What is listeriosis?
Listeriosis is a serious bacterial infection. It is usually caused by eating foods contaminated with Listeria monocytogenes. The disease primarily affects older adults, pregnant women, newborns, and adults with weakened immune systems. Rarely are persons without these risk factors affected.

Who is at risk for listeriosis?
The following groups are at increased risk:

• Pregnant women:
• Newborns: Newborns suffer the most serious effects of infection in pregnancy.
• Persons with weakened immune systems from transplants or certain diseases, therapies, or medications.
• Persons with cancer, diabetes, alcoholism, liver or kidney disease.
• Persons with AIDS:
• Older adults

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

What are the symptoms of listeriosis?
A person with listeriosis usually has fever and muscle aches, often preceded by diarrhea or other gastrointestinal symptoms. Almost everyone who is diagnosed with listeriosis has "invasive" infection. “Invasive infection” means that the bacteria spread beyond the gastrointestinal tract. The symptoms vary with the infected person:

• Pregnant women may experience only a mild, flu-like illness. However, infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.
• Persons other than pregnant women may experience the following symptoms: fever, muscle aches, headache, stiff neck, confusion, loss of balance, and convulsions.

How does Listeria get into food?
Listeria monocytogenes is found in soil and water. Animals, carrying the bacterium, may not appear ill and can contaminate foods such as meats and dairy products. The bacterium has been found in a variety of raw foods, such as uncooked meats and vegetables/fruits, as well as in foods that become contaminated after cooking or processing. These include soft cheeses, processed meats and smoked seafood. Unpasteurized (raw) milk and cheeses and other foods made from unpasteurized milk are particularly likely to contain the bacterium. Contamination may also occur after factory cooking but before packaging, as is the case with hot dogs and deli meats. When Listeria bacteria get into a food processing factory, it can live for years. And unlike most bacteria, Listeria bacteria can grow and multiply in some foods in the refrigerator.

How do you get listeriosis?
You can get listeriosis by eating foods contaminated with Listeria. Babies can be born with listeriosis if their mothers ate contaminated food during pregnancy. However, healthy persons may consume contaminated foods without becoming ill. Persons at risk can prevent Listeria infection by avoiding certain high-risk foods and by handling food properly.

Can listeriosis be prevented?
The general guidelines recommended for the prevention of listeriosis are similar to those used to help prevent other foodborne illnesses. In addition, there are specific recommendations for persons at high risk for listeriosis.

How can you reduce your risk for listeriosis?
General recommendations on how to prevent an infection with Listeria include:

• Thoroughly cook raw food from animal sources, such as beef, pork, or poultry to a safe internal temperature.
• Rinse raw vegetables/fruits thoroughly under running tap water before eating.
• Keep uncooked meats and poultry separate from vegetables/fruits and from cooked foods and ready-to-eat foods.
• Do not drink raw (unpasteurized) milk, and do not eat foods that have unpasteurized milk in them.
• Wash hands, knives, countertops, and cutting boards after handling and preparing uncooked foods.
• Consume perishable and ready-to-eat foods as soon as possible.

Recommendations to keep food safe:

• Be aware that Listeria monocytogenes can grow in foods in the refrigerator. Use an appliance thermometer, such as a refrigerator thermometer, to check the temperature inside your refrigerator. The refrigerator should be 40°F or lower and the freezer 0°F or lower.
• Clean up all spills in your refrigerator right away–especially juices from hot dog and lunch meat packages, raw meat, and raw poultry.
• Clean the inside walls and shelves of your refrigerator with hot water and liquid soap, then rinse.
• Divide leftovers into shallow containers to promote rapid, even cooling. Cover with airtight lids or enclose in plastic wrap or aluminum foil. Use leftovers within 3 to 4 days.
• Use precooked or ready-to-eat food as soon as you can. Do not store the product in the refrigerator beyond the use-by date; follow USDA refrigerator storage time guidelines:
  • Hot Dogs – store opened package no longer than 1 week and unopened package no longer than 2 weeks in the refrigerator.
  • Luncheon and Deli Meat – store factory-sealed, unopened package no longer than 2 weeks. Store opened packages and meat sliced at a local deli no longer than 3 to 5 days in the refrigerator.

How do you know if you have listeriosis?
If you develop fever and chills while pregnant or if you are very sick with fever and muscle aches or stiff neck, consult your doctor. A blood or spinal fluid test (to look for the bacteria) will show if you have listeriosis.

What should you do if you've eaten a food recalled because of Listeria contamination?
The risk of an individual person developing a Listeria infection after eating a contaminated product is very small. If you have eaten a contaminated product and do not have any symptoms, no tests or treatment are recommended, even if you are in a high-risk group. However, if you are in a high-risk group, have eaten the contaminated product, and become ill with fever or other symptoms of listeriosis, you should contact your physician immediately. Inform him or her that you were exposed to a product contaminated with Listeria.

Can listeriosis be treated?
Prompt treatment with antibiotics can cure the illness and prevent infection of the fetus. Even with prompt treatment, some Listeria infections result in death. This is particularly likely in older adults and in persons with other serious medical problems.