Listeriosis is a serious infection caused by the bacterium Listeria monocytogenes. Listeriosis can cause severe illness in newborns, pregnant women, the elderly, and anyone with a weakened immune system. Illness can range from fever and diarrhea to infections resulting in brain damage or death. Healthy adults and children can get infected with Listeria, but they rarely become seriously ill. Listeria is commonly found in the environment in soil and water and on plant material. Listeria has also been found in raw foods, such as uncooked meats and vegetables, as well as in foods that become contaminated after processing, such as soft cheeses and cold cuts at the deli counter. In addition, unpasteurized (raw) milk and foods made from unpasteurized milk may contain Listeria.
In the United States, an estimated 2,500 persons become seriously ill with listeriosis each year; of these, about 92 percent are hospitalized and 20 percent die. Persons at increased risk of serious infection are: pregnant women, newborns, the elderly, and persons with weakened immune systems, including persons with cancer, diabetes, kidney disease, or AIDS, and those who take prescription steroid medications. Pregnant women are about 20 times more likely than other healthy adults to get listeriosis. Although infected pregnant women may only experience a mild, flu-like illness, infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or infection of the newborn.