Listeriosis

Overview, Causes, & Risk Factors

Listeriosis is a bacterial infection that strikes humans and animals.

What is going on in the body?

The Listeria bacteria are often passed on to humans in certain foods. Babies may become infected with the bacteria if their mothers are infected during pregnancy or during birth.

What are the causes and risks of the infection?

The Listeria bacteria cause listeriosis. It is often spread by contaminated foods, including:

  • raw fruits and vegetables
  • undercooked meats
  • unpasteurized milk and milk products

    • Listeriosis may also be passed from an infected mother to her baby.

    Symptoms & Signs

    What are the signs and symptoms of the infection?

    Listeriosis usually causes no symptoms in otherwise healthy people. But infection with the bacteria can cause:

  • diarrhea
  • fever
  • headache
  • vomiting

    • Some people may have more serious reactions to infection with the bacteria. Children, the elderly, and people with weakened immune systems are at special risk. They may develop meningitis, an inflammation of the membranes surrounding the brain and spinal cord.

    Babies who have been infected with the bacteria usually get pneumonia. Sepsis, a dangerous blood infection, and meningitis are also common among infected infants.

    Diagnosis & Tests

    How is the infection diagnosed?

    Diagnosis of listeriosis begins with a history and physical exam. The Listeria bacteria is found in infected body fluids and wastes. These include blood, cerebrospinal fluid, and feces.

    Prevention & Expectations

    What can be done to prevent the infection?

    Pregnant women who are found to have Listeria may be given antibiotics to keep it from spreading to their babies.

    Pregnant women and people with weakened immune systems should avoid unpasteurized milk or milk products. They should eat meat only if it is well-cooked. Everyone should wash fruits and vegetables well before eating them.

    What are the long-term effects of the infection?

    Listeriosis can cause serious health problems in newborns and people with weakened immune systems.

    What are the risks to others?

    Listeriosis is generally not contagious from person to person. However, a pregnant woman can pass it to her baby.

    Treatment & Monitoring

    What are the treatments for the infection?

    A combination of the antibiotics ampicillin and gentamicin is the first choice for listeriosis treatment.

    What are the side effects of the treatments?

    The antibiotic combination may cause allergic reaction, upset stomach, and ear damage.

    What happens after treatment for the condition?

    If the infection has caused long-term health problems, the person may need ongoing treatment.

    How is the condition monitored?

    Any new or worsening symptoms should be reported to the healthcare provider.

    Attribution

    Author:Danielle Zerr, MD
    Date Written:
    Editor:Crist, Gayle P., MS, BA
    Edit Date:06/01/01
    Reviewer:William M. Boggs, MD
    Date Reviewed:06/01/01