Taco Bell has been the shining star of the fast-food business for several years. But now the company is contending with a restaurant’s worst nightmare: an explosive diarrhea outbreak.

Shredded iceberg lettuce sold at some Midwestern Taco Bell locations has been connected with the massive cyclosporiasis parasite outbreak sweeping across parts of the United States. The CDC has identified more than 1,600 cases in the outbreak, including nearly 100 hospitalizations, and states are investigating thousands more. The lettuce was supplied to Taco Bell in Michigan, Ohio, West Virginia, Indiana and Kentucky by Taylor Farms, a source familiar with the investigation told CNN’s Brenda Goodman and Deidre McPhillips Thursday.

Taylor Farms did not respond to CNN’s request for comment.

Taco Bell on Thursday said it removed the potentially compromised lettuce from its nationwide supply chain as a precaution, and it would find a replacement within 24 hours in certain states.

“We are proud to have consistently acted quickly and proactively to protect our guests,” Taco Bell said in a statement.