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Email Content: Poultry Industry News, Comments and more by Simon M. Shane

CDC Warning Over Romaine Lettuce


Romaine lettuce is back in the news following an E.coli outbreak involving 32 cases infected with an STEC strain 0157:H7. Cases were diagnosed from October 8th through the end of the month in 11 states. Of the patients investigated, 13 have been hospitalized and one developed hemolytic uremic syndrome. The public health agency of Canada has identified 18 cases with the same DNA fingerprint of E.coli 0157:H7 in Ontario and Quebec. Preliminary investigations have indicated that romaine lettuce is the likely source of the outbreak. Based on harvest times and distribution, it is most probable that specific counties in California are the source of the infected product.

The CDC has warned consumers not to eat romaine lettuce although FDA Commissioner Dr. Scott Gottlieb stated on November 20th that “It is frustrating that the FDA cannot tie the outbreak to a specific grower, but we have confidence that it is tied to romaine lettuce.” STEC can produce severe clinical effects in children under five, adults over 65 and those with immunosuppression.

The strain isolated from patients in the October/November outbreak is similar to a 2017 outbreak strain, but different from the E.coli 0157:H7 responsible for an earlier 2018 outbreak confirmed to have been associated with romaine lettuce grown in the Yuma Valley of Arizona. In this outbreak, the infective organism was spread from cattle feedlots to surface water used to irrigate lettuce crops.

 There is no simple method of decontaminating leafy vegetables. It is possible to ensure freedom from E.coli and Salmonella by subjecting product to approved doses of irradiation using electron beam technology analogous to an X-ray. Bulk product on pallets would have to be treated with cobalt60 gamma irradiation to effectively decontaminate product. There is considerable consumer resistance to any form of irradiation, but eventually there will have to be a tradeoff between treatment to achieve a pathogen-free product or face reoccurring outbreaks. Voluntary recommendations limiting proximity of concentrating animal feeding operations and fields growing produce may ameliorate the problem but will not eliminate risk.  

Copyright 2019 Simon M. Shane