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2009 E. Coli Outbreak Serves as a Reminder of Risks of Eating Raw Cookie Dough

Dec. 9, 2011 -- Raw cookie dough, whether it's homemade or store-bought, should be destined for your oven, not your mouth.

That's one of the CDC's top lessons from the 2009 E. coli O157:H7 outbreak in refrigerated Nestle Toll House cookie dough products.

During the outbreak, 77 people in 30 states became ill after eating the dough before baking it. Of these, 35 people were hospitalized. The outbreak prompted a recall of 3.6 million packages of cookie dough and some changes in the way that Nestle and other companies manufacture their cookie dough.

That was the first time an E. coli outbreak was traced to ready-to-bake commercial prepackaged cookie dough. The details of the outbreak and the steps taken to control it appear in the journal Clinical Infectious Diseases.

How the Cookie Crumbles

The issue is much larger than one brand, says the CDC's Karen Neil, MD, MSPH. “You shouldn’t eat raw cookie dough, regardless of who makes it,” she says.

The same goes for any product that is supposed to be cooked or baked, including cake and biscuit batter. “Raw cookie dough is not ready to eat, it is ready to bake,” Neil says.

Other cookie dough products, such as cookie dough-flavored ice cream and cookie dough bites, are likely treated in a way that makes them safe to eat, Neil says.

As part of their investigation into the 2009 E. coli outbreak, researchers searched for the source of the contamination but were unable to pinpoint the culprit.

“We do think that one of the more likely ways is through a contaminated ingredient,” Neil says. “We suspect flour, because flour doesn’t go through specific processes to kill pathogens.”

That has changed at Nestle and some other companies.

The days, weeks, and months after the outbreak were "very intense," says Nestle spokeswoman Roz O’Hearn. "We worked very closely with the CDC and FDA. We made a responsive decision to switch to heat-treated flour in January 2010, and continue it use it.” Several other cookie dough makers have told the FDA that they have also switched to heat-treated flour.

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