Source of 2006 Spinach E. coli Outbreak a Mystery: FDA

ByABC News
March 23, 2008, 11:16 PM

Mar. 23 -- FRIDAY, March 23 (HealthDay News) -- After months of research, U.S. and California health investigators have narrowed the source of last fall's deadly nationwide spinach-borne E. coli outbreak to produce grown in one California field.

But the exact source of the bacteria, which sickened 205 people and killed three, may never be known, health officials have concluded.

"Potential environmental risk factors for E. coli O157:H7 contamination at or near the field [in San Benito County] included the presence of wild pigs, the proximity of irrigation wells used to grow produce for ready-to-eat packaging, and surface waterways exposed to feces from cattle and wildlife," according to a report released Friday by the U.S. Food and Drug Administration, which oversaw the investigation.

"Because the contamination occurred before the start of the investigation, and because of the many ways that E. coli O157:H7 can be transferred -- including animals, humans, and water -- the precise means by which the bacteria spread to the spinach remain unknown," the report concluded.

Beginning early last September, health officials began to receive reports of gastrointestinal sickness after consumption of bagged fresh spinach. 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.

The outbreak caused consumers to shun fresh spinach for nearly a month, and the FDA only advised consumers to resume eating the produce again in early October.

Tracing the exact cause of food-borne illness is always tricky, experts said.

Speaking at the height of the outbreak last fall, Dr. Pascal James Imperato, chairman of the department of preventive medicine and community health at SUNY (State University of New York) Downstate Medical Center in New York City, said, "It may very well be that we may never be able to determine whether this occurred in the processing or the growing of spinach."