LISTERIOSIS

South Dakota Department of Health

Office of Disease Prevention - 605-773-3737 — (1-800-592-1861 in South Dakota only)

This material is provided for informational purposes only and is not a substitute
for medical care. We are not able to answer personal medical questions. Please see your
health care provider concerning appropriate care, treatment or other medical advice.

What is listeriosis?

Listeriosis is a disease caused by eating food contaminated with the bacterium Listeria monocytogenes.

Who is at greatest risk of getting listeriosis?

Pregnant women and their unborn babies,
Persons with weakened immune systems, such a those with AIDS,
Persons with cancer, diabetes, kidney disease or undergoing graft suppression therapy,
Persons who take glucocorticosteroid medications,
The elderly.

Healthy adults and children occasionally get infected with Listeria, but they rarely become seriously ill.

How do you get listeriosis?

You get listeriosis by eating food contaminated with Listeria. Babies can be born with listeriosis if their mothers eat contaminated food during pregnancy.

What are the symptoms of listeriosis?

A person with listeriosis may have fever, muscle aches, and sometimes nausea or diarrhea. If infection spreads to the nervous system, headache, stiff neck, confusion, loss of balance, or convulsions can occur.

Pregnant women may experience a mild, flu-like illness; however, infections during pregnancy can lead to premature delivery, infection of the newborn, or even stillbirth.

How does Listeria get into food?

Listeria monocytogenes is widely distributed in nature. Vegetables can become contaminated from the soil or from manure used as fertilizer. Animals can carry the bacterium and can contaminate meat and dairy products. Listeria has been found in a variety of raw foods, such as uncooked meats and vegetables, as well as in processed foods, such as soft cheeses and cold cuts. Unpasteurized milk or foods made from unpasteurized milk may contain the bacterium. Listeria can grow at refrigerator temperatures.

Can listeriosis be prevented?

Yes, recommendations to reduce your risk for listeriosis include:

Cook raw food from animal sources (e.g., beef, pork, or poultry) thoroughly.
Wash raw vegetables thoroughly before eating.
Keep uncooked meats separate from vegetables and from cooked foods and ready-to-eat foods.
Avoid unpasteurized milk or foods made from raw milk.
Wash hands, knives, and cutting boards after each handling of uncooked foods.
Keep your refrigerator clean; keep the temperature between 34-40 degrees F.

In addition, persons at high risk for complications from listeriosis (i.e., pregnant women and immunocompromised persons) should:

Avoid soft cheeses (i.e., feta, Brie, Camembert, blue-veined, and Mexican-style cheese). There is no need to avoid hard cheeses, processed cheeses, or cottage cheese.
Cook leftover foods or ready-to-eat foods (e.g., hot dogs) until steaming hot.
Although the risk for listeriosis associated with foods from deli counters is low, pregnant women and immunocompromised persons may avoid these foods or thoroughly reheat cold cuts before eating.

Dietary Recommendations for People at Higher Risk of Listeriosis*

1. Foods to avoid include:

Raw or unpasteurized milk, including goat milk.
Soft cheeses (eg, feta, goat, Brie, Camembert, Gorgonzola, blue-veined, and Mexican-style queso fresco cheese).
Dairy products that contain unpasteurized milk.
Foods from delicatessen counters (eg, prepared salads, meats, cheeses) that have not been heated/reheated adequately.
Refrigerated pâtés, other meat spreads, and refrigerated, smoked seafood that have not been heated/reheated adequately.

2. Ways to reduce risk include:

Cook leftover or ready-to-eat foods (eg, hot dogs) until steaming hot before eating (165°F).
Wash raw vegetables.
Wash hands, knives, utensils, and cutting boards after exposure to uncooked or ready-to-eat foods.
Prevent contamination from fluids of uncooked meats, hot dogs, and packaging onto other foods or food preparation surfaces by keeping them separate from vegetables, uncooked foods, and ready-to-eat foods.
Use a refrigerator thermometer to set the refrigerator temperature to 40°F or lower and the freezer temperature to 0°F or lower.

*Pregnant women, older adults, and people who are immunocompromised by illness or therapy are at higher risk of invasive listeriosis.

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