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E. Coli Link Is Found in Cattle Feces

A genetic match to the strain responsible for three recent deaths is discovered near one of the farms suspected of growing tainted spinach.

October 13, 2006|Rong-Gong Lin II and Marla Cone | Times Staff Writers

State and federal officials probing the recent E. coli outbreak linked to spinach said Thursday that they have found the genetic match of the bacterium in cattle feces near a farm suspected of supplying the tainted greens.

The discovery represented a major breakthrough for investigators, who in years of tracking outbreaks have never before found a matching E. coli sample in the environment near where the tainted spinach or lettuce was grown.

The finding did not answer how the spinach was contaminated with the virulent strain of E. coli that has killed three and sickened nearly 200 people nationwide.

Still, "finding a close or identical strain is sufficiently rare that it speaks volumes about the likely source," said UC Davis plant pathologist Trevor Suslow, who has studied pathogens in spinach and lettuce in the Salinas Valley.

The breakthrough underscored a key concern of health officials: the proximity of cattle, whose feces can carry the dangerous bacterium, to farms growing ready-to-eat greens.

"We do not have a smoking 'cow' at this point," said Kevin Reilly, deputy director for prevention services at the California Department of Health Services.

But, he said, at the farm neighboring the cattle pasture where the strain was isolated, "the fields are surrounded, frankly, by pastures where livestock are kept."

The spinach farm's operator leases its land from the cattle ranch owner, and the two operations are separated by a paved road and fences.

The fecal samples that matched the E. coli strain in the outbreak were found in a pasture about half a mile to a mile from the spinach field.

The closeness of cattle and leafy green operations in the Salinas Valley area is "not uncommon," Reilly said.

Not all of the four farms suspected in the outbreak have both spinach and livestock operations, Reilly said. Local agricultural officials say most cattle ranching is done in the foothills, while leafy greens are largely grown in the fertile valley bottom.

"The proximity ... has always been an issue of concern," said Robert Brackett, director of the U.S. Food and Drug Administration's food safety center.

Officials and food safety experts said Thursday's announcement raises a question: Should minimum distances be set between cattle pastures and fields where leafy greens are grown?

"If you have cattle in a pasture that's adjoining where you're growing lettuce or spinach crops, you have a problem," said Caroline Smith DeWaal, food safety director for the Center for Science in the Public Interest, based in Washington, D.C.

"You have to create zones around the field to make sure the cattle manure can't get into the farm field," she said. "To narrow the solution to one field or one group of cattle would be missing the more systemic problem that may exist in the Salinas Valley."

Even before the announcement, some farmers and cattlemen had informally expressed concerns about the possibility of having to create buffer zones between fields and pastureland.

"You're talking about huge amounts of private property," said Bob Perkins, executive director of the Monterey County Farm Bureau.

Matt Byrne, the California Cattlemen's Assn.'s executive vice president, said cattle ranchers have been putting practices in place over the last decade to prevent runoff and water contamination. Those efforts include researching the slope of land, fencing off creek sides and planting buffer zones, he said.

The state Department of Food and Agriculture has no regulations regarding the distance between cattle and fresh produce operations, said spokesman Steve Lyle.

Having a field of spinach neighboring a cattle range does violate "good agricultural practices," a voluntary set of national guidelines on food safety practices, said Alejandro Castillo, an associate professor of food microbiology at Texas A&M University.

Agricultural experts say spinach and lettuce growers should be examining their fields for visible feces and destroying those crops if they find it.

"Something tells me that somebody didn't do their job," Castillo said.

Brackett, of the FDA, said instituting a minimum distance between cattle and farms "is something we will take into consideration as we go forward."

The spinach outbreak is by far the most widespread of nine E. coli outbreaks linked to the Salinas Valley. Since 1995, there have been 20 spinach- or lettuce-related outbreaks blamed on a virulent strain of E. coli, O157:H7, which can cause kidney failure.

Days after investigators issued a nationwide alert on bagged spinach, they identified the suspect greens as coming from Natural Selection Foods, a processor of bagged spinach in San Juan Bautista, Calif.

Authorities narrowed the source of the spinach first to nine farms, then to four, in Monterey and San Benito counties. Officials have not identified the farms, which have suspended spinach harvests.

Investigators have been putting in 18-hour days for three weeks, collecting more than 650 samples on and near the farms.

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