Public health officials across several US states are monitoring a wave of cyclospora cases that has left more than 1,400 people diagnosed with the intestinal illness in Michigan and Ohio alone, with additional clusters reported in Pennsylvania and New Jersey. The parasite causes watery and sometimes explosive diarrhoea and, while rarely life-threatening, can produce prolonged illness — particularly in people with compromised immune systems.
The Centers for Disease Control and Prevention recorded 145 reported cases of cyclosporiasis nationally between May 1st and June 16th, including a cluster in Pennsylvania and New Jersey. Michigan’s state health department has reported more than 1,200 diagnoses as of July 9th. Ohio health officials have recorded 177 cases as of July 2nd. Pennsylvania has logged 28 cases in 2026, with 14 concentrated in the south-eastern part of the state. No deaths from the illness have been reported this year, and the CDC has said there is currently no evidence that the cases constitute a single coordinated multistate outbreak.
What Cyclospora Is and How People Get It
Cyclospora cayetanensis is a microscopic single-celled parasite — too small to see without a microscope — that causes intestinal illness when ingested. It is endemic in tropical and subtropical regions of the world but reaches the United States primarily through contaminated imported produce. Foodborne outbreaks in the US have historically been linked to basil, cilantro, raspberries, and snow peas. Cases tend to rise during spring and summer months, though they can occur at any time of year.
The time between infection and the onset of symptoms is approximately one week, according to the CDC.
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What the Symptoms Look Like
The defining symptom of cyclosporiasis is watery, and sometimes explosive, diarrhoea. Associated symptoms include bloating, stomach cramps, fatigue, increased gas, and loss of appetite. Less commonly, people experience body aches, a low-grade fever, and vomiting. Some people with healthy immune systems show no symptoms at all.
Left untreated, symptoms can last anywhere from a few days to more than a month. People with compromised immune systems are at risk of more severe or prolonged illness.
How It Is Diagnosed and Treated
Doctors diagnose cyclosporiasis using stool samples. The parasite is difficult to detect, and healthcare providers often require multiple samples before confirming a diagnosis. Once confirmed, some providers prescribe antibiotics. The CDC notes that most people with healthy immune systems will recover without any treatment.
How to Protect Yourself
The exact route by which the parasite enters food and water sources is not fully understood. Routine disinfection methods are unlikely to kill cyclospora in areas where it is endemic, the CDC warns. Standard food hygiene practices remain the most effective protection available.
The Pennsylvania Department of Health recommends washing hands with soap and water before and after handling raw fruit and vegetables, rinsing all produce — including herbs — under running water, scrubbing firm produce such as melons and cucumbers with a clean brush, cutting away any damaged areas before eating, and refrigerating cut, peeled, or cooked produce promptly. These steps, officials say, will significantly reduce the risk of ingesting the parasite.
If you or someone you know is experiencing prolonged diarrhoea or symptoms consistent with cyclosporiasis, consult a healthcare provider. If you are immunocompromised and develop gastrointestinal symptoms, seek medical attention promptly.
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