Nearly 1,000 diagnosed in Michigan outbreak of diarrhea-causing parasite

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Nearly 1,000 Michiganders have been diagnosed with cyclospora, a parasitic infection capable of causing weeks of watery diarrhea, becoming one of the largest outbreaks of the infection in the state’s and the country’s history.

The Michigan Department of Health and Human Services (MDHHS) on Wednesday said there have been 992 confirmed cases with 40 hospitalizations. The department first reported last week that 170 cases were confirmed since late June. No deaths have been confirmed.

“The source of the outbreak has not been identified, and MDHHS continues to work with local health departments and partners to investigate cases and provide updates as more information becomes available,” the department stated on its website.

People fall ill with the infection after a microscopic, spherical parasite enters the intestines and causes watery diarrhea “with frequent and sometimes explosive bowel movements,” according to the Centers for Disease Control and Prevention (CDC). The illness can last several weeks or months if not treated with antibiotics and is usually not life-threatening.

Cyclospora spreads after people eat food or drink water contaminated with feces, the CDC states. It can take between two days and two weeks for a person to become sick, and person-to-person infection is unlikely. The parasites are typically linked to various types of fresh produce.

University of Minnesota foodborne illness researcher Melanie Firestone told The Associated Press that “there is a lot of underreporting when it comes to” cyclospora, as not all tests to check for types of food poisoning are designed to detect cyclospora.

Between May 1 and June 16, before cases in Michigan were first reported, only 145 cases of cyclospora had been reported, according to the CDC. The agency added that there is no evidence of a single outbreak linking all cases of cyclospora across the country. The typical outbreak season started on May 1.

The CDC has documented cyclospora outbreaks since 1997, when an outbreak connected to Guatemalan raspberries caused more than 1,000 Americans and Canadians to fall ill. The National Institutes of Health reported that an outbreak connected to Mexican basil in 2019 caused more than 2,400 cases.

MDHHS urges Michigan residents purchasing heads of lettuce to throw out the outer two or three layers of leaves and wash the inner leaves under running water.

The department also advises people to thoroughly wash cilantro and basil under running water to separate the leaves, and trim the root ends and remove the outer layers of green onions before also running them under water. Similarly, the department suggests washing snow peas under running water and rubbing their surface.

Raspberries can be the hardest to clean, as the parasite can hide in the bumpy surface, with the MDHHS stating that they are safest when cooked as part of pies or jams. Frozen raspberries can be an alternative, but freezing raspberries does not guarantee that the parasites have been eliminated.

All of these foods are safest when cooked, health officials said.

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