Health departments in several U. S.
states are investigating a sharp increase in cyclosporiasis, a severe gastrointestinal illness caused by the Cyclospora cayetanensis parasite.
Unusual spikes have been recorded since May and June, prompting epidemiologists to search for common contamination sources.
Michigan health officials reported 681 cases since June 22, a substantial jump from the state's typical annual tally of around 50.
Ohio has registered 177 cases this year, with 171 occurring in June, while New York state has logged 112 cases outside New York City, 107 since May 1.
Tracing the parasite's origin is challenging due to its unique reproductive nature. The organism's complex genetic structure prevents standard DNA fingerprinting used for bacteria like E.
coli or Salmonella.
"Cyclospora is a weird one," said Dr. Max Teplitski, chief science officer for the International Fresh Produce Association and former head of the Division of Food Safety at the US Department of Agriculture.
He explained that the parasites undergo sexual reproduction inside human intestines, shuffling their genetic code and making their family tree nearly impossible to follow through molecular testing.
Epidemiologists must rely heavily on detailed patient interviews and purchase receipts. "We certainly hope that they go back and they ask their patients, 'What about recreational activities?
What about other types of exposure to well water?'" Teplitski said.
He added that water sources like lakes, well water, and water parks should be evaluated alongside raw produce.
Historical data since the mid-1990s links U. S.
outbreaks to fresh produce that is difficult to wash, such as raspberries, basil, cilantro, and salad mixes.
The parasite spreads through human feces, and its eggs must mature outside the body before becoming infectious.
The illness presents with prolonged symptoms distinct from bacterial food poisoning. "It's just more very watery diarrhea.
More than three times a day and then feeling kind of bloated, full, uncomfortable," said Dr. Rebecca Schein, an infectious disease expert at Michigan State University Health Sciences.
She described the sensation as "sort of like you just ate Thanksgiving dinner, but every day."
Investigations remain ongoing across the affected states to pinpoint the specific food or water sources responsible for the current outbreaks.
