A new report by federal health officials indicates several E. coli food poisoning outbreaks linked to romaine lettuce may have been the result of waste runoff from cattle fields adjacent or at higher elevations than the nearby growing fields.
The FDA issued a report on May 21, outlining the findings of an investigation into three romaine lettuce E. coli outbreaks that occurred in 2019, including a series of recommendations for produce farmers that are designed to mitigate fecal runoff problems that may impact their crops.
Inspectors reviewed three separate E. coli outbreaks that occurred in 2019, all impacting romaine lettuce products grown in the Salinas, California growing regions.
Accord to traceback investigations, which examined the contaminated lettuce products was grown, many of the fields were in close proximity to cattle fields. During the course of the investigation, officials found that one of the strains of E. coli O157:H7 linked to the outbreak was detected in a sample on public land where cattle consistently grazed less than two miles upslope from a produce farm.
While the agency could not definitively tie the strains of E coli to the outbreaks, they determined these adjacent or elevated cattle fields could have been the source of contamination due to natural runoff coming downhill into the fields.
E. coli is a foodborne bacteria which normally lives in the intestines of people and animals and are usually harmless, and serve an important part of a healthy human intestinal tract. However, some strains of E. coli can be pathogenic and are often found in the feces of cattle, sheep, pigs, deer, dogs and poultry.
As a result of the findings into the Salinas, California, growing region outbreak, officials issued a series of recommendations to the leafy greens industry to evaluate the factors that could contribute to recurring outbreaks.
Those recommendations include preventing contamination from uphill cattle grazing lands by adding barriers such as berms, diversion ditches, and vegetative strips; assessing adjacent lands and the runoffs that could be impacting irrigation supply; and performing a root cause analysis when a food-borne pathogen is identified.
Over the last several years, officials have identified clusters of E. coli outbreaks involving romaine lettuce and other leafy greens, specifically around the Thanksgiving holiday time. The outbreaks have results in several hundred illnesses and hospitalizations.
E. coli causes mild to severe diarrhea and abdominal cramps, bloody stools, and sometimes minor fevers lasting between five and 10 days. For individuals like young children, the sick and the elderly, the consequences may be more severe due to weakened immune systems, potentially resulting in the infection causing a serious condition known as Hemolytic Uremic Syndrome (HUS), which may lead to kidney failure or even death.
Each year, officials estimate approximately 74,000 illnesses are caused by E. coli, resulting in thousands of hospitalizations and dozens of deaths.