Arizona leads the nation in leafy greens production during the winter months, contributing approximately $2 billion to Arizona’s economy annually. But after several E. coli outbreaks last fall in California, the leafy greens industry was decimated. 

Economic losses from a 2018 E. coli outbreak in romaine lettuce have been estimated at $350 million for the industry.  The 2019 outbreak drove up prices of the vegetable to $32.55 per carton, almost twice the average per carton price the year before, according to the USDA.

Forty people in 16 states, including two in Arizona, were infected with E. coli last fall from romaine lettuce grown in Salinas, California, according to the Centers for Disease Control and Prevention. 

From September through December, at least 167 people were infected and 85 hospitalized, including 15 who developed hemolytic uremic syndrome a type of kidney failure. The CDC said the outbreak was the Shiga toxin-producing E. coli, the most common form found in the United States. 

By January, consumers were told it was OK to eat romaine lettuce from the region again, but no reason for the outbreak was given at the time.

A just released report from the Food and Drug Administration says runoff from nearby cattle is responsible for tainting lettuce farms.

Scott Horsfall is CEO of California Leafy Greens Marketing Agreement, a quasi-governmental group that oversees California’s $2.4 billion lettuce industry is continuing its review of members’ compliance with food safety rules. “Much of what is in the FDA’s report is already widely known among growers,” Horsfall said.

“What they didn’t find was any sort of definitive link between any pathogens they found on pasture land and the outbreaks that took place. So, we’re still trying to figure out exactly how these things might have happened, but there are clues.There is information that we will make use of going forward,” he said

Horsfall said industry standards are already stricter than the FDA’s. 

The coalition formed after a deadly E. coli outbreak in 2006 and already requires members to test water sources monthly and prohibits irrigation with surface water during the critical final stages of cultivation, according to Horsfall.

The FDA’s investigation into the fall 2019 outbreaks led to several California farms, according to report.

Key findings include:

• Each of the three outbreaks was caused by distinctly different strains of E. coli O157.H7, according to whole genome sequencing.
• Traceback identified a common grower with multiple ranches/fields that supplied romaine to multiple businesses associated with the three outbreaks.
• Outbreak A’s strain was found in two brands of salad bags with romaine.
• Outbreak A’s strain was found in a fecal-soil sample taken from a cattle grate less than two miles upslope from a farm with multiple fields tied to the outbreaks.
• Other E. coli strains that were not linked to the three outbreaks were found near romaine crops, including two samples from a border area of a farm downhill from cattle grazing land, and two samples from on-farm drainage basins.