U.S. health officials are investigating iceberg lettuce supplied to Taco Bell by Taylor Farms as a possible source of a growing multi-state outbreak of cyclosporiasis, a parasitic illness that can cause prolonged diarrhea and other gastrointestinal symptoms.

According to federal health authorities, the outbreak has affected multiple states, including Indiana, Kentucky, Michigan, Ohio and West Virginia. Nationwide, thousands of suspected cases have been reported, with more than 1,600 infections confirmed while thousands of additional cases remain under investigation. No deaths have been reported.

The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) are working alongside state health departments to determine the exact source of the outbreak. Investigators are examining whether contaminated iceberg lettuce distributed through the food supply chain may be responsible for illnesses reported across the affected states.

In response to the investigation, Taco Bell announced that it has voluntarily removed the suspected lettuce from its restaurants nationwide as a precautionary measure. The company said it is replacing the product in selected locations while cooperating with public health officials.

Michigan has reported the highest number of cases during the outbreak, with health officials confirming thousands of infections and more than 100 hospitalizations. Earlier investigations by the state identified lettuce and other leafy greens as potential sources based on interviews with affected patients.

Health experts say tracing the outbreak has been challenging because cyclosporiasis has an incubation period of up to two weeks, making it difficult for patients to recall exactly what they ate before becoming ill.

Taylor Farms has previously been linked to foodborne illness investigations, including a 2013 cyclosporiasis outbreak connected to packaged salad products and a 2024 E. coli outbreak associated with onions supplied for McDonald's Quarter Pounder hamburgers. However, investigators have not yet confirmed whether the current outbreak is directly linked to the company.

Federal and state health officials continue to investigate the outbreak and are urging consumers to follow food safety guidance while the source of the contamination is identified.