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Initial Evaluation of Romaine Lettuce from the Yuma Valley


Following the spring 2018 outbreak of E. coli O157:H7, infection was traced back to lettuce grown in the Yuma AZ Valley.  This outbreak involved 210 diagnosed cases in 36 states requiring 96 hospitalizations and 27 cases of hemolytic uremic syndrome with five fatalities.  Yuma Valley supplies most of the leafy greens consumed between November and March.


Following investigations by the FDA, and in consultation with agricultural and food safety experts, changes were made to the irrigation of fields with specific reference to exclusion of runoff from CAFOs.

Recently the FDA conducted assays on 118 samples from specific farms including 26 commercial coolers and cold storage facilities.  All samples were free of Salmonella and a  

Shiga toxin-producing E. coli (STEC) was identified in in one sample. 


Although the initial evaluation is promising, additional surveillance will be necessary for the 2019-2020 season.  In the long term however environmental studies will be required to determine risk factors and to develop appropriate preventive measures.  Over the long term antibacterial treatment such as high-efficiency UV or electron beam treatment may be necessary to provide security for uncooked foods.