Listeria is a foodborne illness. It is caused by the bacteria Listeria monocytogenes. These germs are found naturally in the environment, such as in soil and water. But they can sometimes be found in contaminated food.
Anyone can be infected with listeria. For most healthy children and adults, it will cause belly (abdominal) cramps and diarrhea for a few days. But certain groups of people are more likely to get very sick from it. These include people who are pregnant, newborns, very young children, and older adults. People with a weak immune system are also at high risk for more serious disease. So are people taking steroid medicines.
How to say it
lihs-TAYR-ee-uh
What causes listeria?
Eating foods contaminated with germs can lead to the illness. Foods that may become contaminated include:
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Raw or unpasteurized milk.
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Soft cheeses.
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Deli or processed meats.
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Hot dogs.
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Raw vegetables and fruits.
If you're pregnant, you may also pass the germ on to your unborn child.
What are the symptoms of listeria?
In otherwise healthy people, symptoms of listeria may start within 24 hours after infection. But some people have had symptoms as late as 70 days after exposure. Symptoms often last a few days. They may last longer if the germ has spread more widely through the body. Typical symptoms include:
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Fever.
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Body aches.
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Headache.
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Diarrhea.
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Upset stomach (nausea).
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Vomiting.
If the bacteria become more widespread after several weeks, symptoms may include fever, headache, confusion, extreme tiredness (fatigue), backache, and muscle and joint pain.
Listeria can infect the brain. This is more likely to happen in people with a weak immune system. This group includes newborns, very young children, the very old, people who are pregnant, and those with cancer. Symptoms of this infection include:
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Headache.
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Stiff neck.
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Confusion.
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Seizures.
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Tremors.
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Loss of balance or coordination.
How is listeria treated?
Most people who have listeria will get better in a few days. Treatment includes:
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Rest. You may feel better faster if you get plenty of rest.
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Fluids. Drinking lots of fluids will help you stay hydrated. Don’t drink alcohol or have drinks with caffeine.
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Antibiotics. These can kill the bacteria in the body. You may need to take the medicines for 2 to 4 weeks, depending on how widespread the infection is. You may need longer treatment if you have a severe case. Keep taking the medicine until it's gone, even if symptoms go away and you feel better.
When should you contact your doctor?
Contact your health care provider right away if:
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You have a fever of
100.4 °F (38 °C) or higher, or as directed by your provider. -
You can't keep down a normal amount of fluids because of vomiting.
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You feel very weak or dizzy.
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You have sleepiness, confusion, headache, or a stiff neck.
Author: Semko, Laura
© 2000-2026 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
