US sees rise in cyclosporiasis cases linked to contaminated produce

Health authorities have noted a surge in cyclosporiasis cases across Michigan and several other states. The illness, caused by the parasite Cyclospora, is typically spread through raw produce or water contaminated with human feces and peaks during the summer months of May to August.

The Centers for Disease Control and Prevention (CDC) says the most common symptom is watery diarrhea, often described as frequent and sometimes "explosive" bowel movements, which may resolve and then recur. Additional symptoms can include abdominal cramps, nausea, fatigue, loss of appetite, low-grade fever and vomiting, with illness lasting from a few days to over a month. The incubation period averages about a week, ranging from two days to two weeks, and person-to-person transmission is rare.

While cyclosporiasis is rarely life-threatening and most healthy individuals recover without treatment, those with weakened immune systems are at higher risk and may require antibiotic therapy. Past US outbreaks have been linked to contaminated irrigation water and raw foods such as berries, lettuce, spinach, basil, cilantro and other herbs. Notable incidents include a 2022 Florida outbreak tied to lettuce in packaged salad kits and larger outbreaks in 1996 and 2019 involving raspberries and basil, respectively.

Officials advise consumers to wash fresh produce thoroughly, though washing may not remove all parasites. They recommend purchasing whole heads of lettuce rather than pre-washed bagged varieties, discarding the outer leaves, and rinsing the remaining leaves under running water. Cooking produce when possible can also kill the pathogen.