Dole "has recently been contacted" by authorities regarding the outbreak, which involved packaged salad produced in its Springfield, Ohio, facility, company officials told the Journal, noting that the company is cooperating with the investigation.
The Justice Department declined comment.
This week, company officials in Springfield said limited production has restarted at the facility and will expand in the coming weeks.
The outbreak affected the health of 19 people in the U.S. and 14 people in Canada, according to the Centers for Disease Control and Prevention. Among the 19 in the U.S., one man in Michigan died.
Three people died in Canada, although it has not been determined if listeria contributed to the cause of those deaths, the Canadian Public Health Agency has said.
The U.S. Food and Drug Administration is still investigating how the products may have become contaminated.
Company officials in Springfield said production at their site will continue to ramp up in the coming weeks.
According to the Journal, a government report reviewed by that news organization showed that the company had evidence of potentially dangerous bacteria in its Ohio salad plant more than a year before the company withdrew its packaged salads from grocery stores.
Samples taken by Dole in its Springfield plant tested positive for the bacteria as early as July 2014, according to an inspection report by the U.S. Food and Drug Administration. Federal inspectors also found the company failed to adequately test its plant for potentially dangerous bugs.
The FDA reports "deal with issues at our plant that we have corrected," William Goldfield, a spokesman for Dole, told the Journal. "We have been working in collaboration with the FDA and other authorities to implement ongoing improved testing, sanitation and procedure enhancements, which have resulted in the recent reopening of our Springfield salad plant."
The FDA confirmed the report and said the agency initiates inspections when it becomes aware of information indicating an immediate public health threat.
Federal investigators said Dole didn't test surfaces at the Springfield plant that came into contact with food. Moreover, Dole conducted testing elsewhere in the plant prior to food production and before sanitization.
Food safety experts said this method may have made finding listeria less likely or made it tough to know whether sanitization procedures had been effective, according to the Journal.
Listeria is a food-borne bacteria typically found in raw vegetables and meats, as well as some soft cheeses. About 1,600 illnesses and 260 deaths due to listeriosis occur annually in the U.S., according to the CDC.
In January, Dole officials voluntarily recalled all Dole Brand and private-label packaged salads produced at the site. It also temporarily closed the facility during the investigation.
The recalled products included several brands and varieties of salad mixes throughout the Eastern U.S. and Eastern Canada. The products were identified by the letter "A" at the beginning of the manufacturing code on the packages.
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