US sees rise in cyclosporiasis cases linked to contaminated produce

Health authorities say a seasonal surge in cyclosporiasis, an intestinal infection caused by the parasite Cyclospora, is affecting several U.S. states, including Michigan. The parasite is typically transmitted through raw fruits, vegetables or water contaminated with human feces, and outbreaks most often occur between May and August.

The Centers for Disease Control and Prevention notes that the illness commonly produces watery, sometimes "explosive" diarrhea, which may pause and then recur, along with abdominal cramps, nausea, fatigue, loss of appetite, low-grade fever and vomiting. Symptoms appear about a week after exposure, ranging from two days to two weeks, and can last from several days to more than a month. While most healthy individuals recover without treatment, those with weakened immune systems are at higher risk and may require antibiotics.

Past U.S. outbreaks have been traced to contaminated irrigation water and produce, such as the 2022 Florida cases linked to lettuce in packaged salad kits and earlier incidents involving raspberries and basil. Outbreaks exceeding 1,000 cases are rare, with notable examples in 1996 and 2019.

Officials advise consumers to wash fresh produce thoroughly, though washing may not remove all parasites, especially from items with crevices like berries, lettuce, spinach, cilantro and basil. They recommend buying whole heads of lettuce rather than pre-washed bags, discarding the outer leaves, and rinsing the remainder under running water. Cooking produce when possible can also kill the pathogen.