Federal health officials have identified lettuce from Mexico served at Taco Bell locations across five US states as a source of a widespread outbreak of the diarrhea-causing parasite cyclospora.The US Centers for Disease Control and Prevention (CDC) on 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 US illness might be caused by a single source.

Taco Bell sign in Encinitas, California, is pictured on Oct. 3, 2016.

A US Food and Drug Administration (FDA) investigation has identified a single supplier of the lettuce. The federal warnings to consumers did not identify the company, but Taylor Fresh Foods said the FDA testing indicated it was “a specific independent farm” affiliated with the company.

The FDA was working with the supplier “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,” it added.Taylor Farms has been tied to foodborne outbreaks in the past. The company on Friday said it was voluntarily removing all iceberg lettuce sourced from central Mexico from the US market.CDC, FDA and public health officials in several states have been investigating a multistate outbreak of cyclospora infections.The illness is not usually life threatening and is typically treated with antibiotics.Federal health officials stressed that other “brands, restaurants, retailers, or distribution channels” could be tied to the outbreak as the investigation continues.Michigan investigators are trying to figure out if the lettuce went to other restaurants or stores, because many of the ill people said they did not eat at Taco Bell, state health officials said.There is no evidence the outbreak “is related to poor food handling or preparation at any single restaurant or fast-food chain,” Michigan health officials said.No deaths have been reported, but Michigan officials said more than 100 people in that state have been hospitalized, and federal health officials say dozens more have been hospitalized in other states.