CDC investigates cyclosporiasis outbreak across 17 U.S. states

The CDC confirmed 145 cases of a parasitic stomach illness across 17 American states between May and mid-June 2026. The parasite, Cyclospora cayatenensis, causes frequent watery diarrhoea and can last more than a month without antibiotic treatment. Twenty people needed hospital care. Michigan saw the sharpest rise, recording over 170 cases in just nine days across seven counties, far above its usual annual total of around 50. New York had the highest confirmed case count of any single state. Investigators have not yet identified one shared food source, though most patients had not travelled abroad before falling ill, pointing to a domestic origin. Fresh produce such as lettuce, herbs, and berries commonly carries the parasite. It cannot pass directly from person to person.