THURSDAY, Oct. 26, 2006 (HealthDay News) -- Health authorities are investigating whether wild boar may have played a role in the E. coli outbreak in September that sickened 204 people in 26 states and one Canadian province, and left three people dead.
In addition, they announced at a Thursday night press conference, nine samples of the bacteria found on one ranch in California's Salinas Valley match both the contaminated fresh spinach and the human "isolates" from the outbreak.
"Clearly, we have positive results on one property that are helping to refine our investigation," Dr. Kevin Reilly, deputy director of the prevention services division for the California Department of Health Services, said. "We have not closed any possibilities on three other [nearby] ranches, but the information is accumulating that our environmental findings are consistent on this one property."
The E. coli samples were found in a water sample in a creek, in the gastrointestinal tract of a wild boar on the property, and from cattle fecal specimens. None of the nine positive matches came from a nearby spinach field that was the source of the contaminated produce, Reilly said.
That leaves one significant unanswered question: How did the E. coli get from the ranch to the spinach field?
The answer may be the wild boars.
"Animals, wildlife and water were in close proximity to the field," Reilly said. "We have evidence for fences torn down, wildlife going into the actual spinach fields themselves. That's where the investigation is centered right now. There's clear evidence that the pig population has access and goes onto the fields. Is that the ultimate means of contamination or is that one potential means, including water and wildlife? We're still investigating that."
Meanwhile, officials are continuing investigations into three other ranches in the Salinas Valley. Several E. coli samples were found there, but none matched the outbreak strain when put through more advanced genetic testing.
"It is not unusual or unexpected that we would find E. coli associated with domestic cattle and/or wildlife but, to date, we have not matched it up with the outbreak strain other than on the single ranch," Reilly said.
The ranch, which authorities did not identify, included a beef cattle operation and fields where spinach and other ready-to-eat produce were grown. The proximity of fresh produce fields to farm animals has long been a concern to agricultural and health authorities.
"We're definitely concerned about the spread of organisms in fields, and that's why we're working with [the agriculture] industry to encourage them to come up with practices to prevent this kind of contamination," said Jack Guzewich, director of the emergency coordination and response staff at the U.S. Food and Drug Administration's Center for Food Safety and Applied Nutrition.
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, which processes fresh spinach for more than two dozen brands, 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.
Earlier this month, the FDA said consumers could resume eating fresh spinach.
And at the Thursday night press conference, health officials again said that fresh spinach was safe to eat.
For the latest E. coli updates, visit the U.S. Centers for Disease Control and Prevention.