Today the Centers for Disease Control and Prevention (CDC) announced the findings of a multistate outbreak of E. coli O157:H7 infections linked to romaine lettuce. The E. coli O157:H7-contaminated lettuce was sold to consumers primarily at various Schnucks salad bars between October 5 and October 24, 2011.
The investigation was a collaboration between the CDC, Missouri public health and agriculture, other states, and the FDA. They found that romaine lettuce served on salad bars at all locations of Schnucks (grocery store Chain A) had come from a single lettuce processing facility via a single distributor. This indicates that contamination of romaine lettuce likely occurred before the product reached the grocery store locations.
As of December 4, 2011, 60 persons infected with the outbreak strain of E. coli O157:H7 have been reported from10 states. The number of ill persons identified in each state is as follows: Arizona (1), Arkansas (2), Georgia (1), Illinois (9), Indiana (2), Kansas (3), Kentucky (1), Minnesota (3), Missouri (37), and Nebraska (1).
Among the 45 ill persons with available information, 30 (67%) were hospitalized, and 2 developed hemolytic uremic syndrome (HUS). No deaths have been reported.
According to the CDC’s announcement:
Ill persons reported purchasing salads from salad bars at grocery store Chain A between October 5 and October 24, 2011. A total of 9 locations of grocery store Chain A were identified where more than one ill person reported purchasing a salad from the salad bar in the week before becoming ill. This included 2 separate locations where 4 ill persons reported purchasing a salad at each location. For locations where more than one ill person reported purchasing a salad from the salad bar and the date of purchase was known, dates of purchase were all within 4 days of other ill persons purchasing a salad at that same location. Chain A fully cooperated with the investigation and voluntarily removed suspected food items from the salad bar on October 26, 2011, out of an abundance of caution. Romaine lettuce served on salad bars at all locations of grocery store Chain A had come from a single lettuce processing facility via a single distributor. This indicates that contamination of romaine lettuce likely occurred before the product reached grocery store Chain A locations.
The FDA and several state agencies conducted traceback investigations for romaine lettuce to try to identify the source of contamination. Traceback investigations focused on ill persons who had eaten at salad bars at several locations of grocery store Chain A and ill persons at university campuses in Minnesota (1 ill person) and Missouri (2 ill persons). Traceback analysis determined that a single common lot of romaine lettuce harvested from Farm A was used to supply the grocery store Chain A locations as well as the university campus in Minnesota during the time of the illnesses. This lot was also provided to a distributor that supplied lettuce to the university campus in Missouri, but records were not sufficient to determine if this lot was sent to this university campus. Preliminary findings of investigation at Farm A did not identify the source of the contamination. Farm A was no longer in production during the time of the investigation.