Listeriosis is a kind of food poisoning. Food poisoning is caused by harmful germs in something you eat or drink. It can cause nausea, vomiting, diarrhea, fever and headache.

There are about 1,600 new cases of listeriosis each year in the United States. Most healthy people donít get sick from listeriosis. It mostly affects people with a weak immune system, including newborns, elderly people and people with health conditions, like diabetes or HIV.

Pregnant women are about 20 times more likely than others to get listeriosis. If you get listeriosis during pregnancy, it can cause serious and even life-threatening health problems for your growing baby.

What causes listeriosis?
Listeriosis is caused by bacteria called Listeria. Bacteria are tiny organisms that live in and around your body. Some bacteria are good for your body. Others, like Listeria, can make you sick. Listeria may be found in the soil, water, animals and animal poop.

Most people get listeriosis by eating food that is contaminated with Listeria. Food can come in contact with Listeria in soil, water, animals or animal poop.

Foods that may have Listeria include:

  • Vegetables that come in contact with animal poop in the soil or in fertilizer
  • Meats, including beef, pork and chicken
  • Unpasteurized milk and foods made with it. If a food has been pasteurized, itís been heated to kill bad germs. Milk and juices often are pasteurized. Look for the word ìpasteurizedî on the product label.
  • Hot dogs (and juice from hot dogs) and deli meats, like ham, turkey, salami and bologna
  • Pre-made or cold salads from delis or salad bars
  • Pates or meat spreads that have been kept in a refrigerator. Canned meat spreads are safe.
  • Soft cheeses, like feta, Brie, Camembert, Roquefort, blue-veined, queso blanco, queso fresco or Panela
  • Smoked fish (nova style, lox, kippered or jerky) that has been kept in a refrigerator. Smoked fish is safe if itís canned or you use it in a cooked dish (like a casserole).

Foods can cross contaminate each other. Cross contamination is the transfer of harmful bacteria from one thing to another. For example, if you use the same knife to cut raw chicken and tomatoes and donít wash the knife in between, it can pass Listeria from the chicken to the tomatoes. Or if you get juice from a hot dog package on a knife, it can pass Listeria from the knife to the next food you cut.

You may hear news stories about foods that have been recalled (not allowed to be sold) because of listeriosis. If youíve eaten one of these foods, call your health care provider right away.

How do you know if you have listeriosis?
Signs and symptoms of listeriosis usually start a few days after youíve eaten infected food. But it can take up to 2 months for them to appear. To test for listeriosis, your provider takes a sample of your blood or urine, or fluid from your spine. Your provider sends the sample to a lab for testing.

Listeriosis usually causes mild, flu-like symptoms including:

  • Fever
  • Muscle aches
  • Chills
  • Nausea
  • Diarrhea

If listeriosis infection spreads to your nervous system (brain and spinal cord), symptoms may include:

  • Headache
  • Stiff neck
  • Being confused
  • Trouble with balance
  • Seizures

Call your health care provider if you think you may have listeriosis. Treatment depends on your symptoms. During pregnancy, quick treatment with antibiotics can keep listeriosis from harming your baby. Antibiotics are medicines that kill infections caused by bacteria.

What problems can listeriosis cause during pregnancy?
If youíre pregnant and get listeriosis, you can pass the infection to your baby. This can cause problems like:

  • Miscarriage. This is when a baby dies in the womb before 20 weeks of pregnancy. Having listeriosis early in your pregnancy can increase your chances of having a miscarriage.
  • Stillbirth. This is when a baby dies in the womb before birth, but after 20 weeks of pregnancy. Having listeriosis late in your pregnancy can increase your chances for stillbirth.
  • Premature birth. This is birth that happens too early, before 37 completed weeks of pregnancy.
  • Low birthweight. This is when a baby is born weighing less than 5 pounds, 8 ounces.
  • Life-threatening infections in your baby. If you have listeriosis late in your pregnancy, your baby may be at risk for serious infections, like bacteremia (bacteria in the blood) and meningitis. Meningitis is an infection that causes swelling in the brain and spinal cord. Infected newborns may have health problems, including seizures, blindness and problems with the brain, heart and kidneys.

How can you protect yourself and your baby from listeriosis?
Here are some things you can to help prevent listeriosis:

  • Handle foods safely when you wash, prepare, cook and store them.
  • Wash your hands well with soap and water after contact with animals, animal food, bedding, tanks or animal poop.
  • Wash your hands well with soap and water after using the bathroom.
  • Watch out for cross contamination between yourself, food and any utensils or supplies you use when preparing or eating food.

Last reviewed March 2013

See also: Salmonellosis, Handling food safely, Eating healthy during pregnancy

Most common questions

What is mononucleosis?

Mononucleosis (also called mono) is an infection usually caused by the Epstein-Barr virus (EBV). It’s sometimes caused by another virus called cytomegalovirus (CMV). EBV and CMV are part of the herpes virus family. Mono is most common in teenagers and young adults, but anyone can get it. Mono is called the “kissing disease” because it’s usually passed from one person to another through saliva. In addition to kissing, it can also be passed through sneezing, coughing or sharing pillows, drinks, straws, and toothbrushes.

You can have mono without having any symptoms. But even if you don’t get sick, you can still pass it to others. Symptoms can include:

  • Achy muscles
  • Belly pain
  • Fatigue (feeling tired all the time)
  • Fever
  • Sore throat
  • Swollen glands in your neck

If your symptoms don’t go away or get worse, tell your health care provider. He’ll most likely do a physical exam and test your blood to find out for sure if you have mono.

There’s no vaccine to prevent mono. There’s also no specific treatment. The best care is to take it easy and get as much rest as you can. It may take a few weeks before you fully recover.

Can Rh factor affect my baby?

The Rh factor may be a problem if mom is Rh-negative but dad is Rh-positive. If dad is Rh-negative, there is no risk.

If your baby gets her Rh-positive factor from dad, your body may believe that your baby's red blood cells are foreign elements attacking you. Your body may make antibodies to fight them. This is called sensitization.

If you're Rh-negative, you can get shots of Rh immune globulin (RhIg) to stop your body from attacking your baby. It's best to get these shots at 28 weeks of pregnancy and again within 72 hours of giving birth if a blood test shows that your baby is Rh-positive. You won't need anymore shots after giving birth if your baby is Rh-negative. You should also get a shot after certain pregnancy exams like an amniocentesis, a chorionic villus sampling or an external cephalic version (when your provider tries to turn a breech-position baby head down before labor). You'll also want to get the shot if you have a miscarriage, an ectopic pregnancy or suffer abdominal trauma.

I had a miscarriage. How long should I wait to try again?

Before getting pregnant again, it's important that you are ready both physically and emotionally. If you don't need tests or treatments to discover the cause of the miscarriage, it's usually OK for you to become pregnant after one normal menstrual cycle. However, it may take longer for you to feel emotionally ready to be pregnant again. Everyone responds differently to a miscarriage. Only you will know when you are ready to try to get pregnant again.

Are gallstones common during pregnancy?

Not common, but they do happen. Elevated hormones during pregnancy can cause the gallbladder to function more slowly, less efficiently. The gallbladder stores and releases bile, a substance produced in the liver. Bile helps digest fat. When bile sits in the gallbladder for too long, hard, solid nuggets called gallstones can form. The stones can block the flow of bile, causing indigestion and sometimes serious pain. Staying at a healthy weight during pregnancy can help lower your risk of gallstones. Exercise and eating foods that are low in fat and high in fiber, like veggies, fruits and whole grains, can help, too. Symptoms of gallstones include nausea, vomiting and intense, continuous abdominal pain. Treatment during pregnancy may include surgery to remove the gallbladder. Gallstones in the third trimester can be managed with a strict meal plan and pain medication, followed by surgery several weeks after delivery.

©2013 March of Dimes Foundation. The March of Dimes is a non-profit organization recognized as tax-exempt under Internal Revenue Code section 501(c)(3).