Listeriosis

Listeriosis is a serious infection caused by eating food infected (contaminated) with a bacteria named Listeria monocytogenes. Newborn babies can also get listeriosis if their mothers ate contaminated food during pregnancy.

Healthy persons may eat listeria-contaminated foods without becoming ill. People at increased risk for infection can become infected after eating food contaminated with only a few bacteria. Persons at increased risk can prevent listeriosis by:

  • Avoiding certain high-risk foods.

  • Handling food properly.

Vegetables can become infected from the soil or from manure used as fertilizer. Animals can carry the bacteria without appearing ill. Animals can infect foods such as meats and dairy products. It has been found in a variety of foods such as:

  • Uncooked meats and vegetables.

  • Foods that become infected after processing.

Foods most likely to be infected after processing include:

  • Soft cheeses.

  • Cold cuts at a deli counter or in a deli section of a grocery store.

Unpasteurized (raw) milk or foods made from unpasteurized milk may also contain Listeria.

The disease affects primarily:

  • Pregnant women.

  • Newborns.

  • Elderly.

  • Adults with weakened immune systems.

Healthy adults and children occasionally get infected with Listeria, but they rarely become seriously ill. Listeria is killed by pasteurization, and heating procedures used to prepare ready-to-eat processed meats should be sufficient to kill the bacterium. However, unless good manufacturing practices are followed, contamination can occur after processing.

RISK FACTORS

  • Pregnant women are at a higher risk than other healthy adults to get listeriosis. Infections are most likely not life-threatening for the pregnant women. However, listeriosis is very dangerous for the unborn or newly born child.

  • Persons with weakened immune systems because of:

  • AIDS.

  • Cancer of various types (particularly lymphoma).

  • Organ transplantation and anti-rejection drugs.

  • Steroid medication for any reason.

  • The elderly.

  • Persons with alcoholism, severe liver disease or diabetes.

SYMPTOMS

A person with listeriosis typically has:

  • Fever.

  • Muscle and joint aches.

  • Problems affecting the stomach and intestines such as:

  • Feeling sick to your stomach (nausea).

  • Vomiting.

  • Diarrhea.

If the infection spreads to the nervous system, symptoms often include headache, stiff neck, confusion and convulsions can occur.

PREVENTION

The general guidelines recommended for the prevention of listeriosis are similar to those used to help prevent other foodborne illnesses:

  • Thoroughly cook raw food from animal sources, such as beef, pork, or poultry.

  • Wash raw vegetables thoroughly before eating.

  • Keep uncooked meats separate from vegetables, cooked foods, and ready-to-eat foods.

  • Avoid unpasteurized (raw) milk or foods made from unpasteurized milk.

  • Wash hands, knives, and cutting boards after handling uncooked foods.

FOR PERSONS AT HIGH RISK:

  • Do not eat hot dogs, luncheon meats, or deli meats, unless they are re-heated until steaming hot.

  • Avoid cross-contaminating other foods, utensils, and food preparation surfaces with fluid from hot dog and deli meat packages. Wash your hands after handling these foods.

  • Do not eat soft cheeses such as feta, Brie, Camembert, blue-veined cheeses, and Mexican-style cheeses such as "queso blanco fresco". Cheeses that may be eaten include hard cheeses and semi-soft cheeses such as:

  • Mozzarella.

  • Pasteurized processed cheese slices and spreads.

  • cream cheese.

  • Cottage cheese.

  • Do not eat refrigerated pâtés or meat spreads. Canned or shelf-stable pâtés and meat spreads may be eaten.

  • Do not eat refrigerated smoked seafood, unless it is contained in a cooked dish, such as a casserole. Avoid refrigerated smoked seafood such as salmon, trout, whitefish, cod, tuna or mackerel. These products are often labeled as:

  • "Nova-style".

  • "Lox".

  • "Kippered".

  • "Smoked".

  • "Jerky".

  • Do not eat the fish found in the refrigerator section or sold at deli counters of grocery stores and delicatessens. Canned or shelf-stable smoked seafood may be eaten.

DIAGNOSIS

  • There is no routine screening test for those who might get listeriosis during pregnancy. If you have symptoms during pregnancy such as fever or stiff neck, call your doctor. A blood or spinal fluid test will show if you have listeriosis. During pregnancy, a blood test is the best way to find out if your symptoms are due to listeriosis.

  • The risk of developing listeria after consumption of an infected product is very small. If you have eaten a infected product and do not have any symptoms, it is not recommend that you have any tests or treatment. This is true even if you are in a high-risk group. However, if you are in a high-risk group, have eaten a possibly contaminated product, and become ill with fever or signs of serious illness, you should contact your caregiver.

TREATMENT

  • When infection occurs during pregnancy, medicine which kill bacteria (antibiotics) given promptly to the pregnant woman can:

  • Alleviate symptoms.

  • Prevent infection of the fetus or newborn.

  • Babies with listeriosis receive the same antibiotics as adults. A combination of antibiotics is often used until physicians are certain of the diagnosis.

  • Even with prompt treatment, some infections result in death. This is more likely in the elderly, newborn babies and in persons with other serious medical problems.

SEEK MEDICAL CARE IF:

  • You think you are infected with the Listeria germ.

  • You develop a fever of 102° F (38.9° C) with nausea, vomiting and/or diarrhea.

  • You develop a fever of 102° F (38.9° C) with muscle aches like the flu.

SEEK IMMEDIATE MEDICAL CARE IF:

  • You develop an unexplained oral temperature above 102° F (38.9° C) or higher.

  • You have a severe headache.

  • You develop a stiff neck.

  • You have convulsions.

  • You become confused.

  • You pass out.