Listeriosis

What is listeriosis?

Listeriosis is a food-borne illness transmitted by bacteria in contaminated food. The listeria organism has been found in a variety of raw foods, such as uncooked meats and vegetables, as well as in processed foods that become contaminated after processing, such as soft cheeses and cold cuts at the deli counter. Unpasteurized (raw) milk or foods made from unpasteurized milk may contain the bacterium.

Infection occurs after eating a contaminated food. It is most common during the third trimester of pregnancy, and women often have flu-like symptoms, such as fever, muscle aches, and sometimes nausea or diarrhea. The fetus and newborn are at greatest risk from the infection. Listeriosis may cause infection in the amniotic membranes leading to miscarriage, stillbirth, or severe infection in a newborn. Antibiotics are used to treat the infection when it is diagnosed.

Preventing listeriosis

The Centers for Disease Control and Prevention recommends the following measures to help prevent listeriosis infection:

• Thoroughly cook raw food from animal sources, such as beef, pork, or poultry.

• Wash raw vegetables thoroughly before eating.

• Keep uncooked meats separate from vegetables and from cooked foods and ready-to-eat foods.

• Avoid raw (unpasteurized) milk or foods made from raw milk.

• Wash hands, knives, and cutting boards after handling uncooked foods.

• Avoid soft cheeses such as feta, Brie, Camembert, blue-veined, and Mexican-style cheese. (Hard cheeses, processed cheeses, cream cheese, cottage cheese, or yogurt need not be avoided.)

• Left-over foods or ready-to-eat foods, such as hot dogs, should be cooked until steaming hot before eating.

• Although the risk of listeriosis associated with foods from deli counters is relatively low, pregnant women may choose to avoid these foods or thoroughly reheat cold cuts before eating.

• Avoid refrigerated smoked seafood such as lox or salmon, and refrigerated pates and meat spreads.