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LISTERIOSIS AND PREGNANCY
by Dr. Octavia Cannon

What is listeriosis?
Listeriosis or Listeria is an infection caused by Listeria monocytogenes bacteria. The most common source of infection is contaminated food (deli meats, unpasteurized milk/dairy products, soft cheeses, and pate). Once infected, Listeria lives in the gastro-intestinal tract. Only the monocytogenes species is a cause for concern in humans.

Who is at risk for Listeria?
Listeria occurs in 0.7 per 100,000 people or (2500/year). One-third of the Listeria cases are in pregnant women. Pregnant woman and those with a weakened immune system are 20 times more likely to become infected.

What precautions should be taken to avoid infection?
Listeria is usually killed by pasteurization or cooking. Wash all raw vegetables and separate uncooked food from cooked food. Washing your hands, cutting boards, and knives is important. In addition, pregnant women should avoid soft cheeses (Brie, Camembert, Mexican-style, bleu-veined) unless they are in a fully cooked dish. Food should be stored within 2 hours of serving (1 hour in hot weather). Pregnant woman should also refrain from eating pate, meat spreads, refrigerated smoked seafood, and salads made in the grocery store (ham, chicken, egg, tuna, seafood).

How do I know whether I’ve been infected?
Blood tests can detect Listeria. Symptoms range from none to diarrhea, fever, muscle/joint pain, headache, stiff neck, backache, chills, sensitivity to bright light, and sore throat with swollen glands. Symptoms usually begin 2-8 weeks after eating the contaminated food.

Will this affect my baby if I am pregnant?
It is likely that although you have been infected your baby has not. There is a risk of miscarriage, stillbirth, uterine infection, preterm labor and neonatal death. The complications may occur 2-14 days following maternal infection. Early diagnosis and high doses of antibiotics (Ampicillin/PCN) may prevent infection of the unborn baby. No increased risk for pregnancy loss or birth defects has been reported in women who did not have symptoms of infection. There is no evidence that Listeria is a cause for repeat miscarriages in women. There is a slightly increased risk for meningitis in babies, occurring 2 weeks after delivery; likely due to Listeria in the mother’s birth canal.

How can I know if the baby has been infected/harmed?
The same blood test can be performed on the baby after birth. An ultrasound can be used to check for an enlarged heart, thickened bowel, and increased stomach wall thickness in-utero. There is no evidence that breast milk can pass the infection from mother to baby.

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