A growing cyclospora outbreak has sickened more than 3,000 people in Michigan and Ohio, and investigators now say lettuce or salad greens may be part of the picture. Michigan health officials have not identified a specific grower, supplier, or food item, and other foods cannot be ruled out.
State officials said early information keeps pointing to lettuce as a product that repeatedly comes up during interviews. “Early information has shown lettuce as a common product that regularly comes up during the investigation,” Michigan’s chief medical executive, Dr. Natasha Bagdasarian, said in a statement Monday.
What the current case counts show
| Location | Reported Cases | Hospitalizations |
|---|---|---|
| Michigan | 2,640 | 44 |
| Ohio | 361 | At least 46 |
As of July 10, 31 states had reported cases to the US Centers for Disease Control and Prevention, though it is not yet clear whether all of them are part of the same outbreak. The CDC said its national count stood at 843 confirmed cases since May 1 while state counts continued to be reviewed.
Why the source is so hard to pin down
Cyclospora cases are slow to count because people may need to remember what they ate weeks earlier, and the parasite does not behave like many bacterial foodborne threats. Genomic testing is more complicated, and some public health systems that track foodborne illness have faced sharp cuts.
Former CDC Director Dr. Robert Redfield told CNN on Monday, “I don’t think it’s in our country’s interest to cut these programs back. Surveillance is sort of the key to early identification.”
The CDC scaled back FoodNet in 2025 after staff and funding cuts to public health agencies. The surveillance network, a partnership involving the CDC, US Department of Agriculture, US Food and Drug Administration, and 10 state health departments, used to collect data on eight pathogens including cyclospora.
Now FoodNet collects information on only two pathogens, salmonella and a dangerous type of E. coli, while the rest are optional. Hilliard, a spokesperson for the US Department of Health and Human Services, said CDC still collects cyclospora data through other surveillance systems.
How cyclospora spreads and why symptoms linger
Cyclosporiasis usually comes from food or water contaminated several weeks earlier, often fresh produce, and it does not typically spread directly from person to person. Michigan said there is currently no evidence linking recreational water activities to this outbreak.
People with the illness may have watery diarrhea, cramping, and bloating for weeks. Dehydration can lead to hospitalization, and treatment is typically a seven- to 10-day course of sulfamethoxazole-trimethoprim, sold as Bactrim or Septra.
The illness is also likely undercounted because some people avoid seeing a doctor or try to wait out the symptoms at home. Diagnosis can be difficult because cyclospora sheds intermittently in stool, so more than one test may be needed and the parasite is not included on all standard lab workups for stomach bugs.
What Michigan officials are doing now
Michigan said the investigation will take time because of the size of the outbreak, the lag between exposure and symptoms, and the complexity of food distribution systems. More than 1,000 interviews have already been completed, and investigators are also reviewing restaurant and grocery receipts to trace what people ate.
Some restaurants have voluntarily pulled certain fresh ingredients from their menus while the investigation continues. Bagdasarian said there has been no nationwide recall of any food suspected of being related to the outbreak.
To reduce risk, Michigan health officials recommend thoroughly washing produce, cooking fruits and vegetables, buying whole heads of lettuce instead of pre-washed lettuce, discarding outer lettuce leaves, and washing inner leaves.
Officials said they are still seeing early signals as the investigation develops, and Bagdasarian noted that the amount of work involved is substantial. “You can just imagine the sheer amount of effort and work that goes into this,” she said.
Correction: A previous version of this story misstated the number of cyclosporiasis cases reported in Ohio since June 1.
