Listeriosis is an infection caused by the bacteria Listeria monocytogenes. There are about 11 to 29 cases of listeriosis reported, with 1 to 9 deaths each year in Washington. Listeriosis can cause mild, flu-like symptoms or intestinal illness to severe invasive illness, including bloodstream infections (sepsis) and meningitis.
Symptoms of Listeriosis
Listeriosis symptoms vary from person to person. Common symptoms of listeriosis include fever, muscle aches, diarrhea, and an upset stomach. These mild illnesses are generally not diagnosed. More serious infections can cause severe headache, stiff neck, confusion, loss of balance, or seizures.
Pregnant people usually have only mild, flu-like symptoms. But the infection can cause miscarriage, premature delivery, or stillbirth.
About 30-50 percent of infants who are infected with listeriosis prenatally die, as well as over 60 percent of infected adults aged 60 years or older.
How People Get Listeriosis
The most common way to get listeriosis is by eating food contaminated with Listeria. People who are infected during pregnancy can pass Listeria to their fetus or newborn baby.
Anyone who is exposed to Listeria bacteria can get listeriosis. Pregnant people, newborns, older adults, and people with weakened immune systems are at higher risk for serious infection.
How to Prevent Listeriosis
General Recommendations
- Avoid unpasteurized (raw) milk or products made from unpasteurized milk.
- Thoroughly cook raw meat, such as beef, pork, or poultry.
- Wash raw fruits and vegetables thoroughly before eating.
- Keep uncooked meats separate from vegetables, cooked foods, and ready-to-eat foods.
- Wash hands, knives, cutting boards, and counters after handling uncooked foods, such as raw meat or raw produce.
- Eat perishable and ready-to-eat foods (like deli items) as soon as possible. Follow storage instructions.
For Those at High Risk
Pregnant people, older adults, and people with weakened immune systems, should avoid:
- All soft cheeses (including Mexican-style cheeses like queso blanco, queso fresco, Panela, blue cheeses, Brie, Camembert, and feta) unless the label says they are made from pasteurized milk.
- Hot dogs, lunch meats, or deli meats, unless they are heated to be steaming hot. Avoid getting fluid from hot dogs or deli meat packages on other foods, utensils, and food preparation surfaces. Wash your hands after handling hot dogs, luncheon meats, and deli meats.
- Refrigerated pâtés or meat spreads. It is safe to eat canned or shelf-stable* pâtés and meat spreads.
- Cold-smoked fish, such as salmon, trout, or mackerel, unless it’s in a cooked dish, like a casserole. These products are often labeled "nova-style," "lox," "smoked," or "jerky" and are sold in the refrigerated section or at deli counters. It is safe to eat smoked fish that comes in a can or shelf-stable* package.
- Leftovers or ready-to-eat foods from deli counters, unless they are heated or reheated to be steaming hot before eating.
*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 (such as vacuum sealing, irradiation, freeze drying).
Treatment for Listeriosis
Severe infections are treated with antibiotics. Talk to a health care provider if you are concerned about symptoms of listeriosis.