State and federal officials probing the recent \o7E. coli \f7outbreak 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 \o7E. coli \f7sample 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 \o7E. coli \f7that 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 \o7E. coli \f7strain 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?
