Outbreak of diarrhea from parasite expands to more states as US cases soar beyond last year’s level

By Deidre McPhillips, CNN

(CNN) — There have been 1,645 confirmed cases of cyclosporiasis acquired in the United States since May 1, and more than 5,100 additional cases are being investigated, the US Centers for Disease Control and Prevention said on Tuesday.

A growing outbreak in Michigan and Ohio has also been linked to cases in West Virginia and Kentucky, the agency said. People with cyclosporiasis may experience symptoms, including watery diarrhea, cramping and bloating, for weeks.

Since May 1, cases have been identified in 34 states. Cyclospora activity tends to increase during the spring and summer, but the number of confirmed cases since May 1 is already more than six times higher than it was by this time last year, according to a health alert sent by the CDC. If all possible cases being investigated are included, this year’s total is 27 times higher than last year’s total at this time.

“This is much, much higher than what we’ve seen last year or the year before,” said Dr. Gwen Biggerstaff, deputy director of CDC’s Division of Foodborne, Waterborne, and Environmental Diseases, calling it “a very big shift” from previous seasons.

About 1 in every 11 cases has been hospitalized, according to data available to the CDC. No deaths have been reported. At least 34 states have reported cases.

An additional investigation notice published by the CDC on Tuesday notes that at least 400 cases across at least four states — Michigan, Ohio, West Virginia, and Kentucky — “appear to be epidemiologically linked, suggesting that there could be a common source of these infections.”

The Michigan state health department has reported more than 3,300 cases of cyclospora “during the outbreak investigation.” Michigan has said current results suggest lettuce or salad greens may be a potential source for the outbreak, but it hasn’t ruled anything out.

According to a 2023 report from the US Department of Agriculture’s Food Safety Inspection Service, the largest cyclospora outbreak in the US on record led to about 1,500 cases and involved raspberries.

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