Federal health officials have identified shredded iceberg lettuce served at certain Taco Bell restaurants as the source of a multistate outbreak of cyclosporiasis, an intestinal illness that can cause prolonged watery diarrhea.

The Centers for Disease Control and Prevention is warning consumers not to eat shredded iceberg lettuce from Taco Bell locations in Indiana, Kentucky, Michigan, Ohio and West Virginia. Georgia is not included in the current warning.

The Food and Drug Administration traced the lettuce to a single supplier in Mexico, although the company’s name has not been released. Taco Bell has agreed to stop using lettuce from the supplier while federal officials investigate whether potentially contaminated products remain available elsewhere.

More than 30 states have reported cyclospora infections this year, although not every case has been connected to Taco Bell or a specific food source.

Cyclospora is a microscopic parasite that infects the intestines. Symptoms may include frequent watery diarrhea, stomach cramps, nausea, fatigue, loss of appetite and weight loss. The illness is generally treated with antibiotics and is rarely life-threatening.

Anyone experiencing persistent or severe symptoms should contact a healthcare provider.