It only takes a little to make hundreds sick
– how the bacteria gets into the food supply
Gilroy – Investigators are trailing the nasty bacteria that may have skipped from cows’ intestines to South County spinach leaves and from there to 23 U.S. states, where at least 157 spinach-eaters have fallen ill.
E. coli normally dwells in animal intestines – humans included – but FDA inspectors have yet to determine how the bacterium tainted California farms, the outbreak’s suspected source.
The widespread contamination suggests E. coli arrived early in the distribution chain, at farms or at packing plants. On farms, inspectors are scrutinizing irrigation water and fertilization methods; in plants, sanitary equipment is being examined.
Poor worker hygiene can probably be ruled out as a source, said Jenny Derry, executive director of the Santa Clara County Farm Bureau. She said the state Department of Health Services has pinpointed the bacterial strain to an animal – not human – source.
Dean Cliver, professor of food safety at the University of California, Davis School of Veterinary Medicine, agreed.
“When someone claims they’ve seen field workers relieving themselves over crops, that strikes me as someone with a rich fantasy life,” Cliver said.
Animal feces or even inadequately composted manure could harbor the bacterium, said Cliver. And though all kinds of ruminants, including sheep, goats, deer and elk, carry E. coli, cows are the most likely source, he said, because “we don’t have that many sheep and goats.”
Spinach is more than 90 percent water, added Derry, which makes water an especially significant source of potential contamination.
“Contact with water is constant with this crop,” she explained. The danger lies not at the root, Derry said, but with a “topical application of water,” either during irrigation or through post-harvest water used to wash a picked crop. Most area farms use well water, she added, but a small minority use surface water delivered by canals running parallel to U.S. 101.
Could wells become contaminated?
Possibly, said Mike Villaneva, government industry liaison with the Western Institute for Food Safety and Security, a consortium between the state Department of Human Services, the state Department of Food and Agriculture, and the University of California, Davis.
“If you have a well that’s not well-protected, it could happen,” said Villaneva. Derry also said that a leaky or poorly covered well could become contaminated.
“But it’s very rare for contaminants to enter from the groundwater,” Villaneva said. In addition, “most of the wells here in Salinas Valley are deep-water wells, tested on a regular basis for generic E. coli and other pathogens. They can treat the well and eliminate the bacteria.”
Those protection measures reduce the likelihood that the E. coli outbreak originated in wells.
Flooding has also been suggested as a possible source of fecal contaminants, washed from dairy farms or ranches onto spinach fields. Cliver calls that idea “a long shot.”
“Flooding could well be ruled out as a factor because floods happen, if at all, in the spring,” he explained. “These are the second or third crops off the land after flooding. We’d expect veggies to get contaminated earlier in the year than they have in this instance.” Spinach is typically harvested from five to seven weeks after it’s planted, according to Derry.
Production plants are still under scrutiny, Derry added. Because sanitization is a constant process, even a single instance of contamination could have caused the outbreak, she said.
Investigators are still combing Santa Clara County’s fields, but Villaneva said he doubts they’ll finger the E. coli culprit. Though E. coli has been linked to California spinach or lettuce fields nine times in the past, he said, the exact source has never been pinpointed.
“We’ve never been able to actually match the source of the contaminant in the person with the environmental tests that we’ve done,” he said. In other words, though inspectors may turn up E. coli contamination, it’s hard to establish a conclusive link between such sources and the people infected. “It’s just elusive.”
