Pregnant women are at high risk for Listeria monocytogenes infections. Almost thirty percent of patients sickened in the current Listeria outbreak linked to caramel apples and plain apples packed by Bidart Brothers are pregnant women. One woman suffered a fetal loss. How are babies infected with this pathogenic bacteria when the mother eats contaminated food?
There are two mechanisms for fetal infection, called early onset and late onset. Early onset occurs when a transplancental infection occurs: the bacteria has progressed to the placenta, where it is shielded from the mother’s immune system and grows rapidly. A Listeria infection in pregnant women usually only produces mild symptoms including fever, headache, chills, back pain, and diarrhea. Those symptoms mimic the flu, which can delay diagnosis.
This type of infection can cause septicemia, pneumonia, and meningitis in the fetus and can result in miscarriage. Another complication from this infection is called granulomatosis infantisepticum that is a serious whole-body infection. The third trimester is the time of highest risk for these infections, since cell-mediated immunity is highest at this point, although miscarriage can occur during any of the three trimesters.
Scientists think that miscarriage is the body’s way of protecting the mother from the bacteria. After miscarriage, the mother usually recovers physically.
The second mechanism for fetal infection is late onset, which affects full term babies who are otherwise healthy. The baby is infected during birth, since the mother sheds the bacteria in the vagina. Symptoms appear in the baby within a few days to a few weeks after birth. Babies infected this way usually develop meningitis, although recovery rates are better than those of early onset listeriosis.
Pregnant women should avoid eating several types of food, including soft cheeses, unpasteurized milk and cheese, deli meats, hot dogs, smoked meats, and undercooked and uncooked meat, shellfish, and eggs. Those foods present the highest risk of contamination by Listeria and other pathogenic bacteria.
Wash produce well before preparation, and avoid cross-contamination between uncooked meats and eggs and foods that are to be eaten raw. Fruits and vegetables can be contaminated with Listeria monocytogenes and other bacteria. The fact that apples were contaminated in this outbreak may be surprising, but there have been recalls of apples for Listeria in the past several years.
Be aware of the symptoms of listeriosis when you are pregnant, and see your doctor immediately if you do become sick with flu-like symptoms. Effective treatment is available if the infection is caught early.
