FAQ - Listeriosis

Frequently Asked Questions - Listeriosis

What is Listeriosis?
Listeriosis is a potentially serious infection caused by eating food contaminated with bacteria called Listeria Monocytogenes. The extent of food contamination with Listeria Monocytogenes has been increasingly recognized in the United States. The disease is most dangerous to pregnant women, newborns, and adults with weakened immune systems. It can be avoided by following a few simple recommendations.
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How great is the risk for Listeriosis?
In the United States, an estimated 2,500 persons become seriously ill with Listeriosis each year. Of these, 500 die. Pregnant women are about 20 times more likely than other healthy adults to get Listeriosis. About one-third of Listeriosis cases occur during pregnancy. Fetuses and newborns suffer the most serious effects of infection during pregnancy. Healthy adults and children occasionally get infected with Listeria, but they rarely become seriously ill.
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How does Listeria get into 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 Listeria without appearing ill and can contaminate other foods such as meats and dairy products. Listeria has been found in a variety of raw foods, such as uncooked meats and vegetables, as well as in processed foods that become contaminated during or after processing, such as soft cheeses and cold cuts. Unpasteurized (raw) milk or foods made from unpasteurized milk may contain Listeria. Listeria are killed by pasteurization, and heating procedures used to prepare ready-to-eat processed meats should kill the bacteria; however, sometimes contamination can occur after processing.
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How do you get Listeriosis?
You get Listeriosis by eating food contaminated with Listeria bacteria. Babies can be born with Listeriosis if their mothers eat contaminated food during pregnancy. Also, although healthy persons may eat contaminated foods without becoming ill, those at increased risk for infection may get Listeriosis after eating food contaminated with even just a few bacteria. Persons at risk can prevent Listeria infection by avoiding certain high-risk foods and by handling food properly.
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How do you know if you have Listeriosis?
A person with Listeriosis usually has a fever, muscle aches, and sometimes symptoms such as nausea or diarrhea. If infection spreads, other symptoms such as headache, stiff neck, confusion, loss of balance, or seizures can occur. Infected pregnant women may experience only a mild, flu-like illness; however, infection during pregnancy can lead to premature delivery, infection of the newborn, miscarraige or even stillbirth. There is no routine screening test to know if you could get Listeriosis during pregnancy, as there is for other diseases such as rubella. If you have symptoms such as fever or a stiff neck, talk to your doctor right away. A blood test or spinal fluid test will show if you have Listeriosis. During pregnancy, a blood culture is the best way to find out if your symptoms are from Listeriosis.
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How can you reduce your risk for Listeriosis?
General recommendations: - Thoroughly cook all raw meats. - Wash raw vegetables before eating. - Keep uncooked meats separate from vegetables and from cooked foods and ready-to-eat foods. - Wash hands, knives, and cutting boards after handling uncooked meats and dairy products. - Avoid raw (unpasteurized) milk or foods made from raw milk. - Always thaw ready-to-eat frozen food in the refrigerator or microwave, not on counter. - Thoroughly reheat food until steaming hot.
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Can Listeriosis be treated?
When Listeriosis 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. Unfortunately, even with prompt treatment, some infections result in death. This is particularly likely in the elderly and in persons with other serious medical problems. Therefore, prevention of infection is key.
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Where can I get further information?
Massachusetts Department of Public Health Division of Epidemiology & Immunization 617.983.6800 Your local health department Your doctor, nurse or health center
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