THURSDAY, Oct. 12, 2006 (HealthDay News) -- Three samples of cattle fecal matter from one ranch in California's Salinas Valley have tested positive for the same strain of E. coli bacteria that sickened 199 people in 26 states and left three dead after they ate contaminated spinach.
It's not certain that the ranch was the source of the outbreak, but it's an important lead in the continuing investigation, U.S. and California health officials said during a Thursday evening teleconference.
"We do not have a 'smoking cow' at this point," said Dr. Kevin Reilly, deputy director of the prevention services division for the California Department of Health Services. "We do not have a definitive cause-and-effect, but we do have an important finding."
This is the first time that a strain of E. coli implicated in an outbreak in California's produce-growing region has been linked to a likely source, Reilly said. An additional 650 other specimens are being tested for the bacteria, he said.
The ranch in question is one of four still under scrutiny in San Benito and Monterey counties. Five other ranches have been cleared, but the investigation is ongoing.
"The investigation is not concluded in any way, shape or form," Reilly said.
"It is our expectation that no farm should feel like they are off the hook," said Robert Brackett, director of the U.S. Food and Drug Administration's Center for Food Safety and Applied Nutrition. "These are ready-to-eat products that are consumed without any cooking, and it is absolutely essential that all farms in the country are doing absolutely everything they can to make sure this never happens again."
The ranch that yielded the positive specimens included both a beef cattle operation as well as fields where spinach and other ready-to-eat produce were grown. The fecal-matter specimens were found half a mile to a mile from the produce fields themselves. The produce fields themselves abutted the livestock pastures, Reilly said.
It's unclear how the contaminated fecal matter could have been transported to the field, but investigators are not ruling anything out. It could have been wandering livestock, substandard worker hygiene, irrigation practices or even wild boar, officials said.
"We don't know if wild swine are playing a role or not, but we do know that on this particular ranch, there is a very large population of wild boar, and we have witnessed on this site that they have torn through fencing and under fencing and have the ability to access the field," Reilly said. "We don't know if that is the source of contamination. It is a potential source, most definitely," he added.
The proximity of fresh produce fields to farm animals has long been a concern to agricultural and health authorities, Brackett said, and is a matter that officials will continue to scrutinize. "One thing we may learn is perhaps what the minimum distance might be, but there are a lot of other considerations," he said.
The ranch in question had apparently been lacking in some so-called "good agricultural practices," including some related to the proximity issue, Reilly said. "We did find some areas of concern, the potential for problems," he confirmed.
Health officials initially narrowed the source of the E. coli outbreak to one processor, Natural Selection Foods, in San Juan Bautista, Calif.
On Sept. 15, Natural Selection Foods recalled all of its spinach products with use-by dates of Aug. 17 to Oct. 1. Four other distributors, all of whom got spinach from Natural Selection, also recalled their products.
Natural Selection processes fresh spinach for more than two dozen brands, including Earthbound Farm, Dole and Ready Pac.
Earlier this month, the U.S. Food and Drug Administration said consumers could resume eating fresh spinach.
For the latest E. coli updates, visit the CDC.