Tuesday, July 14, 2009

Wrapping Up The Nestlé Toll House Outbreak Investigation

July 14, 2009

FDA made it official yesterday evening. The agency has wrapped up its investigation into Nestlé's Toll House cookie dough manufacturing facility in Danville, Virginia. Raw cookie dough produced in the Danville plant is believed to be responsible for an outbreak of E. coli O157:H7 infections that has sickened 76 people in 31 states. Thirty-five of the victims were hospitalized, 11 with life-threatening hemolytic uremic syndrome.

After an investigation that lasted from June 18th through July 9th, no one is any the wiser as to how at least three different strains of E. coli were able to contaminate the raw cookie dough.

"Three different strains," you ask?

Yes. Three different strains of E. coli have been recovered during the course of this outbreak investigation.

  • Strain #1: A common strain of E. coli O157:H7 was isolated from all 76 outbreak victims.
  • Strain #2: A different E. coli O157:H7 was isolated by FDA from a retained sample of Toll House raw cookie dough that was analyzed as part of the federal outbreak investigation. The E. coli O157:H7-positive sample was produced on February 10, 2009 (based on package date code #9041)
  • Strain #3: E. coli O124 – a completely different strain of toxin-producing E. coli was found in a sample of cookie dough recovered from the home of two Minnesota children who were infected with the outbreak strain.

As Roy Costa pointed out in his guest article on Marler Blog two days ago, "...the finding of more than one E coli O157:H7 strain is clearly indicative of a highly contaminated environment reservoir, and this reservoir is likely in the plant or was during the outbreak."

Or, as I suggested on Saturday, "...a long-standing build-up of contaminants over time."

In an attempt to figure out how this build-up could occur, I've been combing the old inspection reports for the Danville plant that the FDA has posted on its website. The clue may be buried in this excerpt from a 2005 inspection report, which summarizes the cookie dough production process.

"Dry ingredients are weighed out in prep rooms according to recipe specifications. Ingredients are then transported in stainless steel tubs and added to one of several mixers located near the beginning of each production line. Dough is then transferred to a hopper and extruded into either a sheet or a tube (chubs). Dough then passes through a series of cooling tunnels and is either scored or stamped into different shapes depending on the production line. Rework from the cookie dough lines is collected in stainless steel drums and added back into the mixer for a subsequent batch."

"Rework" refers to dough that is left over at the end of a production run - perhaps in the extrusion equipment, in the hoppers, or after trimming away ragged edges. This dough is saved and mixed back in with a subsequent batch – along with any contamination that the reworked dough might have picked up along the way. The Nestlé employee who accompanied the FDA inspector on this particular plant visit dodged the inspector's question as to how long "rework" might be held before being folded into to a new batch of dough.

Subsequent inspection reports do not mention rework; those reports don't describe the production process in any detail. Nor does rework, alone, answer the mystery of where the contamination originated. But it could help explain how the problem may have been perpetuated.

Nestlé has completely dismantled, cleaned and disinfected its raw cookie dough production lines. The company also has changed to new suppliers for its main ingredients, and is phasing production back in on a limited basis.

FDA has remained close-mouthed on any investigations it may have carried out of Nestlé's ingredient suppliers, or whether any of these investigations are still in progress. But from the tone of the most recent FDA update, the agency will be adding this particular outbreak to its "Unsolved Mysteries" file.


  1. Too many hands are touching our food. Loblaws in Canada just had a major recall of all of its wrapped beef that was sold way back in April! It seems Canadian beef is sent to the US to be butchered (where it can be combined with American beef), then sent back to Canada to be sorted and wrapped into specific sizes. Awful risk for a major food supplier! Thank you for the info.

  2. For information, the Loblaws recall was as a result of the E. coli O157:H7-related recall of beef cuts earlier this month by JBS Swift Beef Company of Greeley, Colorado (http://efoodalert.blogspot.com/2009/07/jbs-swift-beef-company-recall-list-of.html)

  3. The part about "rework" certainly sounds disgusting. As you said, the use of "rework" doesn't explain how the E. coli strains got into the plant and the dough, but offers a possible explanation for the perpetuation of the contamination. Since some of the equipment was allegedly difficult to clean, I wonder how long contaminated cookie dough and ingredients were left on equipment. It could have been days or weeks. Yuck!

  4. What is disgusting about the "rework" part. As long as the product is handled in a sanitary manner with proper controls there is absolutely nothing about this process that would suggest it is a problem.

  5. There is nothing disgusting about rework, if it is handled correctly. Rework, if mishandled, is highly susceptible to transferring a contaminant from one batch of product to another, as has happened on several occasions, especially with meat grinding operations.


  6. That's just it, we don't know if there are or were proper controls in place. IIRC, somewhere on this blog it was noted that the eqipment at the Nestle plant was cited on an FDA inspection as not being designed to be easily cleanable or something along those lines. As a former retail food inspector, I often saw practices that were questionable not so much because they were violations of the food code--some were in fact specifically allowed by the food code--but because they required a vigilance that was usually lacking at the retail level.

    My state's food code, which is heavily based upon the FDA model code, allows some practices that are clearly for industry convenience, yet had the potential to be problematic to say the least. One practice was allowing potentially hazardous food to be out of temperature control for up to four hours. The food code required that the time be marked somehow, that any leftover food that was part of the out-of- temperature-control batch had to be discarded once the time limit had been reached, that you couldn't have eggs out for two hours one day and then two hours the next day, etc. I always thought that allowing the practice, yet putting all of those unrealistic and difficult to enforce provisos in place was too risky. I realize that others in the profession disagree.


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