About Listeriosis - Minnesota Dept. of Health

About Listeriosis

Listeriosis is a rare, but serious infection caused by eating food contaminated with the bacterium Listeria monocytogenes. The disease affects primarily pregnant women and their newborns, older adults, and adults with weakened immune systems. In Minnesota, 4 to 19 cases of listeriosis are reported per year.

On this page:
Fact Sheet
High Risk
Incubation Period

Fact Sheet

High Risk

  • Groups at high risk for invasive listeriosis:
    • Pregnant women and their newborns
    • Older adults
    • Individuals with weakened immune systems


  • People who are not in the high risk groups usually have no symptoms at all.

  • Older adults and those with weakened immune systems may develop an infection of the blood. Symptoms include:
    • fever
    • muscle aches
    • nausea
    • diarrhea
  • If infection spreads to the nervous system, other symptoms may include:
    • headache
    • stiff neck
    • confusion
    • loss of balance
    • convulsions
  • Infected pregnant women may experience only a mild, flu-like illness; however, infections during pregnancy can lead to miscarriage or stillbirth, premature delivery, or infection of the newborn.

Incubation Period

  • Symptoms usually begin from 3 to 70 days after consuming the bacteria.


  • Infection occurs after the bacteria are ingested.
  • Listeria monocytogenes are bacteria that can naturally be found in the environment, soil, and animals.
  • The bacteria can be found in a variety of raw foods, such as uncooked meats and vegetables.
  • Processed foods may also become contaminated with Listeria after processing; soft cheeses, hot dogs, and cold cuts or deli meats.
  • Unpasteurized (raw) milk or foods made from unpasteurized milk may contain Listeria.


Listeria monocytogenes is a bacterium that can naturally be found in the environment, soil, and animals. When the bacteria get onto food or other surfaces and then into your mouth, they can make you sick. Listeria illness is rare, but people in high risk groups need to be especially cautious to avoid foods and activities that have the highest risk for causing a Listeria infection.

Avoid certain foods if you are in a high risk group

  • Avoid unpasteurized beverages or foods. Drink only pasteurized milk, juice, or cider. Avoid foods made from unpasteurized milk.
  • Do not eat hot dogs, luncheon meats, or deli meats, unless they are reheated until steaming hot. Avoid cross-contaminating other foods, utensils, and food preparation surfaces with fluid from hot dog packages, and wash hands after handling hot dogs, luncheon meats, and deli meats.
  • Do not eat soft cheeses such as feta, Brie, Camembert, blue-veined cheeses, and Mexican-style cheeses such as "queso blanco fresco." Cheeses that may be eaten include hard cheeses; semi-soft cheeses such as mozzarella; pasteurized processed cheese slices and spreads; cream cheese; and cottage cheese.
  • Do not eat refrigerated pâtés or meat spreads. Canned or shelf-stable pâtés and meat spreads may be eaten.
  • Do not eat refrigerated smoked seafood, unless it is contained in a cooked dish, such as a casserole.
  • CDC: Listeria and Food
    Find more recommendations from the Centers for Disease Control and Prevention.

Wash your hands

  • Wash your hands after handling raw meats.
  • Always wash hands after contact with farm animals, pets, animal feces, and animal environments.
  • Wash hands after using the bathroom and changing diapers, and before handling or eating any food.
  • Hand Hygiene
    More information about washing your hands.

Keep your food preparation areas clean

  • Never place cooked meat or poultry on the unwashed plate that held the raw product.
  • Wash raw fruits and vegetables before eating.
  • Keep raw meat and poultry separate from produce and other foods when shopping for and storing groceries.
  • Wash hands, cutting boards, countertops, cutlery, and utensils after touching raw poultry or meat.

Chill, use food quickly, and clean

Be careful when dealing with animals

  • Always wash hands after contact with farm animals, pets, animal feces, and animal environments.

More information

Updated Tuesday, 29-Jan-2019 16:19:53 CST