PHOENIX — The E. coli outbreak linked to romaine lettuce from Yuma appears to have been caused by infected water canals in the area, public health officials said Thursday.
The Centers for Disease Control and Prevention released its final update on the situation Thursday and said the outbreak — the largest E. coli outbreak in more than a decade — "appears to be over."
Since the initial announcement of the multistate outbreak on April 10, the bacteria infected 210 people across 36 states, according to the CDC. The outbreak caused five deaths and 96 hospitalizations, including 27 people who developed a type of kidney failure.
Federal and state health officials had previously traced the lettuce to farms in the Yuma region, including Harrison Farms. On Thursday, they announced the results of their environmental assessment of samples from Yuma's water, soil, and manure.
"CDC laboratory testing identified the outbreak strain of E. coli O157:H7 in water samples taken from a canal in the Yuma growing region," the report read.
The water samples were found to be "closely related genetically" to the E. coli strains in infected people.
Attorney representing victims 'not necessarily surprised'
Food-safety lawyer Bill Marler is representing 105 of the people sickened by the same strain, including the families of two who have died. He said he has been working to trace the path of the lettuce eaten by his clients back to a single source.
This is the first E. coli outbreak tied to an irrigation canal that he can recall.
Marler said given the number of fields and farms implicated in the Food and Drug Administration's findings, he was "not necessarily surprised" to hear the contamination stemmed from widespread environmental causes.
He pointed to how the last major E. coli outbreak caused by leafy greens — the spinach infections of 2006 — was linked to one single farm that had an intrusion of wild pigs.
"Here, there were so many fields and farms implicated that it really indicated that it was not just one contamination event like some pigs getting into the field. It was a broader issue, some environmental issue," Marler said.
"Water contamination makes a lot of sense."
A long-term problem for Yuma farmers?
Marler said he expects the finding will cause long-term challenges for Yuma.
Given this strain of E. coli is nearly always linked to cattle, Marler said he assumes there are feedlots or cattle farms upstream that caused the canal to become infected.
"Here, it's like, 'What are you going to do?' " Marler said. "It's either that you're going to have to treat the water before you irrigate or you're going to have to take a hard look at what's upstream."
E. coli is the abbreviated name for the bacteria Escherichia coli, which the CDC says is found in "the environment, foods, and intestines of people and animals." E. coli are a diverse collection of bacteria — most of which are harmless — but others of which can cause diarrhea, severe infections and even death.
The CDC and the FDA are continuing to test other environmental samples "to learn more about how the E. coli bacteria could have entered the water and ways this water could have contaminated romaine lettuce in the region."
Representatives from the CDC and the Arizona Department of Health Services did not immediately respond to The Arizona Republic's requests for comment.