As cyclospora disease surges to record cases, Michigan officials believe eye lettuce may be to blame
Infections with Cyclospora, the parasite that causes diarrhea, are surging, with state data showing 2026 is already the worst year for reported cases nationwide.
More than 30 states have reported infections this year, with the latest data from those states showing infections exceeding the U.S. record of about 4,700 set in 2019. The disease is usually not life-threatening and usually requires treatment with antibiotics.
Health officials have not yet clearly determined what caused the infection. On Tuesday, federal health officials said there may be different infection patterns in different places, although they believe cases in at least four states — Michigan, Ohio, Kentucky and West Virginia — are linked.
Michigan officials blame lettuce
In Michigan, where more than 3,300 cases have been reported, officials said early information suggests lettuce or salad greens may be to blame.
After interviews with more than 1,000 patients, “early information suggests lettuce is a common product that comes up frequently during investigations,” said Natasha Bagdasarian, chief medical executive for the Michigan Department of Health.
Because of this commonality, and because the produce has been behind some past cyclospora outbreaks, Michigan officials recommend consumers buy whole heads of lettuce, discard the outer layers and wash the remaining parts thoroughly. They also advise people to avoid bagged lettuce and pre-mixed salad kits.
On Tuesday, the Taco Bell restaurant chain issued a statement saying it “has voluntarily temporarily removed limited ingredients from select restaurants as a precautionary measure. We will continue to monitor the situation closely and follow the guidance of public health authorities.”
In a conference call with reporters Tuesday, federal health officials did not directly answer questions about whether they were considering Taco Bell or any specific food supplier or distributor.
Donald Prater, acting deputy commissioner for food at the U.S. Food and Drug Administration, responded: “The FDA is of course continuing to conduct traceback investigations on a variety of agricultural products, including the location where the case patient was reported before becoming ill.”
Cyclospora causes ‘explosive’ diarrhea
Cyclospora is a tiny, spherical parasite that often causes watery diarrhea “associated with frequent and sometimes explosive bowel movements,” according to the Centers for Disease Control and Prevention. Outbreaks most commonly occur in late spring and summer.
This heat-loving parasite infects the intestines and is spread through feces. In the past, people became infected by eating fruits or vegetables that came into contact with fecal-contaminated irrigation water.
The disease, called cyclosporiasis, is less common than other foodborne illnesses caused by bacteria such as salmonella and E. coli. Many cases are not linked to specific foods or other sources, and for many years, few Cyclospora outbreaks have been reported in the United States. But the numbers started rising about a decade ago, with peaks in 2018 and 2019 being particularly significant.
Experts say cyclospora cases may have been historically underreported, in part because some common tests used to check for food poisoning are not adapted to detect cyclospora. They attribute the trend of rising cases to climate change and better testing.
2019 was the worst year for infections
The U.S. had its worst year for infections in 2019, when about 4,700 cases were reported, according to federal confirmed and probable case data.
The Centers for Disease Control and Prevention keeps those numbers, but they traditionally lag behind the data released by various city and state health departments dealing with local outbreaks in real time. On Tuesday, CDC officials issued a health alert saying that since May 1, the agency was aware of 1,645 confirmed domestic cases and more than 5,100 cases that require further analysis to confirm whether the infection is spreading in the United States. The reports came from 34 states, and no deaths have been reported, the CDC said.
Gwen Biggerstaff, deputy director of the CDC’s Division of Foodborne, Waterborne and Environmental Diseases, told reporters that the true number of cases may be higher than reported so far because some people may have milder forms of the disease but do not seek treatment.
It may take days to weeks for people exposed to the parasite to develop symptoms. It’s unclear how infected people are currently, or whether many of the exposures occurred earlier. But Biggerstaff said officials expect the number of cases to continue to grow throughout August.
The CDC also released investigative information about the outbreak affecting the four states.
The federal alert did not detail how many reports there were in each state. But officials in Michigan have reported more than 3,300 cases, officials in northwest Ohio said they have reported more than 1,100, New York City officials have counted more than 400 and Illinois has reported more than 200.
Officials do not believe everything can be linked to a common source. In Illinois, for example, more than half of those infected said they had traveled outside the United States, and at least some may have been infected elsewhere.
But Michigan officials believe much of that may be due to related domestic outbreaks. CDC officials did not elaborate on why they currently believe the cases in Michigan, Ohio, Kentucky and West Virginia are part of the same outbreak.
