Michigan, Ohio report sharp rise in parasitic infection cases

Michigan’s cyclosporiasis cases climbed to 572 by July 4, up from 170 four days earlier, while Ohio had 177 infections across 43 counties as of July 2, with most of its cases coming after June 20. The surge is still moving because cyclosporiasis can take days to weeks to show up after exposure, and the illness is tied to contaminated food or water rather than person-to-person spread.

Cyclosporiasis is caused by the microscopic parasite Cyclospora cayetanensis. Symptoms usually begin about one week after exposure, but they can appear as soon as two days or as late as two weeks or more. Untreated illness can last from a few days to more than a month, and symptoms may fade and then return. Frequent diarrhea can lead to dehydration, which can be more severe for younger people, older adults and patients with weakened immune systems.

On July 4, Michigan had not identified any specific produce grower, supplier or produce type. Earlier in the outbreak, more than 170 cases had been identified in Monroe, Lenawee, Washtenaw, Wayne, Livingston, Shiawassee and Jackson counties in the prior nine days. Southeast Michigan later saw the largest increase. Ohio health departments are using the CDC’s Cyclosporiasis National-Hypothesis-Generating Questionnaire in case follow-up.

Past U.S. and Canadian outbreaks have been linked to bagged salad mixes and kits, fresh cilantro, fresh basil, raspberries, snow peas, green onions and mesclun lettuce. The Centers for Disease Control and Prevention found no evidence of a single multistate Cyclospora outbreak linking all U.S. cases as of July 1, and 145 U.S.-acquired cases from 17 states had been identified from May 1 through June 16. The count included 20 hospitalizations and no deaths, with a median illness onset date of May 13. Michigan weekly counts are provisional and will continue to change as cases are investigated, confirmed or ruled out.