Hamilton County health officials reported an increase in cyclosporiasis cases this week, as a multistate outbreak of the gastrointestinal illness continues to spread across the United States. According to the latest update from Hamilton County Public Health, there are now 17 total reported cases, rising from 16 cases earlier in the week. The current count includes 12 confirmed cases, one probable case, and four suspected cases.
Cyclosporiasis is caused by the microscopic parasite *Cyclospora cayetanensis*. While the illness is typically not life-threatening, it can cause significant health complications and discomfort. Hamilton County health officials noted a statistically significant increase in residents seeking care for gastrointestinal issues, with more than 40 people reporting symptoms such as diarrhea, vomiting, abdominal pain, blood in stool, fatigue, and general concerns regarding food poisoning.
National Scope and Surveillance Challenges
The outbreak has reached a significant scale, impacting 34 states. As of July 13, the Centers for Disease Control and Prevention (CDC) reported 1,645 confirmed domestic cases. When including suspected cases that require further analysis, the total number of individuals impacted is estimated to be more than 5,100.
Health experts emphasize that these figures likely represent an underestimate of the true impact. The CDC’s tracking system has been scaled back, and the specialized diagnostic testing required to identify the parasite is not always performed. Because the illness is frequently underdiagnosed and underreported, the actual number of infections is likely higher than official data suggests.
This year’s surge is notably higher than the previous year; by mid-July 2025, the nation had recorded only 249 cases. Of the 1,645 confirmed cases with available data this year, 141 individuals (9%) required hospitalization. No deaths have been reported to date.
Understanding the Parasite and Transmission
Cyclospora is a single-celled parasite transmitted through the consumption of food or water contaminated with human waste. It is not generally spread directly from person to person. A unique challenge in tracking this parasite is its lifecycle: once excreted, it requires one to two weeks in the environment to develop into an infectious state.
Previous outbreaks have historically been linked to fresh produce, including raspberries, basil, cilantro, and various salad mixes. While investigations are ongoing, Michigan health officials have pointed to lettuce and other salad greens as potential sources that frequently appear during investigations. However, no single definitive source has been confirmed for the current multistate outbreak.
Challenges in Food Safety and Prevention
The investigation into the source of the outbreak is complicated by the nature of modern agricultural systems. A significant portion of U.S. produce is irrigated with surface water, which can be contaminated by leaking sewer or septic systems. Furthermore, current food safety regulations allow for the harvest of produce shortly after water is applied, potentially leaving little time for contaminants to dissipate.
Prevention Guidelines
To mitigate the risk of infection, health officials provide the following recommendations for handling produce:
| Action | Best Practice |
| :— | :— |
| Handwashing | Wash hands with soap and water before and after preparing raw produce. |
| Cleaning | Rinse fruits and vegetables thoroughly under running water. |
| Scrubbing | Use a clean produce brush on firm items like melons and cucumbers. |
| Preparation | Cut away any damaged or bruised sections of fruits and vegetables. |
| Storage | Refrigerate cut, peeled, or cooked produce within two hours. |
Health officials note that items labeled “prewashed” do not require additional cleaning at home. Because chemical disinfection is often ineffective against the *Cyclospora* parasite, the CDC suggests that advanced methods like microfiltration, ozone, or UV treatments may be necessary to reduce parasite populations in water supplies.
Clinical Guidance for Diagnosis and Treatment
The CDC advises clinicians to consider cyclosporiasis in patients presenting with prolonged or relapsing watery diarrhea, particularly during the peak season of May through August. Because routine ova and parasite (O&P) exams may fail to detect the parasite, providers are encouraged to specifically request *Cyclospora*-specific testing or use molecular (PCR-based) diagnostics. Patients are advised to maintain hydration, as the illness can lead to complications such as malabsorption, cholecystitis, and reactive arthritis if left untreated. Residents experiencing symptoms are urged to contact their healthcare provider for evaluation.
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