Diarrhea-Causing Parasite Cases Surpass 1,000

Associated Press reported the largest parasitic infection outbreak in Michigan history and one of the nation’s largest in years is currently unfolding. In Michigan, 1,251 cases of cyclosporiasis, a parasitic infection that can cause weeks of watery diarrhea, have been reported, according to Michigan Department of Health and Human Services (MDHHS). As of July 9, 44 cases involved hospitalizations.

Typically, Michigan only identifies around 50 cyclosporiasis cases per year, MDHHS said. As cyclosporiasis cases continue to rise, the largest increase is occurring in Southeast Michigan, MDHHS reported. As of July 4, no specific produce grower/supplier, or specific produce type has been identified as the source of the outbreak.

Meanwhile, 28 other states have similar ongoing illnesses, including Ohio, where people just across the Michigan border are also becoming sick, AP reported. As of July 2, Ohio Department of Health reported 177 cyclosporiasis cases in the state in 2026, with 28 Ohioans hospitalized. 

Cyclosporiasis is caused by infection from the parasite Cyclospora cayatenensis, which is commonly found in developing countries and spread by food or water contaminated with feces. In recent years, outbreaks have occurred in the U.S. because of eating contaminated fresh produce, especially during the summer months. Cyclosporiasis is not known to spread from person to person. Symptoms occur two to 14 days after exposure and may include: 

• Frequent watery diarrhea. 
• Loss of appetite and weight. 
• Abdominal cramps and bloating. 
• Nausea (vomiting is less common). 
• Low-grade fever. 

Individuals experiencing sudden gastrointestinal illness are encouraged to seek evaluation by a health care provider. Symptoms of cyclosporiasis can be significantly improved with antibiotic treatment. If untreated, the illness may last for a few days to a month or longer. Providers are urged to consider cyclosporiasis among patients presenting with acute gastrointestinal illness in southeast Michigan. 

The following foods have been specifically linked to previous Cyclospora outbreaks in the United States and Canada:

• Bagged salad mixes and kits (precut lettuce blends with romaine, iceberg, red cabbage, carrots)
• Fresh cilantro (coriander leaves)
• Fresh basil
• Raspberries
• Snow peas
• Green onions (scallions)

To help avoid any illness from cyclospora or other harmful bacteria or organisms, MDARD also recommends the following: 

• Wash all fruits and vegetables thoroughly under running water before eating, cutting or cooking. 
• Scrub firm fruits and vegetables, such as melons and cucumbers, with a clean produce brush. 
• Cut away any damaged or bruised areas on fruits and vegetables before preparing and eating. 
• Refrigerate cut, peeled, or cooked fruits and vegetables as soon as possible.