Increase in Cyclosporiasis Cases Across U.S. States
Over a dozen U.S. states have reported a rise in cyclosporiasis cases, a parasitic illness known for causing severe diarrhea. Michigan is notably affected with over 1,500 cases and 44 hospitalizations as of July 9, data from the state’s Health and Human Services (HHS) department shows. Normally, Michigan records around 50 cases per year.
Michigan’s HHS stated that they haven’t identified the outbreak’s source yet. The illness is spreading to other states with 177 cases in Ohio, 141 in Illinois, 120 in New York, 110 in North Carolina, and 48 in Texas. This increase has caught national attention as health officials work to determine if it’s a severe outbreak or a seasonal pattern.
From May 1 to June 16, the Centers for Disease Control and Prevention (CDC) identified 145 domestically acquired cases across 17 states. It’s possible the outbreak is more extensive than current federal data suggests due to a lag in national reporting compared to state figures.
It seems that reporting is not consistent and may be less complete than it has been in earlier years at a similar point in the evolution of the cyclospora season. There is little or no information about possible clustering of cases and possible point sources of common exposure.
These observations are from David Relman, a professor at Stanford Medicine, who attributes the lack of information to reduced surveillance capabilities. Previous CDC efforts, cut back in 2025, included monitoring foodborne illnesses like cyclospora.
Contacting the CDC and the FDA for comments has so far not led to a response.
Unusual Increase this Year?
Keith Schneider from the University of Florida confirms this is a significant increase. Although historical data on cyclospora outbreaks is limited, in 2022 Florida had 513 cases traced to lettuce. Previous high counts were in 2018 and 2019 with over 3,000 and 4,000 cases respectively.
Halfway through 2026, cases have already surpassed 1,000. Such infections usually rise from May to August with fresh summer produce consumption spiking. Jennifer Acuff from the University of Arkansas notes, “We’ve had bigger outbreaks in the past, but this one is growing pretty large at a faster rate than I like to see.”
Sources of Cyclospora
Contaminated fresh produce, often exposed to tainted water or human waste, is the common infection source. Lee-Ann Jaykus from NC State University explains that cyclospora is associated with fresh vegetables, herbs, and certain fruits, mainly berries. Larger outbreaks are tricky as they often involve multi-component foods like salad mixes, complicating contamination source identification.
The investigation’s difficulties are amplified since symptoms appear a week post-exposure, making it tough for individuals to remember their meal history. Unverified claims on social media suggest some Taco Bell locations have pulled certain ingredients, such as lettuce, though the company hasn’t confirmed this.
Relman emphasizes the issue of not having a clear source yet. “This year we seem to understand even less than usual at this point about how people are getting infected and how many different sources are involved,” he stated.
Prevention Measures
Cyclosporiasis results from the Cyclospora cayetanensis parasite, typically from contaminated food or water. To prevent infection, avoid such items. Although washing produce doesn’t eliminate the parasite, it may lower ingestion risks, advises Jennifer Acuff. Symptoms, appearing about a week after infection, include diarrhea, cramps, bloating, and fatigue. Rarely fatal, the illness can last weeks, risking immunity-compromised individuals more.
For complete safety, avoiding fresh produce is recommended if you are immunocompromised. Relman points out washing’s limits as Cyclospora is sticky; clean produce and effective farming practices are vital. “A safe food supply is not something that simply happens through prayer and hope. It takes sustained resources, skill, and commitment,” he remarked.
Contact Newsweek editors Tobias Meyjes and Anthony Murray for story details.