The CDC is urgently trying to find the source of the outbreak which has sickened hundreds of people across the U.S. since the beginning of May.
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A parasitic infection has emerged, affecting hundreds in 17 states, leading the U.S. Centers for Disease Control and Prevention (CDC) to launch a nationwide investigation. This rapidly spreading outbreak has resulted in at least 145 cases, with additional reports from various states. The CDC is urgently seeking the outbreak’s source, suspected to be fresh produce contaminated with human feces.
The CDC’s latest update on July 2nd reveals that the illnesses happened between May 1st and June 16th. While there have been no fatalities, 20 people have been hospitalized. The CDC is collaborating with state health departments and the U.S. Food and Drug Administration (FDA) to identify the infection’s source. They are exploring multiple potential contamination sources, but have not yet identified any specific cause.
The infection, known as cyclosporiasis, is caused by the Cyclospora cayetanensis parasite, which infiltrates the gut when contaminated food or water is consumed. Symptoms include severe watery diarrhea, loss of appetite, bloating, nausea, stomach cramps, fever, weight loss, and muscle pain. The parasite is not directly transmissible from person to person.
Symptoms typically manifest about a week after exposure, but may appear as soon as 2 days or as late as 2 weeks post-ingestion. Although many healthy individuals recover without treatment over several weeks, the anti-parasitic drug trimethoprim-sulfamethoxazole can effectively treat most patients.
In the U.S., cyclosporiasis is frequently linked to fresh produce contaminated by feces, rather than through meat or person-to-person contact. Past outbreaks have been connected to both imported and domestically grown leafy greens, basil, cilantro, raspberries, and packaged salad mixes, often consumed raw.
The CDC cautions that while washing fruits and vegetables may reduce the risk of infection by removing some parasites, Cyclospora can cling to produce surfaces and may hide in crevices, making complete removal by washing challenging. Cooking is the only sure method to eliminate the parasite.
The ongoing national investigation coincides with an unusual surge in cases in Michigan. State health officials have reported over 170 infections across at least seven counties, exceeding three times the state’s annual average of about 50 cases. It remains unclear whether Michigan’s cases are part of the broader CDC investigation or stem from a different outbreak with another source.
Though cyclosporiasis is relatively rare in the U.S. compared to bacterial or viral food poisoning, significant foodborne outbreaks have occurred over the past decade. In 2018, 761 laboratory-confirmed illnesses across several states were linked to contaminated produce, including pre-packaged vegetable trays and restaurant salads sold at McDonald’s. In 2020, another multistate outbreak was traced to bagged salad mixes.
Until the source of this year’s outbreak is identified, the CDC advises healthcare providers to consider cyclosporiasis in patients with persistent diarrhea and urges individuals to seek medical attention if symptoms occur after consuming fresh produce.
