As Americans gear up for Fourth of July barbecues and picnics, a nasty parasite is quietly making its way through produce aisles and onto dinner plates. Cyclospora, the microscopic culprit behind a wave of explosive diarrhea cases, has infected hundreds across more than 17 states since May, according to the Centers for Disease Control and Prevention and state health data. Michigan is particularly hard hit, with a cluster of infections that has already tripled its total case count compared to last year.
Health officials are scrambling to find a common source, but so far, no single outbreak has been identified. The CDC says the cases appear to be part of a seasonal surge, though investigations are ongoing. “CDC has no evidence of a single, multistate Cyclospora outbreak linking cases happening right now,” the agency stated in early June. The numbers include clusters under FDA investigation and cases with no known link.
Cyclosporiasis is caused by the Cyclospora cayetanensis parasite, often found on fresh produce like basil, raspberries, and lettuce. Symptoms include watery, frequent, and sometimes explosive diarrhea, along with nausea, vomiting, and stomach cramps. The infection spreads through the fecal-oral route—meaning contaminated food, water, or surfaces tainted with infected stool particles.
As of June 16, 145 people contracted the infection within the U.S., with 20 hospitalized and no deaths. Ages ranged from 5 to 86, with a median of 42. The cyclosporiasis season runs from May through August, when warm weather helps the parasite thrive on fresh produce. But Michigan’s numbers tell a different story: more than 170 cases have been reported since June 22, a stark jump from last year’s statewide total of about 50.
People typically become sick about a week after exposure, though symptoms can appear in as little as two days or as late as two weeks. Antibiotics can treat the infection, but prolonged cases can last months and recur. Children, the elderly, and those with weakened immune systems are most at risk for severe illness.
To avoid the parasite, health officials recommend washing all fresh fruits and vegetables thoroughly, cooking produce when possible, and practicing good hand hygiene. Avoid eating raw produce that may have been contaminated, especially during the summer months. The CDC updates its surveillance dashboard monthly, so stay informed if you’re planning a holiday feast.
