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Listeria Infections

What Are Listeria Infections?

Listeria infections — known as listeriosis — are a rare type of food poisoning. They can happen when someone eats a food contaminated by a type of bacterium.

Most cases affect pregnant women in their last trimester, newborns, older adults, and people whose immune system is weakened by diseases such as cancer or HIV.

What Are the Signs & Symptoms of Listeria Infections?

Listeria (liss-TEER-ee-uh) infections can cause symptoms such as:

Pregnant women with an infection may only have mild flu-like symptoms, like muscle aches, but are at risk for premature delivery and other serious complications to their fetus.

How Do People Get Listeria Infections?

Listeria infections are caused by Listeria monocytogenes bacteria, which can spread through soil and water.

People can ingest the bacteria by eating foods such as deli meats and cold cuts, soft-ripened cheese, undercooked chicken, uncooked hot dogs, shellfish, and unpasteurized (raw) milk or dairy products made from raw milk.

Are Listeria Infections Contagious?

Listeriosis doesn't pass from person to person. People become infected by ingesting contaminated food or fluids. However, a pregnant woman can pass the infection to her unborn baby.

How Is Listeriosis Diagnosed?

Doctors usually diagnose Listeria infections with a lab test called a bacterial culture, done on a sample of a body fluid, such as blood, spinal fluid, or the placenta.

The earlier listeriosis is detected and treated, the better, because it can cause a serious and life-threatening infection.

How Is Listeriosis Treated?

Healthy kids, teens, and adults with a Listeria infection typically don't need treatment. Symptoms usually go away within a few weeks.

Pregnant women and newborns with listeriosis will receive antibiotics in the hospital through an intravenous catheter (IV) into a vein. Treatment lasts for about 10 days, but that can vary depending on the body's ability to fight off the infection.

Children whose immune systems are compromised by illness or infection, such as cancer or HIV, are more likely to develop severe listeriosis infections and may need further treatment.

What Problems Can Happen?

Some people with severe Listeria infections — especially those with weakened immunity and people over age 65 — can develop gastroenteritis (vomiting and diarrhea, also called the "stomach flu"), bacteremia (a bacterial infection in the blood), sepsis (a dangerous full-body response to bacteremia), meningitis, pneumonia, osteomyelitis (infection in a bone), and endocarditis (inflammation and infection of the heart's lining).

Can Listeria Infections Be Prevented?

Particularly if you are pregnant or in one of the other high-risk groups, avoiding certain foods and drinks can reduce your risk of getting this infection.

Other tips to help protect your family from listeriosis (and other foodborne illnesses):

  • Always cook food (especially meat and eggs) well to the proper internal temperature.
  • Wash fruits and vegetables well before eating.
  • Only drink pasteurized milk, and make sure that milk is refrigerated at the appropriate temperature, which is below 40°F (4°C).
  • Avoid foods made from unpasteurized milk.
  • If you're in a high-risk group, avoid soft cheeses such as feta, Brie, Camembert, blue-veined cheeses, and Mexican-style cheeses (like queso fresco).
  • Reheat precooked, prepackaged foods — such as deli meats or hot dogs — to steaming hot temperatures, especially if you're pregnant.
  • Carefully wash hands and utensils after handling raw foods.

When Should I Call the Doctor?

Call your doctor immediately if your child develops fast or labored breathing, a fever, loss of appetite, vomiting, dehydration, a high-pitched cry, excessive sleepiness, or irritability. If your child has listeriosis, the doctor can immediately start treatment.

Reviewed by: Rebecca L. Gill, MD
Date reviewed: November 2017

Note: All information on KidsHealth® is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.

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