Jan 12, 2007 (CIDRAP News) Investigators have tentatively linked the recent Escherichia coli O157:H7 outbreak associated with Taco John's restaurants in Iowa and Minnesota to dairy farms near lettuce fields in California, according to the Food and Drug Administration (FDA).
The outbreak strain of E coli has been genetically matched with E coli in two environmental samples gathered on dairy farms near a lettuce-growing area in California's Central Valley, the FDA said today.
The samples were from standing water on the dairy farms, but the FDA has not reached any conclusions about the source of the E coli in the samples, FDA spokeswoman Kimberly Rawlings told CIDRAP News. She said the dairy farms are "in close proximity" to lettuce fields but declined to give any details about their location.
The outbreak affected 81 people in November and December, including 47 in Iowa, 33 in Minnesota, and 1 in Wisconsin, the FDA reported. Twenty-six people were hospitalized, and two suffered hemolytic uremic syndrome, a form of kidney failure that can be fatal.
Earlier reports associated the outbreak with Taco John's restaurants in Cedar Falls, Iowa, and Albert Lea and Austin, Minn. Epidemiologic investigation pointed to iceberg lettuce as the likely source of contamination. The FDA said there is no sign that any lettuce now on the market is causing illnesses.
The agency said it is continuing its investigation to determine if and how E coli from the dairy farms contaminated lettuce.
"FDA was able to focus on specific lettuce growing regions based on the traceback from records obtained from the lettuce processor," the statement said. "The recent DNA match provides a clue as to one possible source of the contamination for the lettuce, although others may exist. It has yet to be determined how the E. coli contaminated the lettuce."
Taco John's spokesman Brian Dixon said the company had suspended purchases from the company that had supplied produce to the three restaurants involved in the outbreak, according to an Associated Press report today. Dixon said the company, based in Cheyenne, Wyo., is talking with its suppliers about more testing of irrigation water and possibly holding produce shipments for microbiologic testing.
Officials have said the Taco John's outbreak was not related to a nearly simultaneous E coli outbreak linked to Taco Bell restaurants on the East Coast, affecting people mainly in New York, New Jersey, and Pennsylvania. Epidemiologic investigation pointed to lettuce as the likeliest cause of the Taco Bell outbreak, but the E coli strains in the two outbreaks were different.
Another high-profile E coli outbreak preceded the Taco bell and Taco John's outbreaks by about 2 months. That outbreak, caused by contaminated fresh spinach from California, involved 204 cases and 3 deaths in 26 states and one Canadian province. The outbreak strain of E coli was found in cattle manure from pastures next to spinach fields in the Salinas Valley.
The FDA said it is stepping up its efforts to address produce safety and plans to hold public meetings to involve all stakeholders in identifying and implementing safety measures.
Jan 12 FDA news release
Dec 13 CIDRAP News story "Lettuce suspected in Taco Bell E coli outbreak"