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July 2, 2026, 9:30 a.m. ET
The Michigan Department of Health and Human Services is tracking a “large and growing” outbreak of a parasitic infection called cyclosporiasis, which causes abdominal pain, bloating and watery, explosive diarrhea, across a widening part of the state.
More than 225 cases were identified in 21 Michigan counties and the city of Detroit between June 22 and July 1, said Lynn Sutfin, a spokesperson for the Michigan Department of Health and Human Services. That number is expected to grow, state health officials said.
Sutfin provided the Detroit Free Press with this county-by-county case tally of cases as of 4:30 p.m. July 1. They include:
Monroe: 92 cases
Lenawee: 36 cases
Washtenaw: 28 cases
Wayne (not including the city of Detroit): 17 cases
Jackson: 11 cases
Shiawassee: 9 cases
Ingham: 6 cases
Oakland: 5 cases
City of Detroit: 3 cases
Livingston: 3 cases
Sanilac: 3 cases
Hillsdale: 2 cases
Lapeer: 2 cases
Eaton: 1 case
Genesee: 1 case
Gratiot: 1 case
Houghton: 1 case
Leelanau: 1 case
Manistee: 1 case
Ottawa: 1 case
Saginaw: 1 case
What is cyclosporiasis?
It’s an illness caused by a microscopic parasite called cyclospora cayatenensis, which is common in tropical and subtropical parts of the world.
Fresh produce imported to the U.S. from these regions can be contaminated with the pathogen. People can get sick after eating food or drinking beverages that have been tainted with it or after traveling to parts of the world where cyclospora cayatenensis is endemic.
Cyclosporiasis is not known to spread from person to person.
What is the source of this outbreak?
It remains unclear. An investigation involving MDHHS, the state department of agriculture, and the U.S. Centers for Disease Control and Prevention is underway.
MDHHS issued a health alert June 30 to physicians and other medical providers statewide, asking that they test stool samples from patients who have diarrhea and other symptoms associated with cyclosporiasis. They are asked to report positive results to their local health departments within 24 hours.
Anyone who recently has been diagnosed with cyclosporiasis also is encouraged to report it by calling their local health department.
What are the symptoms of cyclosporiasis?
According to MDHHS, symptoms of cyclosporiasis typically begin two to 14 days after exposure and may include:
Diarrhea that is watery and can be explosive.
Abdominal cramps and bloating.
Loss of appetite.
Weight loss.
Nausea.
Low-grade fever.
Vomiting has been reported as a symptom, although it is less common.
Anyone experiencing sudden gastrointestinal illness should be evaluated by a health care provider, state health officials say. Cyclosporiasis infections can be treated with antibiotics. However, if an infection remains untreated, the illness could last for days to a month or longer.
Could the outbreak extend beyond state lines?
As Michigan public health authorities try to identify the scope of the outbreak, over the border in Ohio, there’s a similar search for answers.
The Toledo-Lucas County Health Department is investigating 65 cases of cyclosporiasis identified between June 25 and 7 a.m. July 1, said Sarah Velliquette, a spokesperson for the department.
Health officials in northwest Ohio are working with “partners across the region as part of this ongoing investigation by sharing information and reviewing potential commonalities,” Velliquette said. “This includes health departments in [southeastern] Michigan, the Ohio Department of Health, the Ohio Department of Agriculture, regional health departments in [northwest] Ohio, and area hospitals.
“As of this moment, case investigation work is underway to identify the possible source of contamination.”
The CDC, however, did not acknowledge any links between the cases in Ohio and those in Michigan. In an emailed statement sent to the Detroit Free Press July 1 from CDC Press Officer Lisa George, the agency said:
“CDC has no evidence of a single, multistate Cyclospora outbreak linking cases happening right now and being reported in [the] press. The data currently found on CDC’s website is a surveillance count of cases across the United States of people with cyclosporiasis. This number includes clusters of cases currently under investigation by the FDA [U.S. Food and Drug Association] and cases that have not been linked to a common source.
“The cases that are being reported are not linked together.”
As of July 1, the CDC surveillance website, however, listed only 145 cases nationally that were identified through June 16. Michigan’s first case associated with the latest outbreak wasn’t reported to health officials until June 22 and the 65 cases in Lucas County, Ohio, were reported after June 25.
How to protect yourself from illness
Michiganders are urged to take precautions to protect themselves from a cyclosporiasis infection.
Previous outbreaks in the U.S. have often been linked to imported fresh produce such as basil, cilantro, Mesclun lettuce, raspberries and snow peas, according to the CDC. It also has been identified in people who traveled to cyclospora-endemic areas.
In a statement issued July 1, Jennifer Bonsky, the director of the Human Food Division at MDARD, said the agency is “committed to ensuring food safety across the state and is working in partnership with local health departments to identify the source of the outbreak and keep consumers safe. In these moments, it becomes even more important to follow all of the essential food preparation guidelines, such as washing your hands before and after preparing food and washing produce before it is consumed.”
To avoid cyclosporiasis and illness caused by bacteria or other organisms, MDARD recommends:
Washing your hands with soap and water before and after handling or preparing raw fruits and vegetables.
Washing all fruits and vegetables thoroughly under running water before eating, cutting or cooking.
Fruits and vegetables that are labeled “prewashed” do not need to be washed again at home.
Scrubbing firm fruits and vegetables, such as melons and cucumbers, with a clean produce brush.
Cutting away any damaged or bruised areas on fruits and vegetables before preparing and eating.
Refrigerating cut, peeled or cooked fruits and vegetables as soon as possible (within two hours).
There have been restaurant-associated cases, too
It isn’t just the produce people buy at grocery stores, however, that have been traced to cases of cyclosporiasis.
In 2018, McDonald’s restaurants in Illinois and Iowa were identified as the source of an outbreak involving its salads. The restaurant chain stopped selling salads in 14 states after the CDC reported 61 people across seven states got sick, according to the U.S. Food and Drug Administration.
In 2019, the CDC reported multiple restaurant-associated cases across several states tied to fresh basil sold by Siga Logistics de LL de CV of Morelos, Mexico. And another cluster of cases occurred in 2023 among people who dined at a Mexican restaurant in Limestone County, Alabama. The CDC reported that contaminated cilantro was the likely source.
“Individuals concerned about sudden gastrointestinal illness should contact a health care provider,” Sutfin said. “Individuals experiencing diarrheal illness or vomiting are encouraged to hydrate, particularly during the high temperatures expected this week.”
Contact Kristen Shamus: [email protected]. Subscribe to the Detroit Free Press.
