Between May 1 and July 1, 18 cases of cyclosporiasis were reported in Massachusetts. This uptick contributes to a broader surge of the diarrhea-causing parasite Cyclospora, which is spreading across most of the midwestern United States. State-level data indicates that 2026 is currently the nation’s worst year for reported cases. While an outbreak exceeding 3,000 cases has been reported in Michigan and Ohio, experts suggest the situation in Massachusetts remains consistent with typical seasonal patterns.
Dr. Zoe Weiss assesses the Massachusetts cyclospora trend
Dr. Zoe Weiss, an infectious disease doctor at Tufts Medical Center, noted that the 18 cases in Massachusetts are in line with the usual number of cases seen during the spring and summer months. “It’s probable that we won’t have as many cases in Massachusetts as we will in areas like Michigan, where they’re already seeing thousands of cases,” Weiss said.
Understanding the Parasite and Transmission
Cyclospora is a heat-loving parasite that infects the bowels and spreads through the fecal-oral route. Anyone can contract cyclosporiasis by consuming fresh, uncooked produce contaminated with the parasite. Past infections have been linked to fruits or vegetables exposed to feces-contaminated irrigation water. Emily Landon, UChicago Medicine’s executive medical director of infection prevention and control, explained the mechanism of contamination: “Things that grow in fields can get contaminated by poop from other animals, and sometimes produce can get indirectly contaminated if contaminated water is used to wash it off before it’s ready to be sent off. Imagine if you have a few things that are contaminated, and then they all get dunked into water together.”
Emily Landon identifies risks in produce contamination
Produce items specifically linked to cases include raspberries, bagged lettuce, cilantro, scallions, snow peas, and fresh basil. Landon noted that for foods like broccoli, berries, leafy greens, and fruits with crevices, it is especially difficult to fully wash off the parasite.
Clinical Context and Reporting
While cyclosporiasis is not fatal, symptoms include bouts of “explosive diarrhea” that can last from days to several weeks. Other symptoms include loss of appetite, bloating, increased gas, stomach cramps, nausea, and sometimes vomiting. Diagnosing the infection can be difficult, as symptoms usually take weeks to appear, making it challenging for patients to recall their dietary history.
The Illinois Department of Public Health monitors domestic cases
In Illinois, the Department of Public Health reported 216 cases as of Tuesday. Of those, 96 individuals reported traveling outside of the U.S., while 95 acquired the illness domestically. A spokesperson for the Illinois Department of Public Health stated, “At this point, no single source or cause of this increase has been identified, and there is no evidence of a large outbreak accounting for all or most of these cases.” The department continues to work with the Centers for Disease Control and Prevention to monitor trends.
Guidance for Consumers
Regarding risk management, Landon suggested that individuals with serious immune problems or gut health issues should be particularly careful about the fresh produce they consume, whether at home or in restaurants. She recommends avoiding fast-food chains and instead choosing to eat at home or at smaller, local restaurants, which she believes carry a lower risk due to the lower volume of food handled. As the investigation into the outbreaks continues, some companies, such as Taco Bell, have announced they would begin pulling certain ingredients from their menus as a precaution.
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