Listeriosis (Listeria monocytogenes)
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Infectious Disease Epidemiology, Prevention and Control Division
651-201-5414
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.
For more information:
On this page:
Fact sheet
High risk
Symptoms and incubation period
Transmission
Prevention
Fact sheet
- Listeriosis Fact Sheet
Printable Listeriosis fact sheet.
High risk
- Groups at high risk for invasive listeriosis:
- Pregnant women and their newborns
- Adults aged 65 years and older
- Individuals with weakened immune systems
- Other people can be infected with Listeria, but they rarely become seriously ill.
Symptoms and incubation period
- Invasive means bacteria have spread beyond the intestines (gut). Invasive listeriosis happens when Listeria have spread beyond the intestines.
- Symptoms of invasive illness usually start within 2 weeks after eating food contaminated with Listeria.
Symptoms of invasive illness
People who are pregnant
Symptoms typically include:
- Flu-like symptoms, such as
muscle aches and fatigue
People who are not pregnant
Symptoms typically include:
- Fever
- Flu-like symptoms, such as
muscle aches and fatigue - Headache
- Stiff neck
- Confusion
- Loss of balance
- Seizures
Severity of invasive illness
People who are pregnant
Symptoms in pregnant people are usually mild. Some pregnant people never have symptoms.
However, infection during pregnancy usually leads to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.
People who are not pregnant
Symptoms in non-pregnant people can be severe.
Almost 1 in 20 non-pregnant people with invasive listeriosis die.
Transmission
- 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.
- Unpasteurized (raw) milk or foods made from unpasteurized milk may contain Listeria.
Prevention
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.
Choose Safer Foods
Listeria is especially harmful for some people:
- Older adults (65 and older)
- People who have weakened immune systems (have health problems or take medicines that lower the body's ability to fight germs and sickness)
- Pregnant people and newborns
If you are in any of these groups, choose safer foods to protect your health or your pregnancy:
| Do Not Eat | Choose These Instead |
|---|---|
| Unpasteurized soft cheeses, such as queso fresco and brie Unheated cheeses sliced at a deli | Hard cheeses, such as cheddar and parmesan Cottage cheese, cream cheese, string cheese, feta, and mozzarella Pasteurized soft cheeses heated to an internal temperature of 165°F or until steaming hot Deli-sliced cheeses heated to 165°F or until steaming hot |
| Unheated deli meat, cold cuts, hot dogs, and fermented or dry sausages | Deli meat, cold cuts, hot dogs, and fermented or dry sausages reheated to 165°F or until steaming hot |
| Premade deli salads, such as coleslaw and potato, tuna, or chicken salad | Homemade deli salads |
| Refrigerated pâté or meat spreads | Pâté or meat spreads in sealed, airtight containers that don’t need to be kept refrigerated before opening |
| Refrigerated smoked fish | Smoked fish in sealed, airtight packages or containers that don’t need to be kept refrigerated before opening Smoked fish cooked in a casserole or other cooked dishes |
| Raw or lightly cooked sprouts | Sprouts cooked until steaming hot |
| Cut melon left out for more than 2 hours (1 hour if it’s exposed to temperatures hotter than 90°F, such as a picnic or hot car) Cut melon in refrigerator for more than a week | Melon that has just been cut |
| Raw (unpasteurized) milk, yogurt, and ice cream | Pasteurized milk, yogurt, and ice cream |
Check for recalled foods and do not eat them
- Check for foods recalled for Listeria contamination: Foodsafety: Recalls and Outbreaks
- Throw out any recalled food items and clean your refrigerator: CDC: Cleaning Your Refrigerator Because of a Food Recall
Contact a healthcare provider
- Older adults and people with weakened immune systems
- Call a healthcare provider right away if you have a fever and feel more tired and achy than normal. You may also have a headache, stiff neck, confusion, loss of balance, or seizures if you have Listeria. Early treatment can help save your life.
- Pregnant people
- Call a healthcare provider right away if you have a fever and feel more tired and achy than normal. Let them know if you ate a recalled food in the past two months or are worried about something you ate. (This is because Listeria illness can sometimes start many weeks later.) Early treatment can help save your baby.
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.
Use safe food preparation practices
- CDC: About Four Steps to Food Safety
Follow these recommendations from CDC to reduce the risks of foodborne Listeria infection.
More information
Last Updated: 07/12/2024