What is listeriosis?

Listeriosis is an infection caused by the bacteria Listeria monocytogenes. There are about ten to 25 cases of listeriosis reported each year in Washington. Listeriosis can cause a mild, flu-like illness or a serious infection of the bloodstream or the lining covering the brain and spinal cord.

How is listeriosis spread?

The most common way to get listeriosis is by eating food contaminated with Listeria. Women who are infected during pregnancy can pass Listeria to their fetus or newborn baby.

Who gets listeriosis?

Anyone who is exposed to Listeria bacteria can get listeriosis. Pregnant women, newborns, elderly adults, and people with weakened immune systems are at increased risk for serious infection.

What are the symptoms of listeriosis?

Usual symptoms of listeriosis include fever, muscle aches, diarrhea, and an upset stomach. Mild illnesses are generally not diagnosed. More serious infections cause severe headache, stiff neck, confusion, loss of balance, or convulsions. Although pregnant women often have a mild, flu-like illness, listeriosis can cause miscarriages, premature births or still-births.

About 30-50 percent of newborns and 35 percent of nonpregnant adults with serious infection die from listeriosis.

How soon after infection do symptoms appear?

Symptoms can appear from three to 70 days after exposure. About half of infected people have symptoms within three weeks.

How is listeriosis diagnosed?

Serious infections with listeriosis are diagnosed by testing a sample taken from body tissues, such as blood or cerebrospinal fluid (CSF).

How is listeriosis treated?

Antibiotics are used to treat listeriosis.

What can I do to prevent listeriosis?

  • General recommendations:

    • Avoid unpasteurized (raw) milk or foods made from unpasteurized milk.
    • Thoroughly cook raw meat, 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.
    • Wash hands, knives, and cutting boards after handling uncooked foods.
    • Eat perishable and ready-to-eat foods as soon as possible.
  • Additional recommendations for those at high risk, such as pregnant women, elderly adults, and persons with weakened immune systems:

    Avoid the following foods:

    • All soft cheeses (including Mexican-style cheeses such as queso blanco, queso fresco, and Panela, blue cheeses, Brie, Camembert and feta) unless their label states they are made from pasteurized milk.
    • Hot dogs, lunch meats or deli meats, unless they are reheated until steaming hot.
    • Refrigerated pâtés or meat spreads. It is safe to eat canned or shelf-stable* pâtés and meat spreads.
    • Refrigerated smoked seafood, unless it is in a cooked dish, such as a casserole. Refrigerated smoked seafood, such as salmon, trout, whitefish, cod, tuna or mackerel, is most often labeled as "nova-style," "lox," "kippered," "smoked," or "jerky". The fish is found in the refrigerator section or sold at deli counters of grocery stores and delicatessens. It is safe to eat canned or shelf-stable* smoked seafood.
    • Leftover foods or ready-to-eat foods from delicatessen counters, unless heated/reheated to steaming hot before eating.
    • Avoid getting fluid from hot dog packages on other foods, utensils, and food preparation surfaces. Wash your hands after handling hot dogs, luncheon meats, and deli meats.

* "Shelf-stable" refers to a food that is typically refrigerated but has been altered to be safely stored in a sealed container at room temperature (e.g., vacuum sealing, irradiation, freeze drying).