U.S. sees sharp rise in cyclospora infections across several states
Health officials report hundreds of cyclospora cases in Michigan, Ohio and New York, prompting investigations into food and water sources as the parasite spreads during warm months.
Health departments in Michigan, Ohio and New York have reported unusually high numbers of cyclospora infections this summer. Michigan, which normally records about 50 cases a year, logged 681 cases since June 22, while Ohio identified 177 cases, 171 of them after June 20, and New York reported 112 cases outside New York City, 107 of which were confirmed after May 1. Officials are working to determine whether a common source is responsible for the spikes.
Cyclospora cayetanensis, the parasite that causes cyclosporiasis, is transmitted through contaminated food or water, often via raw produce such as berries and herbs, or through recreational water sources. Because the parasite undergoes sexual reproduction, its DNA changes rapidly, making molecular tracking methods used for bacteria ineffective. As a result, epidemiologists rely on detailed interviews and, in some cases, analysis of grocery receipts to trace exposures.
"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?’" said Dr. Max Teplitski, chief science officer for the International Fresh Produce Association.
Symptoms typically include watery diarrhea occurring more than three times daily, abdominal cramping and bloating, and may persist for up to six weeks in otherwise healthy individuals. Diagnosis requires a specific stool test that stains the parasite’s oocysts for microscopic identification, often needing multiple samples.
"It can be easily missed if you don’t do the right test," noted Dr. Rebecca Schein, an infectious disease specialist at Michigan State University.
Treatment consists of a seven- to ten-day course of trimethoprim-sulfamethoxazole. Health officials advise anyone with prolonged diarrhea, especially in areas with known outbreaks, to seek testing and treatment.
Recent research on washing methods for berries showed that rinsing with a vinegar-water solution removed more cyclospora oocysts than plain water, though some parasites remained, underscoring the importance of thorough produce cleaning.