Michigan cyclosporiasis outbreak tops 6,500 cases, state health officials say

The number of cyclosporiasis cases in Michigan continues to grow in the hundreds each day as health officials continue to track a parasite that can cause diarrhea and nausea after contaminated food is eaten.  

The Michigan Department of Health and Human Services says there are 6,571 cases in the state as of July 21, up 423 cases from the 6,148 reported on July 20. The Michigan patients included a woman who said she felt ill for several days after being affected. 

As of July 16, 102 people had received hospital treatment, more than double the 44 hospitalizations reported the previous week.  

Michigan health officials report the case numbers on Mondays through Fridays. The hospital reports are updated once a week on Thursdays.  

Impact in Michigan  

The cyclosporiasis outbreak, which Michigan officials said could be the largest in U.S. history, came to the attention of state and local health officials in late June. 

The outbreak was identified first by local officials in Monroe County and has since spread to 55 Michigan counties. Wayne, Ingham, Oakland, Monroe and Washtenaw are among the hardest-hit counties.

Michigan typically sees around 50 cases of cyclosporiasis per year, according to MDHHS. 

The CDC said it is also investigating reports of cyclosporiasis nationwide "that are unrelated to this outbreak." 

What's causing the outbreak?  

Michigan officials said July 13 that testing pointed to lettuce or salad greens as a potential source, though other foods hadn't been ruled out.

Efforts then focused on determining which supplier was involved  

The Food and Drug Administration said on Sunday that a sample of lettuce from Taylor Farms that had tested positive for cyclospora was a false positive. That leaves the investigation officially still open.  

Symptoms of the ailment  

Cyclosporiasis is caused by the parasite Cyclospora cayetanensis and spreads when infected feces contaminate food or water.   

Symptoms typically begin about a week after infection and include frequent watery diarrhea, loss of appetite, bloating, nausea and fatigue, lasting from two days to two weeks or longer.  

"Without treatment, illness can last for weeks and may come and go," Wayne County health officials said.   

The above video originally aired on July 20, 2026.