On  June 28, 2018 the Centers for Disease Control (CDC) announced that the outbreak of E. Coli linked to romaine lettuce is over.  This outbreak, which sickened at least 210 people in 36 states, with at least five deaths attributed, is believed to have been caused by romaine lettuce grown and harvested in the Yuma (Arizona) growing region, though the outbreak cannot be explained by a single grower, harvester, processor, or distributor.

Until recently, the source of the contamination was unknown, but the environmental assessment conducted by FDA and CDC has identified the presence of E. coli with “the same genetic finger print as the outbreak strain” in irrigation canal water from the region.  FDA is continuing to investigate.

This is the most recent example of FDA’s use of whole genome sequencing to better understand the source of outbreaks.  The possible connection to irrigation water is bound to cause public health advocates to push for a more immediate compliance date for Agricultural Water Standards than the proposed 2022-2024 (depending on farm size) dates currently under consideration.