Listeriosis, a serious infection caused by eating food contaminated with the bacterium Listeria monocytogenes, has recently been recognized as an important public health problem in North America. The disease affects primarily pregnant women, newborns, and adults with weakened immune systems. It can be avoided by following a few simple recommendations.

What are the symptoms of listeriosis?

A person with listeriosis has fever, muscle aches, and sometimes gastrintestinal symptoms such as nausea or diarrhea. If infection spreads to the nervous system, symptoms such as headache, stiff neck, confusion, loss of balance, or convulsions can occur.
Infected pregnant women may experience only a mild, flu-likeillness; however, infections during pregnancy can lead to premature delivery, infection of the newborn, or even stillbirth.

How great is the risk for listeriosis?

In the United States, an estimated 2,500 persons becomeseriously ill with listeriosis each year. Of these, 500 die. At increased risk are:
Pregnant women - They are about 20 times more likely than other healthy adults to get listeriosis. About one-third of listeriosis cases happen during pregnancy.
Newborns - Newborns rather than the pregnant women themselves suffer the serious effects of infection in pregnancy.
Persons with weakened immune systems
Persons with cancer, diabetes, or kidney disease
Persons with AIDS - They are almost 300 times more likely to get listeriosis than people with normal immune systems.
Persons who take glucocorticosteroid medications
The elderly
Healthy adults and children occasionally get infected with Listeria, but they rarely become seriously ill.

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 the bacterium without appearing ill and can contaminate foods of animal origin such as meats and dairy products. The bacterium has been found in a variety of raw foods, such as uncooked meats and vegetables, as well as in processed foods that become contaminated after processing, such as soft cheeses and cold cuts at the deli counter.
Unpasteurized (raw) milk or foods made from unpasteurized milk may contain the bacterium.
Listeria is killed by pasteurization, and heating proceduresused to prepare ready-to-eat processed meats should be sufficient to kill the bacterium; however, unless good manufacturing practices are followed, contamination can occur after processing.

Can listeriosis be treated?

When infection occurs during pregnancy, antibiotics give 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 result in death. This is particularly likely in the elderly and in persons with other serious medical problems.