March 23, 2007 -- Exactly how E. coli got on fresh bagged spinach, killed three people, and sickened 205 people in 26 states last fall remains a mystery.
The FDA and California's Department of Health Services (CDHS) today issued their final report on their joint investigation of the E. coli outbreak that temporarily took fresh spinach off shelves nationwide last fall.
The report highlights several possible risk factors for how the spinach got tainted with E. coli 0157:H7. But it doesn't pinpoint precisely how the spinach got contaminated.
"Very clearly, the problem is multifaceted," the FDA's David Acheson, MD, said in a news conference.
Acheson is the chief medical officer for the FDA's Center for Food Safety and Applied Nutrition.
"The in-depth report illustrates a number of areas which could have been responsible for contributing to the problem," Acheson said.
Potential Risk Factors
Risk factors noted in the report include wildlife (including wild pigs) and domestic animals (including a cattle ranch) near a spinach field linked to the outbreak.
E. coli lives in animals' intestines and spreads through contaminated feces.
Harvesting, shipment, and processing could also have played a role, notes Kevin Reilly, DVM, MPVM, deputy director of preventive services for California's Department of Health Services.
"Along the entire continuum, there was potential for contamination or amplification of contamination," Reilly says, adding that no signs of contamination were found at the processing plant.
"Clearly, product that was contaminated went through the processing plant and any contamination that may have been there was not eliminated in the processing," Reilly says.
"What relative roles each of these played, we don't know for sure," he says. "Unfortunately we were not there on the date of harvest and the date of processing."
No produce is currently being grown on the field linked to the outbreak, Reilly notes.
Call for Good Agricultural Practices
Good agricultural practices make the risk of such outbreaks "markedly lower," but it doesn't rule out future outbreaks, Reilly says.
"Is it 100% preventative? No. Nothing is 100%," he says, calling for good agricultural practices to be used "every day, on every farm."
A single breakdown in those practices could lead to another outbreak, Reilly notes. He and Acheson also call for more scientific research to learn how E. coli gets onto and survives on produce.
The FDA recommends that all produce be thoroughly washed before eating.
But Reilly points out that rinsing bagged produce won't necessarily remove E. coli and might even spread contamination.
"Rinsing it is not a guarantee of removing that contamination," Reilly says. "The emphasis in production is to prevent that from being there in the first place."
"Good practices in the kitchen are critical to food safety," Reilly says. "Our current recommendations are that it is not necessarily to re-rinse product coming out of those bags. Rinsing of that product would not be a guarantee or an assurance that you're reducing the risk."