There are several common ways to prevent Listeria. For one, avoid FAT TOM. For instance, if you are heating your food from 30 degrees - to 130 degrees (both of which listeria can't flourish easily) you would want quickly get past 93 degrees zone, where listeria grows best.
In your refrigerator, never put your uncooked or undercooked meats above your ready-to-eat foods. If any juices, that normally would be sterilized during cooking, dripped on food that you wouldn't cook, it would be easy to catch a food borne illness.