Federal health officials have confirmed 145 cases of cyclosporiasis across 17 states as of mid-June 2026, with no single common source yet identified. The Centers for Disease Control and Prevention, alongside the Food and Drug Administration and state health authorities, is actively investigating several multi-state clusters of the microscopic Cyclospora parasite — and the outbreak season has months left to run.
What Cyclospora Is and Why Summer Matters
Cyclospora is a microscopic parasite that causes cyclosporiasis, an intestinal illness whose defining symptom is watery, frequently "explosive" diarrhea that can persist for weeks or even months without treatment. Patients also report severe abdominal cramping, bloating, nausea, fatigue, and significant weight loss. The official outbreak season runs from May 1 through August 31, a window when warmer temperatures historically coincide with a surge in infections, according to the CDC.
While the infection sometimes resolves without intervention, it frequently requires antibiotics. Of the 145 confirmed cases, 20 patients have required hospitalization. No deaths have been reported.
Where Cases Are Concentrated
New York has borne the heaviest caseload, with between 31 and 80 confirmed infections. Texas and Illinois follow, each reporting between 11 and 30 cases. Taken together, cases have emerged as far apart as Texas and Alaska — a geographic breadth that complicates the search for a common exposure source.
Patients range in age from 5 to 86 years old, with a median age of 42. Women account for 61 percent of reported cases.
A Fragmented Outbreak, Not a Single Source
The CDC has been explicit about the limits of what investigators currently know. "There is currently no evidence of a single, multistate Cyclospora outbreak linking all cases," the agency stated in its surveillance report. That finding is significant: officials are contending with multiple, potentially distinct clusters rather than one contaminated food supply or water system.
With the outbreak season extending through August 31, case counts are likely to rise before investigators can identify a source. The CDC advises anyone experiencing cyclosporiasis symptoms — particularly prolonged diarrhea — to contact a healthcare provider for testing and treatment.