Why E. coli keeps getting into our lettuce

Why E. coli keeps getting into our lettuce  Washington Post E. Coli Flare-Up Is Largest Multistate Outbreak Since 2006  New York Times E. Coli Outbreak Tied to Romaine Lettuce Grows  WebMD People are throwing out romaine lettuce, but why hasn't there been a recall?  USA TODAYFull coverage

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