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What is listeriosis?

Listeriosis is a serious infection caused by consuming foods contaminated with the bacterium Listeria monocytogenes. Pregnant women, young infants, older adults, and those with weakened immune symptoms are at greatest risk for severe illness or death.

What are the symptoms of listeriosis?

Symptoms of Listeria infection may include high fever, headache, and neck stiffness. Listeria infection in pregnant women can lead to miscarriage or stillbirth, premature delivery, or infection of the newborn baby. Healthy adults and children can get infected with Listeria, but usually do not become seriously ill and often are not diagnosed or reported

How common is listeriosis?

In the U.S., an estimated 1,600 people get sick with listeriosis each year and 260 die. In California, approximately 100 people become seriously ill with listeriosis each year and 8 - 9 die.
These groups are at an increased risk of serious illness from listeriosis: 

Older adults and people with weakened i​mmune systems:

  • More than half (58 percent) of reported Listeria infections occur among adults 65 and older.
  • Those with cancer, liver or kidney disease, diabetes, alcoholism, and HIV/AIDS, or on immunosuppressive therapy (i.e., steroids, chemotherapy, radiation), are more likely to get listeriosis.

Pregnant women:

  • About one in seven (14 percent) cases of reported Listeria infections occur during pregnancy. 
  • A pregnant woman may not know she has listeriosis or have very mild symptoms, however: 
    • Infection during pregnancy can cause miscarriage or stillbirth, preterm labor, and illness or death of newborn infants.

How is listeriosis diagnosed?

Listeriosis is usually diagnosed through a blood or spinal fluid test.

How is listeriosis treated?

Listeriosis is treated with antibiotics.

What should you do if you have eaten something contaminated with Listeria?

If a person has eaten food contaminated with Listeria and does not have any symptoms, most experts believe that no tests or treatment are needed. However, pregnant women or people in high risk categories who have eaten foods recalled for Listeria contamination should consult with their health care provider if they develop symptoms within one to two months of eating the product.

How can you prevent listeriosis?

Keep the kitchen clean 

  • Wash your hands with warm, soapy water before and after handling or preparing food. 
  • After cooking, use hot, soapy water to wash the utensils, cutting board, and other food preparation surfaces.

Scrub raw vegetables

  • Scrub raw vegetables with a brush under plenty of running water.

Cook food completely

  • Use a food thermometer to make sure meat, poultry, and egg dishes are cooked to a safe temperature.

In addition to the suggestions above, pregnant women, older adults, and those with weakened immune systems should not eat:

  • Soft cheeses such as Feta, Brie, and Camembert, blue-veined cheeses, or Mexican-style cheeses such as queso blanco, queso fresco, and queso panela, unless they have labels that clearly state they are made from pasteurized milk.
  • Hot dogs, luncheon meats, and deli meats (unless they are heated until steaming hot).
  • Pates or meat spreads from the refrigerated section of the store, or from a deli. Canned meat is not a risk for Listeria.
  • Ready-to-eat cold, smoked, or raw seafood, including nova style, lox, kippered or jerky. Canned seafood is not a risk for Listeria.
  • If you are using any of these products in a casserole or other dish that is cooked completely, these products should be safe to consume.

What is the California Department of Public Health doing about listeriosis?

The California Department of Public Health (CDPH) and local health departments (LHDs) monitor listeriosis. Health care providers are required to report suspected cases of listeriosis to the LHD. When cases are reported, CDPH and LHDs will investigate to find the cause of the illness, prevent further infections, and educate the public.
Improving the safety of food and educational outreach to high-risk consumers such as pregnant women, the immunocompromised, and the elderly may provide the best opportunities for reducing listeriosis.

Where can I get more information on listeriosis?

More information is available on the the U.S. Centers for Disease Control and Prevention Liste​ria  (Listeriosis) webpage.

May 2015 ​ ​​
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