In late 2024, CDC, FDA and their state and local public health partners investigated an outbreak of E. coli O157:H7 infections associated with romaine lettuce.

The outbreak was first detected in November 2024, when public health officials in St. Louis County and Missouri investigated an outbreak of E. coli O157 infections associated with Andre's Catering and Banquets. Ill persons attended one of 5 separate events hosted or catered by the company. Two of those were attended by the Rockwood Summit High School community. Cases began appearing after a school band event held on November 6. Other events linked to the outbreak include a November 7 band banquet, a veterans' event held on November 8 and funerals held on November 8 and November 9. All were catered by Andre's. All events included the same menu items with a few modifications. Investigators conducted a retrospective cohort study of 2 event and found that salads were the only statistically significant menu item across both events.

Additional cases not associated with Andre's Catering and Banquets were detected by WGS in 15 states: AR (2), CO (1), IL (7), IN (8), KS (1), KY (1), MO (50), MT (1), ND (2), NE (3), OH (8), PA (1), SD (1), TN (1), and WI (2). All were related within 0-4 alleles by cgMLST. Isolation dates ranged from November 4, 2024 to November 30, 2024. In total 89 cases were identified. Outcome information was available for 74 cases, of which 36 (49%) were hospitalized. There were 7 reported cases of Hemolytic Uremic Syndrome, and one death.

CDC deployed a focused questionnaire on November 26, 2024. Twenty-seven questionnaires were returned. Epidemiologic information was available for 65 cases, of which 60 (95%) reported consuming any type of leafy green prior to illness. Of 57 cases who could remember the exact type of leafy green consumed, 50 (88%) consumed romaine lettuce. This was statistically significantly higher than the background rate of 49% from the FoodNet Population survey.

Traceback investigation determined that a sole processer sourced romaine lettuce from a single grower that would have been available at all points of service during the timeframe of interest. Through analysis of records, four lots of romaine lettuce were implicated, resulting in confirmation of romaine lettuce as the vehicle.

The investigation was closed on January 15, 2025.

The outbreak was assigned CDC Cluster code 2411MOEHX-2 and was reported to NORS with NORS ID: 511856.