The Centers for Disease Control and Prevention is preparing to expand its ongoing cyclosporiasis outbreak investigation to 15 states, according to a report by The Washington Post. The development would add six states to the widening outbreak.

The outbreak has been associated with lettuce served at Taco Bell restaurants and lettuce sold in grocery stores. However, available reporting indicates that the cases may not all stem from one contaminated product or a single source.

Cyclosporiasis is a foodborne illness connected to the outbreak investigation, but the precise scope and sources of the reported cases remain under review. The CDC’s anticipated update reflects the continuing effort to identify links among cases across multiple states.

As the investigation expands, health officials are assessing whether separate food exposures could explain the illnesses rather than one item being responsible for every case.