Update 07/20/2026: This article has been updated to reflect that the Food and Drug Administration has said the Taylor Farms cyclospora test was a false positive and is not the origin of the outbreak.
As Cyclospora cayetanensis, a diarrhea-causing parasite, infects thousands in the Midwest and on the East Coast, California has yet to see any outbreaks. However, Berkeley residents can still take precautions, especially by washing and cooking produce instead of eating it raw.
Since May 1, U.S. Centers for Disease Control and Prevention data show 10 or fewer reported cases of the parasite in California, compared to hundreds of cases in Michigan and New York. The California Department of Public Health said in a statement Tuesday that California has only seen 41 provisional cases from January to June of this year, down from 80 over the same period in 2025.
Cyclosporiasis, the disease caused by cyclospora, induces watery diarrhea, as well as symptoms such as appetite and weight loss, cramps, bloating, nausea and fatigue. The parasite can be contagious via feces of infected people, and past cyclosporiasis outbreaks have been traced to contaminated fresh produce. Individuals carrying the parasite are unlikely to directly infect other people.
“So it is ingested orally, and it’s able to pass the acidic area of the stomach, and it’s then able to establish itself in our intestine,” said Filipa Rijo-Ferreira, a UC Berkeley School of Public Health assistant professor who studies parasitic diseases. She explained that disturbances in the intestine cause cyclosporiasis’ signature symptom: “very prolonged and explosive diarrhea.”
Investigators previously linked the outbreak in Michigan and three other states to potentially contaminated iceberg lettuce from fresh produce supplier Taylor Farms, according to an earlier report by The Washington Post. However, now the Food and Drug Administration has said that the Taylor Farms sample that tested positive for cyclospora was a false positive.
Despite California having fewer cases so far, state public health officials say cases may increase as the summer travel season brings people from impacted Midwest states to California. Rijo-Ferreira thinks the centralized food distribution system in the U.S. means there is a risk of contaminated products reaching California. She added that immunocompromised individuals should be especially careful.
“Instead of eating as many raw vegetables, if we were to cook, that is the simplest way that we have in our hands to avoid (cyclosporiasis),” Rijo-Ferreira said. “Or just having fruits that you peel, instead of actually eating things directly raw.”
In addition, state and federal public health agencies are emphasizing the importance of proper handwashing, washing produce, preventing cross-contamination between cutting boards, refrigerating cut or cooked vegetables as soon as possible and avoiding food or water that may be contaminated with feces.
Correction 07/20/2026: A previous version of this article misspelled Filipa Rijo-Ferreira.
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