Indiana is among five states where health officials are warning Taco Bell customers about shredded lettuce linked to a cyclosporiasis outbreak.

The Centers for Disease Control and Prevention said Thursday lettuce imported from Mexico and served at select Taco Bell restaurants in Indiana, Kentucky, Michigan, Ohio, and West Virginia has been identified as the source of the outbreak.

Dr. Kavita Patel says it could still take time to control the outbreak.

“It could end several weeks after they’ve identified a source and have been able to issue those consumer safety recalls or being able to make sure that any source is off the market,” she said.

The CDC has counted thousands of cases in those five states.

Cyclosporiasis is less common than foodborne illnesses caused by other germs, including salmonella and E. coli. It is an illness caused by the microscopic parasite Cyclospora cayetanensis.