Listeria monocytogenes is commonly found in soil, stream water, sewage, plants, and food.[5] Listeria in soil can contaminate vegetables, and animals can be carriers. It has been found in uncooked meats, uncooked vegetables, fruits including cantaloupe[30] and apples,[31] pasteurized or unpasteurized milk and milk products, and processed foods. Pasteurization and sufficient cooking kill Listeria

https://en.wikipedia.org/wiki/Listeria