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Listeria infection

Medically reviewed by Drugs.com. Last updated on Feb 1, 2024.

Overview

Listeria infection is a foodborne bacterial illness that can be very serious for pregnant women, people older than 65 and people with weakened immune systems. It's most commonly caused by eating improperly processed deli meats and unpasteurized milk products.

Healthy people rarely become ill from listeria infection, but the disease can be fatal to unborn babies, newborns and people with weakened immune systems. Prompt antibiotic treatment can help curb the effects of listeria infection.

Listeria bacteria can survive refrigeration and even freezing. So people who are at higher risk of serious infections should avoid eating the types of food most likely to contain listeria bacteria.

Symptoms

If you develop a listeria infection, you might have:

Symptoms might begin a few days after you've eaten contaminated food, but it can take 30 days or more before the first signs and symptoms of infection begin.

If the listeria infection spreads to your nervous system, signs and symptoms can include:

Symptoms during pregnancy and in newborns

During pregnancy, a listeria infection is likely to cause only mild signs and symptoms in the mother. The consequences for the baby, however, can be devastating — the baby can die in the womb or have a life-threatening infection within a few days of being born.

Signs and symptoms of a listeria infection in a newborn can be subtle, but can include:

When to see a doctor

If you've eaten a food that's been recalled because of a listeria outbreak, watch for signs or symptoms of illness. If you have a fever, muscle aches, nausea or diarrhea, contact your doctor. The same goes for illness after eating a potentially contaminated product, such as foods made with unpasteurized milk or poorly heated hot dogs or deli meats.

If you have a high fever, severe headache, stiff neck, confusion or sensitivity to light, seek emergency care. These signs and symptoms can indicate bacterial meningitis, a life-threatening complication of a listeria infection.

Causes

Listeria bacteria can be found in soil, water and animal feces. People can get infected by eating the following:

Unborn babies can contract a listeria infection from the mother.

Risk factors

Pregnant women and people who have weak immune systems are at highest risk of contracting a listeria infection.

Pregnant women and their babies

Pregnant women are much more susceptible to listeria infections than are other healthy adults. Although a listeria infection might cause only a mild illness in pregnant women, consequences for their babies can include:

People who have weak immune systems

This category includes people who:

Complications

Most listeria infections are so mild they can go unnoticed. However, in some cases, a listeria infection can lead to life-threatening complications, including:

Prevention

To prevent a listeria infection, follow simple food safety guidelines:

Precautions for people particularly at risk

If you're pregnant or you have a weak immune system, be particularly cautious about listeria. Take additional precautions with these types of foods:

Diagnosis

A blood test is often the most effective way to determine whether you have a listeria infection. In some cases, samples of urine or spinal fluid will be tested as well.

Treatment

Treatment of listeria infection varies, depending on the severity of the signs and symptoms. Most people with mild symptoms require no treatment. More-serious infections can be treated with antibiotics.

During pregnancy, prompt antibiotic treatment might help keep the infection from affecting the baby.

Preparing for your appointment

If you have eaten food that has been recalled because of listeria contamination, see a doctor only if you have signs and symptoms of a listeria infection.

What you can do

Before the appointment, you might want to write a list that answers the following questions:

You might also want to write a food diary, listing all the foods you've eaten for as far back as you can reliably remember. Tell your doctor if foods you've eaten have been recalled.

What to expect from your doctor

To help with diagnosis, your doctor might ask if you've recently eaten:

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