Animals can carry Listeria monocytogenes in their intestines without becoming sick. As a result, the bacteria may be spread to meat and dairy products. Listeria monocytogenes is killed by cooking or by other heating methods, such as pasteurization, used to produce ready-to-eat foods. However, ready-to-eat food can become contaminated after processing within the processing plant or along the route from the plant to your plate. Outbreaks of listeriosis are associated with ready-to-eat foods such as hot dogs, luncheon meats, cold cuts, fermented or dry sausage, and other deli-style meat and poultry. In the home, Listeria monocytogenes is destroyed if ready-to-eat foods are reheated to steaming hot.
Most people will not want to do that with their ice cream.