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Listeriosis - Disease Investigations Branch

Listeriosis

What is listeriosis?

Listeriosis an illness that can result from eating foods contaminated by the bacteria, Listeria monocytogenes. Pregnant women, newborns, the elderly and persons with weakened immune symptoms are most commonly affected and are more likely to have severe illness.

How do you get it?

L. monocytogenes is found in soil and water. Vegetables can become contaminated from the soil or from manure used as fertilizer. Animals can also carry the bacteria without seeming ill, and can cause contamination of foods such as meats and dairy products.

You can get listeriosis by drinking or eating raw (unpasteurized) milk or milk products, or from consuming contaminated raw vegetables. The bacteria are sometimes found in ready-to-eat meat products. You can also get it through direct exposure to the feces and fetuses from infected animals. Person-to person transmission can occur through sexual contact. A pregnant woman infected with the bacteria can transmit the disease to her unborn child. This can result in the death of the fetus, premature birth of the child, or infection of the child after it is born.

What are the symptoms of listeriosis?

The symptoms include sudden onset of fever, intense headache, nausea, and vomiting. If the disease progresses to infection of the brain and spinal cord (meningoencephalitis), it can produce delirium, shock, and coma.

Infected pregnant women may have only a mild, flu-like illness, but infections during pregnancy can cause miscarriage, stillbirth, premature delivery, or illness in the newborn.

When do the symptoms start?

The symptoms may start in as few as 3 days or as many as 70 days after eating or drinking a product contaminated with the bacteria.

What is the treatment for listeriosis?

A doctor can prescribe medicines to treat listeriosis. When a pregnant woman becomes infected, medicine needs to be given right away to prevent infection in the fetus or newborn.

How can you keep from getting it?

Do not drink or eat unpasteurized (raw) dairy products.

Avoid eating raw or undercooked meats.

Wash fruits and vegetables well before eating.

Always treat raw poultry, beef, and pork as if they were contaminated. Keep food that will be eaten raw, such as vegetables, from becoming contaminated by animal products. Do not lick your fingers, touch other foods, or smoke a cigarette before washing your hands after handling raw meat.

Wash cutting boards thoroughly after contact with each food, so that the boards do not contaminate the next food prepared.

Pregnant women, the elderly and those with weak immune systems should avoid exposure to anyone or anything possibly infected with listeria. This includes avoiding contact with persons known to have listeriosis and avoiding exposure to any diseased farm animals or aborted animal fetuses.

Download pdf version of this fact sheet

For more information, see the CDC’s website.

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