The investigation into the Oklahoma facility found food contact equipment used in processing and packaging was stored in the basement—a hot and humid area—uncovered and unprotected from condensate that would drip onto surfaces.

In the report, Blue Bell said, “Preliminary evaluations indicate cleaned equipment and sealed ingredients buckets not being used in production may have become contaminated with Listeria while being stored in a small room outside our sanitary production area. Our investigation indicated it was possible that atomized particles potentially carrying Listeria from time to time were released from a nearby drain in the room. If the equipment and the outside of these buckets were not cleaned successfully before being put back into the production area, they could have spread Listeria into the product through employee and equipment contact.” Blue Bell added it has stopped storing out-of-service equipment in this location and is evaluating the facility design to find an appropriate permanent home for the equipment.

Blue Bell pulled all its products from store shelves in April after an outbreak of Listeriosis was linked to its ice cream products. Since the recall was initiated, Blue Bell has collected approximately 8 million gallons of ice cream and ice cream products. The voluntary recall included all Blue Bell ice cream, frozen yogurt, sherbet and frozen shakes. Blue Bell distributed the products to approximately 23 states in the US, including many in the South and Midwest.

The company recently pledged to “reassess everything about our operations across the company–from facility and equipment layout to employee training.”

The company is in the process of a comprehensive review of all aspects of operations at its three facilities. According to Blue Bell, because Listeria is ubiquitous in the environment, it has adopted a broadly focused remediation plan aimed at confronting any possible sources of contamination.

“We hope our efforts demonstrate the seriousness with which we are taking this situation, as well as our commitment to making sure we get this right,” says Paul Kruse, company CEO. “We are committed to seeing this plan through and to working with the FDA each step of the way. Once Blue Bell, the FDA and the applicable state regulators agree we are ready to reintroduce products into commerce, we plan to resume production with a phased-in selection of flavors and sizes, expanding only after our revised programs have demonstrated they are capable of ensuring product safety.”

 Authorities at CDC say 10 people with Listeriosis related to this outbreak have been confirmed in four states. Five individuals were patients treated at a single hospital in Kansas who were served ice cream from Blue Bell’s single-serving products and milkshakes made from these products. Three deaths also have been reported. Listeriosis did not cause the deaths, though it may have been a contributing factor, according to Kansas health officials.