The discoveries suggest ways the potentially deadly bacteria may have tainted fields and sickened more than 200. Testing is continuing.
October 27, 2006
Rong-Gong Lin II
Los Angeles Times
The same E. coli strain blamed for sickening 204 spinach eaters and killing three has now been found in creek water and in the intestines of a wild pig killed near a suspect spinach farm, California health officials said Thursday.
The findings are significant because they suggest possible ways that the virulent bacteria, E. coli O157:H7, may have spread from cow droppings onto spinach leaves processed by Natural Selection Foods in San Juan Bautista.
Officials have refused to identify the implicated farm — one of four they are focusing on — but have said it is above cattle pastures in a valley in Monterey or San Benito counties.
Wild pigs may have defecated in the field or tracked in the bacteria, said Kevin Reilly, deputy director of prevention services for the California Department of Health Services. Boar have a history of breaking through the metal fence protecting the spinach field, and investigators have found boar tracks across the cattle pasture and in the spinach field.
"There's clear evidence that wild pigs have access and do go onto the field," Reilly said. "Is that the ultimate means of contamination? Or is that one of the potential means, including water and [other] wildlife? We're still investigating that as we speak."
Another possibility is that creek water downhill and about a mile away from the spinach field somehow mingled with the well water used to irrigate the spinach fields, Reilly said.
No contaminated samples from manure, creek water or pig intestines were found on the spinach field. All were found between half a mile and a mile away.
Other factors still being considered include the use of contaminated fertilizer and poor farmworker hygiene.
Investigators are still testing samples at three other suspect farms, and trying to determine whether poor harvesting or processing practices contributed to the spread of E. coli among greens.
Authorities also want to know why the bacteria were not or could not be removed during processing, Reilly said.
The outbreak increased concern about the proximity of cattle ranching operations to fields that grow ready-to-eat vegetables, and the possibility of cross-contamination.
The E. coli O157:H7 strain lives in the intestines of healthy cattle and is present in manure. It is passed to humans when they ingest contaminated food. Produce need be contaminated with only a small amount of E. coli for a person to get sick.
Thursday's announcements built upon a major development in the investigation two weeks ago, when officials found the bacteria in fecal samples from a cattle pasture.
In years of tracking previous outbreaks, investigators had not found a matching E. coli sample in the environment near where the tainted spinach or lettuce was grown.
All nine samples containing the bacteria — seven from manure and the latest from the water and pig — come from areas near one of the four farms.
All genetically match the strain identified in the outbreak and found in bags of Dole spinach processed by Natural Selection Foods of San Juan Bautista.
In mid-September, U.S. Food and Drug Administration officials issued a sweeping recommendation against eating fresh spinach, after linking it with the outbreak.
Days later, they narrowed the source to California, and by the end of the month, lifted warnings against eating spinach.
Other than the four farms being investigated, the FDA "feels comfortable that other producers of spinach in the Central California area and elsewhere were not involved in this outbreak," said Jack Guzewich, director of the FDA food safety center's emergency coordination and response staff.