spread of explosive - A parasitic infection responsible for severe gastrointestinal distress is experiencing a significant surge throughout the United States, with health officials actively investigating the expanding outbreak. Cyclosporiasis, which produces intense stomach discomfort and is frequently linked to contaminated fresh produce and herbs, has now affected at least 843 individuals across 31 states since the beginning of May, according to recent figures compiled by the Centers for Disease Control and Prevention alongside state health departments.
Michigan currently faces an especially intense situation, with its infection count already exceeding the entire 2025 total by more than fourteen times. Several other states have similarly reported case numbers climbing into the hundreds, suggesting a broader pattern of transmission than initially apparent.
Understanding the Discrepancy in Case Numbers
State-level reports indicate a much larger outbreak than what appears on the CDC's official surveillance dashboard, which has historically updated its figures on a monthly basis. The most recent CDC publication from July 9 continues to trail behind individual state reports as the federal agency works through the process of verifying each infection. At present, investigators have found no evidence connecting all the case clusters to one common origin point.
The gap between federal and state numbers stems from different counting methodologies. The CDC only includes laboratory-confirmed cases that occurred domestically on or after May 1, excluding individuals who traveled internationally within the two weeks before becoming ill. Meanwhile, many states report year-to-date totals or combine both local and international infections without distinction.
"CDC is aware that states are likely to report higher case counts of cyclosporiasis than reflected in CDC data and is working closely with states to update numbers as additional cases are confirmed," the agency explained in a statement accompanying its surveillance page. "Since May 1, 2026, CDC has received reports of 843 confirmed domestic cases of cyclosporiasis and is aware of more than 1,500 cases that require further analysis to confirm the illness as domestically acquired cyclosporiasis."
Demographics and Timeline of the Outbreak
Among the 843 Americans who contracted the illness domestically, 86 required hospitalization while no fatalities have been recorded. The affected population spans from five to eighty-eight years old, with a median age of forty-four. According to CDC guidance, the cyclosporiasis season typically runs from May 1 through the end of August, marking the period when the United States usually experiences elevated infection rates.
These federal figures exclude hundreds of additional cases that individual states have documented. For instance, while the CDC listed between 161 and 300 cases in Michigan as of July 9, state health officials communicated to USA TODAY that Michigan had reached 700 total cases by July 6.
"We assume a 6-week reporting lag between illness onset and case reporting to CDC; therefore, we anticipate that case counts will continue to rise as data are received," the portal page explains.
Due to the accelerating pace of new infections, the CDC has announced plans to collect state data on a weekly basis rather than the previous monthly schedule.
What Is Cyclosporiasis?
Cyclosporiasis represents a parasitic infection triggered by the organism Cyclospora cayetanensis, commonly referred to as cyclospora. The condition produces gastrointestinal symptoms frequently mistaken for food poisoning, including diarrhea, nausea, and vomiting. While the experience is decidedly unpleasant, the illness is not typically associated with mortality, and numerous cases remain unreported because affected individuals recover at home without seeking medical attention.
The hallmark symptom involves watery, frequent, and occasionally explosive diarrhea, as noted by both the CDC and Cleveland Clinic. Additional complications may accompany this primary symptom depending on the severity of infection.
When the CDC last provided an update on June 16, the dashboard displayed only 145 cases spread across 18 states. Since that publication, the situation has evolved considerably, with the current count reflecting both domestic infections and 343 additional cases contracted during international travel.
The agency acknowledges that the true scope of the outbreak likely exceeds published numbers, emphasizing that the delay primarily reflects the time required for laboratory testing and confirmation rather than an absence of cases. As testing capacity expands and reporting mechanisms improve, health officials expect the comprehensive picture of this cyclosporiasis surge to become increasingly clear.