The infections are concentrated primarily in southeast Michigan counties including Wayne, Oakland, Washtenaw, Monroe, Lenawee, Shiawassee, Jackson, Ingham, and Livingston, according to state updates and local health reports. The department described the situation as a growing outbreak and emphasized that investigations are ongoing.

The Michigan Department of Health and Human Services (MDHHS) reported a rapid increase in cyclosporiasis cases, rising from 1,562 on July 10 to 2,640 by July 13, 2026, indicating a significant escalation in the outbreak over a short period.

Preliminary testing by MDHHS has identified lettuce and salad greens as a potential source of the outbreak, though officials have not yet confirmed any specific grower, supplier, or produce type linked to the cases. Dr. Natasha Bagdasarian, Michigan’s chief medical executive, stated that while no definite product has been identified, early information shows lettuce as a common item associated with the investigation. MDHHS also noted that other food items have not been ruled out and that the findings remain preliminary.

The department issued public guidance on July 4, 2026, to help prevent foodborne illness amid the outbreak. This included recommendations to buy whole heads of lettuce rather than prewashed bagged lettuce or salad mixes, discard the outer two to three layers of leaves, and wash inner leaves under running water. For leafy greens that can be cooked, MDHHS advised that cooking is the safest option, as heating food to 158 degrees Fahrenheit (70 degrees Celsius) or higher kills Cyclospora parasites. Consumers were also urged to wash all fresh produce thoroughly, even if it will be peeled later.

Cyclospora infection typically causes watery or severe diarrhea, stomach cramps, and nausea, according to local health reports linked to the outbreak. Treatment involves antibiotics, along with rest and adequate hydration, officials said. MDHHS urged those experiencing symptoms to contact their health care provider and local health department. The department also recommended handwashing with soap and water before and after handling food and sanitizing utensils, cutting boards, refrigerators, and produce display cases to reduce the risk of contamination.

The outbreak timeline shows a sharp increase in cases over recent weeks. On June 30, 2026, local reports indicated 572 cases, up from 170 earlier that week. By July 4, MDHHS had issued its initial public recommendations, and on July 5, the department confirmed that no specific grower or supplier had been identified. State bulletins on July 7 reported 784 cases clustered in multiple southeast Michigan counties, with numbers continuing to climb sharply through mid-July.

MDHHS highlighted that several foods have been linked to previous Cyclospora outbreaks in the U.S. and Canada, including bagged salad mixes and kits, fresh cilantro, fresh basil, raspberries, snow peas, and green onions. The department’s guidance specifically noted bagged salad mixes and kits as pre-cut lettuce blends associated with earlier outbreaks and identified lettuce and leafy greens as foods requiring special caution during the current investigation.

The department maintained an active investigation status as of the latest updates, with source identification still incomplete. Officials continue to monitor the outbreak and update the public through the MDHHS Cyclosporiasis Outbreak 2026 webpage. The department’s ongoing efforts include testing potential sources and coordinating with local health agencies to track new cases and provide updated guidance.

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.