CDC Investigates Widespread Cyclosporiasis Outbreak
Federal health officials are currently investigating an unusually large and geographically widespread outbreak of cyclosporiasis, an intestinal illness caused by the *Cyclospora* parasite. As of July 14, 2026, the U.S. Centers for Disease Control and Prevention (CDC) has confirmed 1,645 cases across 34 states.
According to Dr. Gwen Biggerstaff, deputy director of the CDC’s Division of Foodborne, Waterborne, and Environmental Diseases, the confirmed case count is likely an underestimate. The agency is currently analyzing at least 5,100 additional potential cases to determine if they are linked to the outbreak. By comparison, the national total for the same period in 2025 was 249 cases.
While no deaths have been reported, 141 patients have required hospitalization. The patients involved in the current outbreak range from 2 to 95 years of age, with a median age of 44, and approximately half are women. Data indicate that all confirmed patients became ill after consuming food within the United States, with no travel reported in the two weeks prior to the onset of symptoms.
Investigation Challenges and Ongoing Efforts
The source of the current outbreak remains unidentified. Donald Prater, the FDA’s acting deputy commissioner for food, acknowledged reports from Michigan identifying lettuce as a potential source, but officials have not confirmed a definitive link to any specific food item. Traceback investigations are ongoing, involving the collection of detailed consumption histories from affected individuals.
The CDC has established a new outbreak investigation notice webpage to track developments, specifically noting a multistate cluster involving Michigan, West Virginia, Kentucky, and Ohio. To improve transparency, the agency plans to update its surveillance and investigation data at least weekly.
The investigation has faced scrutiny regarding the pace of the federal response. Dr. Michael Osterholm, an infectious disease expert at the University of Minnesota, characterized the federal response as falling short of necessary requirements. Additionally, Dr. Thomas Moore of the University of Kansas School of Medicine suggested that delays in identifying the source may be partially attributed to budget and personnel cuts at the federal level, alongside reduced public health infrastructure in various states. U.S. Senator Amy Klobuchar has urged the CDC and FDA to reinstate funding and staffing for food safety programs.
For more on this story, see CDC Investigates Cyclosporiasis Parasite Outbreak Linked to Severe Diarrhea in US.
Clinical Guidance and Symptoms
Cyclosporiasis is typically transmitted through the consumption of food or water contaminated with feces, with fresh produce serving as a primary carrier. The peak season for the illness is May 1 through August 31. A significant challenge for epidemiologists is the incubation period, which ranges from two days to two weeks between exposure and the appearance of symptoms.
The primary symptom of the infection is watery diarrhea, sometimes accompanied by nausea, loss of appetite, vomiting, or low-grade fever. Dr. Moore advises that clinicians should raise their index of suspicion for patients whose diarrhea persists for more than three days, given the current outbreak.
Treatment and Risk Management
For the majority of patients, the illness is self-limiting. Standard medical guidance focuses on hydration and the consumption of simple foods. Dr. Paul G. Auwaerter of the Johns Hopkins School of Medicine noted that testing may not be required for all patients, as many diagnostic panels are expensive and may not be covered by insurance.
However, a lower threshold for testing is recommended for individuals at higher risk of complications, such as the frail elderly or immunocompromised persons. In such cases, clinicians may consider antimicrobial therapy even in the absence of a confirmed diagnosis, depending on the patient’s specific health status and whether they show signs of improvement.
Health officials emphasize that there is currently no specific food item that the public is advised to avoid. The CDC continues to collaborate with state health departments to monitor the evolving situation.
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