General Mills Inc. has initiated a nationwide recall of three brands of flour, totaling about 10 million pounds, in response to a 20-state E. coli outbreak that has sickened 38 people.

Although government officials have reportedly been investigating the outbreak, no state or federal agencies had released any information about it at the point Tuesday when the Minneapolis-based company announced the recall.

These are three of several varieties and brands of flour recalled by General Mills in relation to a multi-state outbreak of E. coli.

“State and federal authorities have been researching 38 occurrences of illnesses across 20 states related to a specific type of E. coli O121, between Dec.21, 2015, and May 3, 2016,” according to a news release from General Mills.

“While attempting to track the cause of the illness, CDC (Centers for Disease Control and Prevention) found that approximately half of the individuals reported making something homemade with flour at some point prior to becoming ill. Some reported using a General Mills brand of flour.”

The recall includes six SKUs (stock keeping units or UPC codes) of Gold Medal branded flour, two SKU’s of Signature Kitchens branded flour and one SKU of Gold Medal Wondra branded flour.

Retailers that received shipments of the recalled flour include Safeway, Albertsons, Jewel, Shaws, Vons, United, Randalls, and Acme.

“To date, E. coli O121 has not been found in any General Mills flour products or in the flour manufacturing facility, and the company has not been contacted directly by any consumer reporting confirmed illnesses related to these products,” according to the news release.

“As a leading provider of flour for 150 years, we felt it was important to not only recall the product and replace it for consumers if there was any doubt, but also to take this opportunity to remind our consumers how to safely handle flour,” Liz Nordlie, president of General Mills Baking division, said in the release.

Some of the outbreak victims may have eaten raw dough or batter. Nordlie said in the news release and a separate blog posting that no one, especially young children, should ever eat raw dough or batter because of potential pathogens.

“Consumers are reminded to not consume any raw products made with flour. Flour is an ingredient that comes from milling wheat, something grown outdoors that carries with it risks of bacteria which are rendered harmless by baking, frying or boiling,” according to the news release.

“Consumers are reminded to wash their hands, work surfaces, and utensils thoroughly after contact with raw dough products or flour, and to never eat raw dough or batter.”

The recalled flour can be identified by the following label information:

  • 5-ounce Gold Medal Wondra — Package UPC 000-16000-18980; Better if Used by Dates 25FEB2017 thru 30MAR2017
  • 2-pound Gold Medal All Purpose Flour — Package UPC 000-16000-10710; Better if Used by Dates 25MAY2017KC thru 03JUN2017K
  • 5-pound Gold Medal All Purpose Flour — Package UPC 000-16000-10610; Better if Used by Dates 25MAY2017KC, 27MAY2017KC thru 31MAY2017KC, 01JUN2017KC, 03JUN2017KC thru 05JUN2017KC, 11JUN2017KC thru 14JUN2017KC
  • 10-pound Gold Medal All Purpose Flour — Package UPC 000-16000-10410; Better if Used by Dates 02JUN2017KC,03JUN2017KC
  • 10-pound Gold Medal All Purpose Flour Banded Pack — Package UPC 000-16000-10410; Better if Used by Dates 03JUN2017KC, 04JUN2017KC, 05JUN2017KC
  • 5-pound Gold Medal Unbleached Flour — Package UPC 000-16000-19610; Better if Used by Dates 25MAY2017KC, 27MAY2017KC, 03JUN2017KC, 04JUN2017KC
  • 5-pound Signature Kitchens All Purpose Flour Enriched Bleached — Package UPC 000-21130-53001; Better if Used by Dates BB MAY 28 2017
  • 5-pound Signature Kitchens Unbleached Flour All Purpose Enriched —Package UPC 000-21130-53022; Better if Used by Dates BB MAY 27 2017
  • 2-pound Gold Medal Self Rising Flour — Package UPC 000-16000-11710; Better if Used by Dates 23AUG2016KC

Pizza Ranch desserts containing flour dough have been linked to E. coli O157:H7 food poisonings in nine states, federal officials say. The outbreak started in December, mainly among people who’d eaten at the Iowa-based chain’s restaurants.  The CDC reports that 13 people were sickened in Illinois, Iowa, Kansas, Minnesota, North Carolina, Nebraska, New Jersey, South Dakota and Wisconsin. Minnesota. Nine of the people said they recently had eaten at Pizza Ranches.  Two children, in Kansas and Nebraska, suffered kidney failure (hemolytic uremic syndrome) and had to be hospitalized.

In an article in Clinical Infections Diseases dug a bit deeper into the Nestle Tollhouse Cookie Dough E. coli O157:H7 outbreak of 2009.  Seventy-seven patients with illnesses during the period 16 March–8 July 2009 were identified from 30 states; 35 were hospitalized, 10 developed hemolytic-uremic syndrome, and none died. Sixty-six percent of patients were <19 years; 71% were female. In the case-control study, 33 of 35 case patients (94%) consumed ready-to-bake commercial prepackaged cookie dough, compared with 4 of 36 controls (11%) (matched odds ratio = 41.3; P < .001); no other reported exposures were significantly associated with illness. Among case patients consuming cookie dough, 94% reported brand A. Three nonoutbreak STEC strains were isolated from brand A cookie dough. The investigation led to a recall of 3.6 million packages of brand A cookie dough and a product reformulation.

A more likely source of contamination is that a contaminated ingredient was used in the product. Ready-to-bake cookie dough is not a ready-to-eat food and contains several ingredients, including flour, pasteurized eggs, chocolate chips, molasses, sugar, margarine, baking soda, and vanillin/vanilla extract. The eggs used in brand A products were pasteurized, making eggs a less likely vehicle unless there was a pasteurization failure; this was not identified during the investigation. Molasses, sugar, baking soda, and margarine, which undergo pathogen kill steps during processing, were also considered less likely sources of contamination.

The possibility of contaminated chocolate chips was considered, because most patients reported consuming chocolate chip–containing varieties of brand A cookie dough. Although chocolate has never been linked to past E. coli O157 outbreaks, it has been implicated in Salmonella outbreaks, and Baylis et al, documented survival of E. coli O157 in artificially contaminated chocolate for up to 366 days. However, because chocolate chip varieties comprise the majority of cookie dough sales, it would not be unusual that chocolate chip varieties were reported by most patients. The chocolate chips that company A uses in its ready-to-bake cookie dough and the brand A chocolate chips sold to consumers for home baking are manufactured in the same facility, but there was no evidence of an E. coli O157 outbreak among consumers using these chocolate chips. Study results also support that chocolate chips were not the source of contamination: consumption of a chocolate chip variety of cookie dough was less strongly associated with illness compared with consumption of any cookie dough, whereas consumption of chocolate chips in non–cookie dough products was not significantly associated with illness. Flour, a raw agricultural product (ie, does not undergo processing to kill pathogens), was also considered as a possible source of contamination. Low levels of Salmonella contamination can occur in wheat flour, and flour and flour-based mixes have been implicated in foodborne Salmonella outbreaks. Generic E. coli species have also been found in flour; 1 US study found E. coli in 12.8% of commercial wheat flour samples examined. Although our investigation found no conclusive evidence that contaminated flour was the source of this outbreak, contaminated flour remains a prime suspect for introducing the pathogen to the product. Because flour is frequently purchased in large quantities by manufacturers for use in food products, if contaminated flour were responsible, a single purchase of contaminated flour might have been used to manufacture multiple lots and varieties of dough over a period of time. This would be consistent with UBDs on packages obtained from patients (23 June–11 August 2009), suggesting that product contamination occurred over several weeks.