The Centers for Disease Control and Prevention late Thursday warned consumers not to eat shredded iceberg lettuce from Taco Bell restaurants in Indiana, Kentucky, Michigan, Ohio and West Virginia. A record number of cyclospora cases have been reported in more than 30 states, and experts have said not every recent U.S. illness might be caused by a single source.

A Food and Drug Administration investigation identified a single supplier of the lettuce. The federal warnings to consumers did not identify the company, but a federal official who was briefed on the investigation and not authorized to discuss it told The Associated Press it was Taylor Farms of Salinas, California.

Taylor Farms, which has been tied to foodborne outbreaks in the past, did not immediately respond to a request for comment.

“FDA is working with the supplier of iceberg lettuce to determine if potentially contaminated shredded iceberg lettuce remains on the market,” including in other states, the CDC said. “Taco Bell has committed to stop using any lettuce from the supplier identified by FDA’s traceback investigation.”

In a statement, federal health officials stressed that other “brands, restaurants, retailers, or distribution channels” could be identified as the investigation continues.

CDC, FDA and public health officials in several states have been investigating a multistate outbreak of cyclospora infections.

More than 30 states have reported infections this year, and current data from them shows the number of infections surpassing the record U.S. mark of about 4,700 set in 2019. The illness is not usually life threatening and is typically treated with antibiotics.

On Tuesday, ahead of the federal government’s confirmation, Taco Bell issued a statement saying it had “voluntarily and temporarily removed limited ingredients at select restaurants as a precautionary measure. We will continue to closely monitor the situation and follow the guidance of public health authorities.”

Cyclospora is a microscopic, spherical parasite that commonly causes watery diarrhea “with frequent and sometimes explosive bowel movements,” according to the U.S. Centers for Disease Control and Prevention. Outbreaks tend to occur most often in the late spring and summer.

The heat-loving parasite infects the bowels and spreads through feces. In the past, people have been infected by consuming fruits or vegetables that were exposed to feces-contaminated irrigation water.

The illness, called cyclosporiasis, is less common than foodborne illnesses caused by other germs, including salmonella and E. coli. Many cases are never linked to a specific food or other source and, for years, few U.S. cyclospora outbreaks were reported. But the number started rising about a decade ago, with a particularly notable spike in 2018 and 2019.

Experts say it’s likely that cyclospora cases historically were underreported, in part because some common tests used to check for food poisoning have not been geared to detect cyclospora. They attribute the increasing trend in cases to climate change and better detection.

Taylor Farms also was tied to a 2013 cyclosporiasis outbreak linked to salad mix and a 2024 E. coli outbreak tied to onions served at McDonald’s.

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Stobbe reported from New York.