- What is listeriosis?
- How do you get listeriosis?
- What are the symptoms of listeriosis?
- Who is at risk for getting listeriosis?
- Are there tests for Listeria?
- Is there treatment for listeriosis?
- How can you reduce the risk for listeriosis?
Listeriosis is caused by the bacterium Listeria monocytogenes. The disease affects primarily the fetus of pregnant women, newborns, and adults with weakened immune systems. Healthy adults and children occasionally get infected with Listeria, but they rarely become seriously ill. It is not contagious from one person to another.
You get listeriosis by eating or drinking contaminated food. Listeria monocytogenes is found in soil and water. Vegetables can become contaminated from the soil or from manure used as fertilizer. Animals can carry the bacterium without appearing ill and can contaminate foods of animal origin such as meat and dairy products. Unpasteurized (raw) milk or foods made from unpasteurized milk may also contain the bacterium. The bacterium has been found in a variety of raw foods, such as uncooked meats and vegetables, as well as processed foods, like hot dogs, that become contaminated after processing. If pregnant women eat contaminated food during pregnancy, their babies can be born with listeriosis.
A person with listeriosis usually has a fever, muscle aches, and sometimes gastrointestinal symptoms, such as nausea or diarrhea. Headache, stiff neck, confusion, loss of balance, or convulsions may occur if the infection has spread to the nervous system. Once a person is exposed to the bacterium, it can take from three to 70 days for a person to actually become sick. The average is 31 days.
Fetuses and the elderly are at greatest risk for listeriosis. People with weakened
immune systems are also at an increased risk. Healthy adults and children who eat contaminated foods may not become ill or they may get a mild gastroenteritis.
If you have symptoms such as those described above, and are concerned about a possible exposure, talk to your doctor. A blood or spinal fluid test will confirm the diagnosis.
For most Listeria infections, 10 to 14 days of antibiotic therapy is usually satisfactory. When infection occurs during pregnancy, antibiotics given promptly to the pregnant woman can often prevent infection of the fetus or newborn. Babies with listeriosis receive the same antibiotics as adults, although a combination of antibiotics is often used until physicians are certain of the diagnosis. Even with prompt treatment, some infections may result in death.
- Thoroughly cook raw food from animal sources, such as beef, pork, or poultry.
- Wash raw vegetables thoroughly before eating.
- Avoid raw (unpasteurized) milk or foods made from raw milk.
- Cook until steaming hot ready-to-eat foods such as hot dogs.
- Heat deli cold cuts before eating.
- Keep uncooked meats separate from other items in the refrigerator.
- Wash hands, knives, and cutting boards with soap and hot water after handling uncooked foods.
In addition, people at high risk for complications from listeriosis, such as pregnant women and people with compromised immune systems, should
- Avoid soft cheeses, such as feta, Brie, Camembert, blue-veined, and Mexican-style cheese.
- Although the risk for listeriosis associated with foods from deli counters is low, pregnant women and people with compromised immune systems may choose to avoid these foods or thoroughly heat cold cuts before eating.
NOTE: Hard cheeses, processed cheeses, cream cheese, cottage cheese, or yogurt need not be avoided.
For more information
Division of Epidemiology and Disease Prevention
P.O. Box 70, Burlington, VT 05402
863-7240 or 1-800-640-4374 toll-free