Vegetables can become contaminated from the soil, or from fertilizer made from manure. Dr. Nida said persons most at risk for listeriosis are pregnant women, newborns, adults with weakened immune systems, and the elderly. Most healthy adults and children who are exposed to Listeria do not become ill, or develop only a mild illness. Listeria has been found in a variety of raw foods, such as uncooked meats and vegetables. Some processed foods have become contaminated with Listeria after processing, such as soft cheeses and deli meats.
Listeria is killed by pasteurization and by thoroughly cooking raw food from animal sources.
Cook thoroughly raw beef, pork and poultry. Wash raw vegetables before eating. Wash hands, knives and cutting boards after handling uncooked foods. Consider avoiding foods from deli counters, or thoroughly reheat cold cuts before eating.