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Listeriosis During Pregnancy

This stomach bug is a big fear of moms-to-be because of its potential risks. Find out how to prevent it and protect baby.

What is listeriosis?

Technically speaking, listeriosis is an infection caused by Listeria monocytogenes bacteria. Practically speaking, listeriosis is a type of food poisoning that can—but almost never does—cause pregnancy complications.

Listeria bacteria are found in the soil, in water and in sewage. It can also contaminate food and plants. If a person eats something that’s been contaminated with listeria, she can develop listeriosis. 

Listeriosis can make people feel sick, but rarely causes severe health problems. What’s scary for moms-to-be, however, is that having it during pregnancy is associated with an increased risk of miscarriage, stillbirth and preterm birth. Babies of moms who had listeriosis during pregnancy are also at risk for listeria infection.

What are the symptoms of listeriosis during pregnancy?

“The symptoms of a listeria infection look a lot like a  cold or mild flu,” says Kelly Kasper, MD, ob-gyn and associate clinical professor at the Indiana University School of Medicine. “The most common symptom is a fever. You might also have  muscle aches or a sore throat.” Some people also have diarrhea

Because the symptoms are so nonspecific, it’s impossible to tell if you have listeriosis solely based on symptoms. That’s why doctors tell pregnant women to contact their health care provider if they’re running a fever—not because they’re always worried about listeriosis, but because fever is a symptom of all kinds of ailments, many of which should be diagnosed and treated right away. The only way to figure out if your symptoms pose a threat to you or baby is to have them checked out by a qualified health care provider.

Are there any tests for listeriosis?

Yep. If your doctor suspects listeriosis—if you have symptoms of listeriosis and have recently eaten some suspect food, for instance—he can order a simple blood test to determine if you have listeriosis or not.

How common is listeriosis during pregnancy?

Not common at all!

It’s true that pregnant women have an increased risk of contracting listeriosis, but the real risk is still tiny. Put it this way: Each year, there are approximately 1,600 cases of listeriosis in the United States. Only about 1 in 7 cases—or about 200 cases per year—occur in pregnant women, out of nearly 4 million pregnancies annually.

“You’re much more likely to step outside and slip on ice on your front steps in the winter than you are to contract listeria,” Kasper says. And good news: Even if you get listeria, baby might not; transmission of listeriosis from mom to baby is not a sure thing. Plus, listeria infections are easily treatable with antibiotics.

How can I get listeriosis?

Most people get listeriosis from contaminated food. In 2014, eight people contracted listeriosis after eating cheese products from Roos Foods; the FDA suspended the company’s food facility registration and recalled both hard and soft cheeses, butter and sour cream manufactured at that facility after finding “unsanitary conditions” during an inspection.

In 2011, contaminated cantaloupe caused the nation’s largest outbreak of listeriosis.

The listeria bacteria is killed with heating and pasteurization, so listeriosis is most commonly related to eating uncooked meats or vegetables, raw or unpasteurized milk products, or processed foods (such as hot dogs or lunch meat) that become contaminated after being cooked at the food processing facility.

How will listeriosis affect baby?

It probably won’t. While listeriosis increases the risk of miscarriage, stillbirth,  preterm delivery and listeriosis infection of the newborn, the odds of anything happening bad happening to baby is slim. Here’s why:

    • Listeria infection can spread from mom to baby through the placenta, but it’s not a sure thing. So even if you get listeriosis, baby might not. The antibiotics used to treat listeriosis can prevent infection of the fetus.

    • Antibiotics can also be used to treat (and prevent complications of) newborn listeriosis. While listeriosis of the newborn can cause severe blood infections, meningitis, pneumonia and even death, treatment with antibiotics can resolve the infection and usually prevent complications.

What’s the best way to treat listeriosis during pregnancy?

Oral antibiotics can effectively treat listeriosis during pregnancy. Taking the antibiotics can help baby as well. Research shows that treating moms-to-be with high doses of antibiotics during pregnancy decreases the incidence of listeriosis-related preterm births and stillbirths.

What can I do to prevent listeriosis during pregnancy?

If you want to decrease your risk of listeriosis to almost zero, you can follow the official listeriosis prevention guidelines and not eat any unpasteurized soft cheeses, refrigerated smoked seafood, raw or unpasteurized milk products, or cold (or room temp)  deli meats or hot dogs for the duration of your pregnancy.

Or you can take a slightly more relaxed approach. Given the extreme improbability of contracting listeriosis from properly handled foods, Kasper suggests eating food you’ve prepared yourself and following common sense guidelines when you prep and store it:

    • Store foods safely. Make sure your refrigerator is set to 40 degrees Fahrenheit or below, and return items to the fridge as soon as possible after using. Don’t let foods sit out for long periods at room temperature.

    • Pay attention to expiration dates. If your lunch meat is past its expiration date (or if it smells or looks funny), throw it away. Otherwise, enjoy!
“You want to be smart about listeria and keep yourself healthy. But at the same time, you don’t want to quit living,” Kasper says. “There are some things that we know are very important, common and threatening to a pregnancy, like influenza; that’s why we recommend the flu shot. Listeriosis is very uncommon. You don’t have to put yourself in a plastic bubble because you’re afraid of what might happen.”

What do other moms do about listeriosis?

"I know it's rare but my doula ate a sub and she got so sick from listeriosis she went into labor. Thankfully she was full term. My OB is very strict about [sticking to safe foods]. That says something about the potential dangers. Something to keep in mind—to me [eating certain foods is] not worth the risk."

"A friend of mine had listeriosis during her first pregnancy—the baby was okay!—and from what she told me, it was constant, uncontrollable vomiting. She said she was puking every five minutes, for a good hour or so. Poor thing!"

"A woman who goes to my OB practice did get listeriosis while I was pregnant with my first child and it did not have a good outcome. Even the doctors in the practice were shocked because it is so rare."

Are there any other resources for listeriosis during pregnancy?

USDA: Protect Your Baby and Yourself from Listeriosis

Expert source: Kelly Kasper, MD, ob-gyn and associate clinical professor at the Indiana University School of Medicine.



PHOTO: Getty Images