Federal health officials are urging the public to stop eating lettuce from certain Taco Bell restaurants that get fresh produce from a supplier in Mexico, as the investigation into an escalating outbreak of cyclosporiasis — a stomach bug that causes weeks of severe diarrhea — continues.

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“Do not eat shredded iceberg lettuce from Mexico served at Taco Bell locations in Indiana, Kentucky, Michigan, Ohio and West Virginia,” the Food and Drug Administration said in an alert Friday. The alert did not name Taco Bell’s lettuce supplier, however two sources with knowledge of the federal investigation said it’s Taylor Farms.

It’s unclear whether produce from Taylor Farms could be linked to cases in other states with outbreaks. Health officials have said it’s likely that multiple outbreaks are ongoing in at least 34 states.

The Centers for Disease Control and Prevention said in emailed statement Friday that shredded lettuce sold in grocery stores or served in other restaurants is not affected.

Nationwide, nearly 7,000 people may have been sickened with the stomach bug that causes weeks of severe diarrhea. As of Friday, the Centers for Disease Control and Prevention had confirmed with 1,644 of those cases and was investigating more than 5,100. No deaths have been reported.

In an emailed statement, Taco Bell said it has voluntarily removed lettuce suspected in the outbreak from its supply chain nationwide “indefinitely” and will replace it in selected states within the next day.

The company did not name Taylor Farms in its statement, but said it believes “public health is a shared responsibility among restaurants, their suppliers, and authorities, and we are proud to have consistently acted quickly and proactively to protect our guests,” the statement read. “We encourage all relevant restaurants, retailers, and foodservice operators to do the same.”

Taylor Farms did not immediately respond to a request for comment.

The link between Taylor Farms and the outbreak was first reported by the Washington Post.

Michigan has been hit the hardest in the outbreak, with 4,312 cases as of Friday. (The CDC’s count often lags behind state counts.) The state Health Department said that 102 people in Michigan have had to be hospitalized.

Michigan health officials previously flagged lettuce and salad greens as a potential source based on more than 1,000 interviews with people who’ve tested positive.

Getting to the source of the outbreak has been difficult, as the incubation period for the parasite to make a person sick can be up to two weeks.

This isn’t the first time Taylor Farms has been connected to a cyclosporiasis outbreak. In 2013, 631 people in 25 states were sickened by a salad mix linked to the company, health officials concluded. Many of the illnesses occurred in Iowa and Nebraska among people who’d eaten at Olive Garden and Red Lobster. The outbreak was eventually traced to a salad mix from a Taylor Farms processing plant in Mexico.

Health officials also determined that Taylor Farms was also at the root of a 2024 E. coli outbreak linked to slivered onions on McDonald’s Quarter Pounder hamburgers. According to the Food and Drug Administration, 104 people were sickened in 14 states in that outbreak. Nearly three dozen were hospitalized, four people, including at least one child, developed severe kidney problems. One person, an older adult from Colorado, died.