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Basics about Listeria

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Listeria is the name of a bacteria found in soil and water. It can be in a variety of raw foods as well as in processed foods and foods made from unpasteurized milk. Listeriais unlike many other germs because it can grow even in the cold temperature of the refrigerator.


Sources Fresh soft cheeses, unpasteurized or inadequately pasteurized milk, ready-to-eat deli meats, hot dogs.
Incubation Period 9-48 hours
Symptoms Fever, muscle aches, and nausea or diarrhea. Pregnant women may have mild flu-like illness, and infection can lead to premature delivery or stillbirth.
Duration of Illness Variable
What Do I Do? If you have symptoms such as fever or stiff neck, consult your doctor. A blood will show if you have listeriosis. When infection occurs during pregnancy, antibiotics given promptly to the pregnant woman can often prevent infection of the fetus or newborn.

Listeria and Pregnancy

Listeria is especially harmful to pregnant women, who are 20 times more likely than other healthy adults to get the infection, as well as their unborn children.

  • During the first trimester, listeriosis may causes miscarriage .
  • As the pregnancy progresses to the third trimester, listeriosis may lead to premature labor, the delivery of a low-birth-weight infant, or infant death . Fetuses who suffer a late infection may develop a wide range of health problems, including mental retardation, paralysis, seizures, blindness, or impairments of the brain, heart, or kidney.
  • In newborns, listeriosis may cause blood infections and meningitis.

To prevent listeriosis and other foodborne infections during pregnancy, consult the Checklist of Foods to Avoid During Pregnancy.

General Information

Listeria Infections (NIH MedlinePlus)
Trusted health information on causes, symptoms, treatment, and prevention.

Listeriosis (CDC)
General information on diagnosis, treatment, prevention, and more.

Listeria monocytogenes (USDA)
General information plus directives and notices, compliance guidelines, and more.

Listeria monocytogenes (FDA)
From the Bad Bug Book; provides basic facts, including associated foods, frequency of disease, complications, and target populations.


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