The multi-state E. coli outbreak that has been going on since mid-March is said to be the largest in the United States in over a decade.

Have authorities found the main source of the contamination?

Largest Outbreak In Over A Decade

In its latest update, the FDA described the romaine lettuce-linked E.coli outbreak as the largest since the 2006 E. coli outbreak linked to baby spinach. As of May 31, 197 people from 35 states have been affected by the outbreak, 89 of whom were hospitalized.

Of the victims, 20 experienced hemolytic uremic syndrome, which is the most serious complication of E. coli O157:H7 infection. This condition may cause kidney injury and damage or premature death to blood cells.

To date, there are five recorded deaths linked to the outbreak. In a statement, Scott Gottlieb, M.D., FDA commissioner and Stephen Ostroff, M.D., FDA deputy commissioner For Foods and Veterinary Medicine, said that immediate risks for contamination are already gone.

The contaminated romaine lettuce from the Yuma region have already gone through the food supply chain and are no longer available. However, investigation on the outbreak are still ongoing so as to prevent such events from occurring in the future.

Traceback Efforts

The FDA is currently conducting an extensive traceback investigation in hopes of pinpointing the specific source of the E. coli contamination. Such tracebacks entail tracing the contamination backward from the people who became ill until the farm that produced the lettuce. The suppliers, distributors, and processing plants where the product was bagged may also be included in the investigation.

However, the investigation has proven to be rather complicated as there has so far been no obvious convergence along the supply chain that could point to a single source of the contamination.

In fact, the only clear case is that of a correctional facility in which the contamination is directly linked to a single farm, but their lettuce was neither processed nor mixed with lettuce from other farms. The only common link is that all of the lettuce came from farms at the Yuma growing region.

Ongoing Investigation

So far, what authorities know is that the contamination was likely not from a single farm and that it was unlikely to have occurred at the end of the supply chain. Furthermore, they have also established that the source is very likely from, or somewhere close to the Yuma region, possibly through an outside source such as irrigation, pesticide application, and animal encroachment. It’s also possible that the contamination happened right after the produce left the farm.

“Food safety is one of the highest priorities at the FDA. This outbreak is a clear illustration of why that’s the case. It shows the terrible consequences when something goes wrong,” said Gottlieb and Ostroff in the statement.