The US Centers for Disease Control and Prevention (CDC) is adding six more states to the ongoing cyclosporiasis outbreak linked to iceberg lettuce, bringing the total to 15, the Washington Post reported on Tuesday, citing three individuals familiar with the investigation.

An FDA investigation linked the outbreak, which has expanded to nine states, to iceberg lettuce served at Taco Bell restaurants and sourced from privately held Taylor Farms operations in central Mexico.

However, authorities are still looking for other potential sources.

Missouri, which is reporting 1,095 cases, is one of the states being added, the Post reported, citing a state health department spokesperson.

Patients who were interviewed by state and local investigators said they consumed Taco Bell before getting sick, the Post reported, citing a spokesperson.

Information was not immediately available about the five other states, the report said, adding that the individuals spoke on the condition of anonymity to discuss an ongoing investigation.

Outbreak hits record levels

US cyclosporiasis cases have climbed to record levels this year, with the current outbreak among the largest caused by foodborne illness in recent US history. The infection can cause diarrhea, nausea and other gastrointestinal symptoms.

Michigan, the hardest-hit state, reported 11,508 cases on Tuesday, up by more than 200 from the previous day’s update.

The state also reported the first two deaths associated with the outbreak, noting that both individuals had significant underlying health conditions.

The CDC, whose surveillance lags state reporting by several weeks, has recorded 6,707 laboratory-confirmed cases nationwide, as of July 28, along with more than 11,500 suspected cases not yet confirmed through laboratory testing.

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