Listeriosis is a dangerous infection caused by eating food that's contaminated with a bacteria called Listeria monocytogenes (L. monocytogenes).

According to the U.S. Centers for Disease Control and Prevention, listeriosis is an important public health problem in the United States.

The bacteria (L. monocytogenes) that causes this disease is common in wild animals, domesticated animals, and in soil and water. The bacteria makes many animals sick and commonly leads to miscarriage and stillbirth in domestic animals.

Vegetables, meats, and other foods you eat can get infected with the bacteria if they come in contact with contaminated soil or manure. Raw milk or products made from raw milk may carry the bacteria.

If you eat the contaminated products, you may get sick. Pregnant women, developing fetuses, newborns, and adults with weakened immune systems are at increased risk. The bacteria most often causes a generalized blood infection (septicemia) or inflammation of the covering of the brain (meningitis).

Infection of a pregnant woman early in pregnancy generally leads to miscarriage. The bacteria may cross the placenta and infect the developing baby. Infections in late pregnancy may lead to stillbirth or death of the infant within a few hours of birth. About half of infants infected at or near term will die.

In infants, symptoms of listeriosis may be seen in the first few days of life and may include:

• Loss of appetite
• Lethargy
• Jaundice
• Vomiting
• Respiratory distress (usually pneumonia)
• Shock
• Skin rash
• Increased pressure inside the skull (due to meningitis) possibly causing suture separation

Late-appearing infection in the infant (symptoms appear age 5 days or older) and infection in children is often seen as meningitis.

In adults, the disease may take many forms depending on what organ or organ systems are infected. It may occur as meningitis, pneumonia, septicemia, and endocarditis, or in milder form as abscesses, skin lesion, and conjunctivitis.

If a pregnant woman becomes infected, it can lead to:

• Stillbirth
• Death of a newborn within a few hours of birth

Laboratory tests may be done to detect the bacteria in amniotic fluid, blood, and urine. A CSF culture may be performed.

Note: There are no special clinical signs to tell the difference between menigitis caused by listeria from other types of meningitis.

Antibiotics are prescribed to kill the bacteria that is causing the infection.

Listeriosis in a fetus or infant results in a poor outcome with a high death rate. Healthy older children and adults have a lower death rate.

Infants who survive listeriosis may have long-term neurological damage and delayed development.

Call your health care provider if signs or symptoms of Listeriosis develop in you or your child.

Pregnant women should avoid contact with wild and domestic animals. Listeria is well controlled in American food products, but food-associated outbreaks have occurred.

Pregnant women should avoid consumption of soft cheeses, deli meats, and cold salads from salad bars. Foreign food products such as nonpasteurized soft cheeses have also been implicated in outbreaks of listeriosis. Food should always be adequately cooked.

Mead P, Slutsker L, Dietz V, et al. Food-Related Illness and Death in the United States. Emerg Infect Dis. 1998; 5(5):607-625.

Tappero J, Schuchat A, Deaver K, Mascola L, Wenger J, for the Listeriosis Study Group. Reduction in the incidence of human listeriosis in the United States: Effectiveness of prevention efforts? JAMA. 1995; 273(14):1118-1122.