Prosecutors are examining whether company executives committed wrongdoing in their handling of the outbreak.
Blue Bell Creameries has not responded to CNN's request for comment.
After weeks of gradual recalls, Blue Bell recalled
all its ice cream, frozen yogurt, sherbet and other frozen treats sold in 23 states on April, 20, 2015, after it said listeria was found on the lid of a food service cup
the month before. However, an investigation by the Centers for Disease Control and Prevention showed the listeria outbreak dated back to 2010.
The agency connected patients from 2010-2015 to the current outbreak through comparisons to a database of bacteria DNA
The origin of the strain was then unknown, but "the fact that it was the same strain over the last five years suggests it could have lurked somewhere in the factory the whole time," Dr. Robert Tauxe, deputy director of the CDC Division of Foodborne, Waterborne and Environmental Diseases, told CNN last April
Listeriosis is a potentially fatal infection caused by the germ listeria
, which is found in soil, water and some animals such as poultry and cattle, including raw milk. It's especially dangerous because, unlike many other germs, it can grow in the cold temperature of a refrigerator or a food processing plant.
The CDC says older adults, pregnant women, newborns and those with weakened immune systems are most at risk. Pregnant women present with fever, fatigue and body aches, but infection can lead to miscarriage and premature delivery, as well as life threatening problems in the newborn, including stillbirth.
In milder cases, symptoms can range from stiff neck and weakness to fever, vomiting and diarrhea. In older adults and those with compromised immune systems, those symptoms can develop into meningitis
or a serious infection of the blood called septicemia
Blue Bell recently announced plans
to continue its market reentry by filling stores with Blue Bell ice cream products in Tennessee, Alabama, Georgia, and Florida, among others, beginning January 18. The company has been reintroducing products
since August 2015 in Oklahoma and Texas.
The Food and Drug Administration estimates that every year, 48 million people -- one out of six Americans -- suffer from food-borne illnesses
. More than 128,000 people are hospitalized and about 3,000 die from infections the federal government says are largely preventable.
In September 2015, the CEO of the now-defunct Peanut Corporation of America, Stewart Parnell, was sentenced to 28 years for his role in covering up a 2008 salmonella outbreak that killed nine and infected another 714 people across 46 states. Prosecutors were able to prove that Parnell knew that he was selling salmonella-tainted peanut butter paste; the outbreak resulted in one of the largest food recalls in American history.