The Centers for Disease Control and Prevention is tracking a surge in cases of a microscopic parasite that causes prolonged gastrointestinal illness.
As of mid-June 2026, the CDC has reported 145 cases of cyclosporiasis across 17 states, with all infections linked to illnesses acquired in the U.S.
The culprit behind the outbreak is Cyclospora, a microscopic parasite known to cause cyclosporiasis, a condition characterized by watery, often "explosive" diarrhea that can last for weeks or even months if left untreated.
The hallmark symptoms of the infection include severe abdominal cramping, bloating, nausea, fatigue, and significant weight loss, according to the CDC.
The official outbreak season for the parasite runs from May 1 through August 31, a period when warmer temperatures historically coincide with a spike in infections, the CDC notes.
Cases have been reported in states ranging from Texas to Alaska, with New York being the hardest hit so far, reporting between 31 and 80 cases, followed by Texas and Illinois, which have between 11 and 30 cases.
Out of the 145 confirmed cases, 20 patients have required hospitalization, and no deaths have been reported, according to the CDC.
The patients affected range from 5 to 86 years old, with a median age of 42, and women make up 61% of cases, according to the data.
The CDC, along with the Food and Drug Administration and state health officials, is actively investigating several multi-state clusters, but a cause behind the spread has yet to be identified.
The CDC notes that there is currently no evidence of a single, multistate Cyclospora outbreak linking all cases, and advises anyone experiencing symptoms of cyclosporiasis to contact a healthcare provider for testing and treatment.
