Listeria Infection (Listeriosis) FAQs

Listeriosis is a disease caused by Listeria monocytogenes , a bacterium commonly found in the soil and water.

Despite being so widespread, most infections in humans result from eating contaminated foods. Vegetables can become contaminated from the soil or from manure used as fertilizer. Animals can carry the bacterium and can contaminate meat and dairy products.

Outbreaks of listeriosis have been linked to a variety of foods, including ready-to-eat foods (such as hot dogs, luncheon meats, cold cuts, fermented or dry sausage, and other deli-style meat and poultry), a variety of raw foods (such as uncooked meats and vegetables), and unpasteurized (raw) milk or foods made from unpasteurized milk.

An infected pregnant woman can pass the infection to her baby while in the womb or during delivery.

Healthy adults and children rarely become seriously ill from Listeria infection. Symptoms may range from showing no symptoms to exhibiting diarrhea, fever, muscle pain, joint pain, headache, stiff neck, backache, chills, sensitivity to bright light, sore throat with fever, and swollen glands.

In older children and adults, complications usually involve the central nervous system and blood stream, but may include pneumonia and endocarditis (inflammation of the lining of the heart and valves). Skin contact with Listeria can cause local abscesses or skin lesions.

The disease affects mainly pregnant women, newborns, older adults, and adults with weakened immune systems. Pregnant women are about 20 times more likely than other healthy adults to get listeriosis.

Although rare, it can be found worldwide. It is estimated that 2,500 people become seriously ill with listeriosis each year in the U.S. In Texas, a few dozen cases of listeriosis are reported each year. A recent cluster linked unpasteurized, soft, white cheese from Mexico illegally sold in the state with a listeriosis outbreak among six pregnant women and seven babies in south Texas and in Houston. Two of the babies died.

By carefully following food safety precautions (see below), persons at risk for listeriosis can substantially reduce their chances of becoming ill. Thorough cooking will destroy Listeria on foods.

People at high risk should refrain from eating deli items, unless they are reheated until steaming hot; soft cheeses (such as feta, Brie, Camembert, blue-veined cheeses, and "queso blanco" or "queso fresco"); refrigerated pâtés or meat spreads; and, smoked seafood (often labeled as "nova-style," "lox," "kippered," "smoked," or "jerky"), unless it is in a cooked dish. Perishable or ready-to-eat foods should be used as soon as possible.

Basic food handling steps will help reduce the risk of being infected with Listeria and other harmful organisms:

• Wash hands, knives, and cutting boards after preparing uncooked foods.
• Wash all raw vegetables or fruit thoroughly before eating.
• Keep raw and cooked foods separate when shopping, preparing, cooking and storing foods. Otherwise, bacteria in juices from raw meat, poultry or fish might contaminate a cooked food.
• Thoroughly cook all food of animal origin, including eggs. Cook raw meat to an internal temperature of 160 degrees Fahrenheit, raw poultry to 180 degrees Fahrenheit, and raw fish to 160 degrees Fahrenheit or until it is white and flaky.
• Keep hot foods hot (above 140 ° F). Keep cold foods cold (at or below 40 ° F). Do not keep them out for longer than two hours at room temperature before eating.
• Use a refrigerator thermometer to make sure that the refrigerator always stays at 40ºF or below.
• Reheat leftovers thoroughly.

Be aware of product recalls issued by the government or health department.

Consult your physician or clinic.

A blood or spinal fluid test (to cultivate the bacteria) will show if you have listeriosis.

Listeriosis is treatable with antibiotics.

The risk for the traveler is generally low, but increases when consuming unpasteurized milk and milk products and prepared meat products. Use care if purchasing milk or milk products; unpasteurized products are probably not labeled, or not labeled as being pasteurized, and usually sold wrapped in cellophane or plastic wrap. At home, avoid consummating unpasteurized milk and milk products and prepared meat products that have been brought from other countries.

About one-third of all listeriosis cases happen during pregnancy. Hormonal changes in the pregnant woman cause changes in the immune system that lead to an increased vulnerability to listeriosis. There is a risk of miscarriage, stillbirth, uterine infection, premature labor, and death of the newborn for women infected with Listeria during pregnancy.

Because the symptoms of listeriosis can take days or weeks to appear and the physical signs are not always obvious, it's very important to follow food safety precautions consistently during pregnancy.

A blood test can be performed to determine if the onset of symptoms is caused by Listeria infection. If you have eaten a contaminated (or recalled) product and do not have any symptoms, most experts believe you don't need any tests or treatment. However, you should inform your physician or healthcare provider if you are pregnant and have eaten the contaminated product, especially if you experience flu-like symptoms within 2 months after eating suspect food.

Early diagnosis and treatment with high doses of antibiotics can prevent infection of the unborn baby and result in the birth of a healthy infant.