Listeriosis

What is listeriosis?

Listeriosis is a bacterial infection caused by eating contaminated food. The infection affects mainly pregnant women, newborns, and adults with weakened immune systems.

How does it occur?

The type of bacteria that causes the infection is named Listeria monocytogenes. The bacteria are found in the soil and in some dairy products, such as raw, unpasteurized milk and soft cheeses made from raw milk. Vegetables can become contaminated by bacteria in the soil or in manure used as fertilizer. Animals can carry the bacteria without appearing ill, contaminating foods such as meats and dairy products. In many cases, the source of an infection is not known.

Pregnant women are about 20 times more likely than other healthy adults to have listeriosis. Newborns may be born with the infection and may be much sicker than their mothers.

What are the symptoms?

The most common symptoms are:

• fever
• muscle aches.

Nausea and diarrhea are less common symptoms.

If the infection spreads to the nervous system it can cause meningitis. Meningitis is an infection of the covering of the brain and spinal cord that causes inflammation. Symptoms of meningitis are:

• headache
• stiff neck
• confusion
• loss of balance
• convulsions.

Infected pregnant women may have just mild, flulike symptoms. However, infection in a pregnant woman can lead to preterm delivery, infection of the newborn, and death of the baby.

How is it diagnosed?

Your health care provider will review your symptoms and examine you. The fluid from infected areas of your body, such as the blood, spinal fluid, or joints, will be tested for Listeria bacteria. For example, you may have blood tests. If you have skin sores, they will be checked for bacteria. If you have symptoms of meningitis, your spinal fluid will be checked with a test called a lumbar puncture.

How is it treated?

Your health care provider may prescribe an antibiotic. (Mild infections often get better without an antibiotic.) For a serious infection you may need to take antibiotic medicine for several weeks to make sure all the bacteria are gone. It is important to take all of the antibiotic your provider prescribes. If you stop taking the medicine too soon, symptoms of the infection may return.

When infection occurs during pregnancy, antibiotics given promptly to the pregnant woman can often prevent infection of the baby. If a baby does become infected, the baby will usually need intravenous (IV) antibiotics for several days or even a couple of weeks.

How long will effects last?

The length of illness can vary greatly from person to person. Often the illness is brief and does not require any treatment. However, the infection sometimes causes severe illness, such as meningitis or a blood infection (sepsis). This is more likely in infants, older adults, and people with other serious medical problems.

How can I take care of myself?

• Follow your health care provider's instructions.
• Rest and take acetaminophen or ibuprofen, as recommended by your provider, to relieve your symptoms.
• Call your health care provider right away if you develop symptoms such as a stiff neck or severe headache.
• Call your health care provider if:
  • Your temperature is 102°F (39°C) or higher.
  • Your symptoms are not better in 24 to 48 hours or they are getting worse.
• If you are pregnant and you have fever and muscle aches, call your health care provider.

How can I help prevent listeriosis?

• Wash raw vegetables thoroughly before eating them.
• Cook all meat thoroughly.
• Keep raw meats separate from vegetables, cooked foods, and ready-to-eat foods.
• Avoid unpasteurized milk or foods made from raw milk.
• Wash your hands, knives, and cutting boards with soap after handling uncooked foods.

In addition, if you are pregnant or have a weakened immune system, you should:

• Avoid soft cheeses such as feta, Brie, Camembert, blue-veined, and Mexican-style cheese. (Hard cheeses, processed cheeses, cream cheese, cottage cheese, or yogurt are okay.)
• Cook leftover foods or ready-to-eat foods, such as hot dogs, until they are steaming hot before you eat them.
• Avoid foods from deli counters or thoroughly reheat cold cuts before you eat them.