Lettuce supplied to Taco Bell restaurants by Taylor Farms has been linked to the cyclosporiasis outbreak affecting 34 states, according to multiple reports.

Federal and Michigan officials had begun investigating the Mexican American-style fast-food chain earlier this week, the Washington Post reported, but reports of Taylor Farms’s implication in the outbreak first broke Thursday evening. The investigators have been probing what has caused the uptick in cyclosporiasis cases across the United States, as the Centers for Disease Control and Prevention has recorded at least 1,645 cases this year.