More than 150 people in 7 Michigan counties sickened by parasite outbreak

More than 150 people in seven Michigan counties were sickened by cyclosporiasis since June 22, health officials said. The intestinal illness, caused by the parasite Cyclospora cayetanensis, is spread through food or water contaminated with feces and has been linked to outbreaks involving fresh produce, officials said.

The outbreak spans seven counties: Monroe, Lenawee, Washtenaw, Wayne, Livingston, Shiawassee, and Jackson, officials said. The Michigan Department of Health and Human Services (MDHHS) confirmed it is working with local health departments in the region to investigate the surge and identify a common exposure.

Monroe County health officials reported 67 of the more than 150 cyclosporiasis cases identified in southeast Michigan since June 22, according to a statement from the Monroe County Health Department.

Cyclosporiasis is caused by the intestinal parasite Cyclospora cayetanensis, which is transmitted through food or water contaminated with feces, health officials explained. The parasite is not known to spread from person to person. The recent cluster in southeastern Michigan represents a sudden and large increase in cases, prompting coordinated epidemiologic investigations by state and local authorities.

Symptoms of cyclosporiasis typically appear two to 12 days after exposure and include frequent watery diarrhea, loss of appetite, weight loss, stomach cramps, bloating, nausea, fatigue, and low-grade fever, according to the Monroe County Health Department and MDHHS. Officials noted that symptoms may seem to resolve and then return, and untreated infections can last for weeks. While the illness is not considered life-threatening, it can significantly affect quality of life. Health departments recommend that individuals experiencing gastrointestinal symptoms seek medical evaluation for testing and treatment with antibiotics, which can effectively clear the infection. Maintaining hydration is also advised, especially during periods of high temperatures.

The outbreak coincides with a broader national context. CDC-linked data cited by CBS Detroit show more than 140 cyclosporiasis cases reported across the United States between May 1 and June 16, 2026. These cases occurred in 31 states, including Michigan, suggesting widespread exposure to contaminated produce or water sources, officials said. Recent U.S. outbreaks of cyclosporiasis have been linked repeatedly to fresh produce, particularly leafy greens, herbs, and other raw fruits and vegetables consumed during summer months.

MDHHS and local health authorities have not yet identified a specific food or water source responsible for the Michigan outbreak. Monroe County officials are currently investigating the source of the local cluster and emphasize that all produce should be thoroughly washed before consumption, whether served in restaurants or prepared at home. They also advise consumers to scrub firm fruits and vegetables with a clean brush, cut away damaged or bruised areas, and refrigerate cut, peeled, or cooked produce within two hours to reduce microbial risks.

Health officials reiterated that the parasite is contracted through the fecal-oral route and stressed that person-to-person transmission is unlikely. They cautioned residents to avoid consuming food or water that may be contaminated with feces and urged vigilance in food handling practices amid the ongoing investigation.

The MDHHS and Monroe County Health Department continue to monitor the situation closely and coordinate efforts to identify potential common exposures. Officials encourage individuals experiencing symptoms consistent with cyclosporiasis to contact healthcare providers promptly for testing and treatment. The investigation remains ongoing as public health authorities work to determine the outbreak’s source and prevent further cases.