AUSTIN, Texas — Texas-based Blue Bell Creameries had a Listeria problem at its Oklahoma plant as early as 2013 and did not do enough to make sure its factory was sanitized, according to documents from the U.S. Food and Drug Administration.

The documents released on Thursday and based on inspections in March and April of this year said there were presumptive positive tests as early as March 2013 for Listeria on surfaces at the company’s Broken Arrow, Oklahoma, plant in places such as a floor in front of freezers.

“You failed to demonstrate your cleaning and sanitizing program is effective in controlling recurring microbiological contaminations,” the report said.

In April, the 108-year-old company, based in Brenham, announced a voluntary recall of its products. Health officials had said three people made ill by Listeria between January 2014 and January 2015 had died in a Kansas hospital where Blue Bell frozen treats were served.

Swab tests showed the presence of Listeria on non-food surfaces at the Oklahoma plant, said Joe Robertson, a Blue Bell spokesman.

Company protocol at the time was to clean and sanitize the area and if a negative result came back, the plant could go back into operation, he said.

“We see now that the protocol was probably inadequate at the time,” he said.

The company is reevaluating its entire operations and is looking to return its products to store shelves soon.

The FDA also reported problems at Blue Bell plants in Sylacauga, Alabama, and Brenham, Texas.

The U.S. Centers for Disease Control and Prevention said Listeria monocytogenes are organisms that can cause serious infection and can be deadly for newborns, elderly people and those with weak immune systems.

Healthy people may suffer short-term symptoms such as high fever, nausea, abdominal pain and diarrhea.