US health authorities have widened their probe into a cyclosporiasis outbreak tied to iceberg lettuce from central ​Mexico after detecting cases in three additional states, ‌raising the total to 20 states, the FDA and CDC said on Thursday.

The outbreak, linked to iceberg lettuce served at ​Taco Bell restaurants and sourced from Taylor Farms’ ​operations in Mexico, has grown to 11,458 cases, ⁠including 495 hospitalizations.

The Food and Drug Administration said Georgia, Tennessee, and Texas have been added to the list of affected states since the last update a week earlier. The recent cyclosporiasis outbreak is among the largest foodborne illness events in recent U.S. history and has shaken consumer confidence around fresh produce.

Cyclosporiasis can lead to diarrhea, nausea and other gastrointestinal symptoms.

The FDA said it is continuing onsite inspections and sampling at iceberg lettuce farms and the processing facility in Mexico, in coordination with Mexican officials. The agency said it is confident that all recalled iceberg lettuce has been removed from the market, and added that it will continue to work with federal, state, and international partners to investigate the outbreak.

Michigan has been the hardest hit, reporting two related deaths in people with significant underlying health conditions. The Michigan health department reported 14,510 cases linked to the cyclosporiasis outbreak, up 233 cases — about a 2% increase — since its update last week.