The outbreak update was in response to the spring strain of E. coli O157:H7 that was found in contaminated romaine lettuce. The first reports came in on March 13 and by early June the outbreak had sickened over 200 people and killed five as it spread out over 36 states. The outbreak was not discriminatory in its victims, sickening people ranging from one to 88 years of age.
As the most severe outbreak of E. coli O157:H7 since 2006, the strain led to the hospitalization of 96 people. 27 of these people also developed kidney failure. What was particularly interesting and worrisome about this outbreak is that not everyone who became sick actually ate the contaminated lettuce. Some cases were reported among people who had contact with those who fell ill after consuming the tainted produce.
The CDC worked in partnership with the US Food and Drug Administration (FDA) to trace the outbreak back to a growing region in Yuma, Arizona. Known for its warm and dry conditions, the region is responsible for growing the overwhelming majority grown during the winter months in the US. The investigation into the matter revealed that the outbreak could not be traced back to one single farm or supplier. Instead, it was spread across multiple supply chains, convoluting the investigation and leading investigators to suspect that the outbreak might be due to something amiss in the water supply to the region.
Further investigation revealed that samples obtained from the irrigation canals tested positive for the same strain of bacteria found in the infected lettuce. The FDA is still in the process of determining how the water initially became infected. To determine the source, the group is currently testing samples of cow manure and soil near to the water supply.