What you need to know about Listeria

Listeria monocytogenes, a common type of bacteria, has recently been recognized as an important public health problem in the United States. Eating food contaminated with the germ causes listeriosis, a serious infection affecting primarily pregnant women, newborns and adults with weak immune systems. It can be avoided by following a few simple recommendations.

What are the symptoms of listeriosis?
A person with listeriosis suffers high fever, muscle aches and sometimes gastrointestinal symptoms such as nausea or diarrhea. If the infection spreads to the nervous system, it can cause symptoms such as headache, stiff neck, confusion, loss of balance or convulsions.

Infected pregnant women often experience only a mild, flu-like illness; however, infections during pregnancy can lead to miscarriage or stillbirth, premature delivery or infection of the newborn.

How common is this type of food poisoning?
In the United States, an estimated 2,500 persons become seriously ill with listeriosis each year. Of these, 500 die. At increased risk are:

• Pregnant women are about 20 times more likely than other healthy adults to get listeriosis. About one-third of listeriosis cases happen during pregnancy.
• Newborns themselves suffer the serious effects from their mother's infection during pregnancy.
• Persons with weakened immune systems and diseases like AIDS, cancer, diabetes or kidney disease.
• People who take steroid medications.
• The elderly.
• Healthy adults and children occasionally get infected with Listeria, but they rarely become seriously ill.

How do you "catch" listeriosis?
You get listeriosis by eating food contaminated with the germ. Babies can be born with listeriosis if their mothers eat contaminated food during pregnancy. Although healthy people can consume contaminated foods without becoming ill, those at increased risk for infection may get listeriosis after eating food tainted with even a few bacteria. Those at risk can prevent Listeria infection by avoiding certain high-risk foods and by handling food properly.

How does Listeria get into food?
Listeria monocytogenes is found in soil and water. Vegetables can become contaminated from the soil or from manure used as fertilizer.

Animals can carry the bacterium without appearing ill and can contaminate foods of animal origin such as meats and dairy products. The germ has been found in a variety of raw foods, such as uncooked meats and vegetables, as well as in processed foods that become contaminated after processing, such as soft cheeses and cold cuts at the deli counter. Unpasteurized milk or foods made from unpasteurized milk may contain the bacterium.

Listeria is killed by pasteurization and cooking; however, in certain ready-to-eat foods such as hot dogs and deli meats, contamination may occur after cooking but before packaging.

The FDA has now approved a mixture of six bacteria-killing viruses that combat strains of Listeria — the blend can be sprayed on ready-to-eat meat and poultry products just before they are packaged.

How to protect yourself
The general guidelines recommended for the prevention of listeriosis are similar to those used to help prevent other food-borne illnesses, such as salmonella:

General recommendations for healthy people:

• 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 and from cooked foods and ready-to-eat foods.
• Avoid unpasteurized milk or foods made from unpasteurized milk.
• Wash hands, knives and cutting boards after handling uncooked foods.
• Consume perishable and ready-to-eat foods as soon as possible.

Additional recommendations for those at high risk, such as pregnant women and people with weak immune systems:

• Do not eat hot dogs, luncheon meats or deli meats, unless they are reheated until steaming hot.
• Avoid getting fluid from hot dog packages on other foods, utensils and food-preparation surfaces, and wash hands after handling hot dogs, luncheon meats and deli meats.
• Do not eat soft cheeses such as feta, Brie, and Camembert, blue-veined cheeses, or Mexican-style cheeses such as queso blanco, queso fresco, and Panela, unless they have labels that clearly state they are made from pasteurized milk.
• Do not eat refrigerated pâtés or meat spreads. Canned or pâtés and meat spreads that are prepared so they don't have to be refrigerated may be eaten.
• Do not eat refrigerated smoked seafood, unless it is part of a cooked dish, such as a casserole. Refrigerated smoked seafood, such as salmon, trout, whitefish, cod, tuna or mackerel, is most often labeled as "nova-style," "lox," "kippered," "smoked," or "jerky." The fish is found in the refrigerator section or sold at deli counters of grocery stores and delicatessens. Canned or smoked seafood that is prepared so it doesn't have to be refrigerated may be eaten.

Can listeriosis be treated?
When infection occurs during pregnancy, antibiotics given promptly to the pregnant woman can often prevent infection of the fetus or newborn. Babies with listeriosis receive the same antibiotics as adults, although 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 particularly likely in the elderly and in persons with other serious medical problems.

What should you do if you've eaten a food recalled because of Listeria contamination?
The risk of an individual person developing Listeria infection after consumption of a contaminated product is very small. If you have eaten a contaminated product and do not have any symptoms, tests or treatments aren't recommended. However, if you are in a high-risk group, have eaten the contaminated product, and within two months become ill with fever or signs of serious illness, you should contact your physician and inform him or her about this exposure.

Source: Centers for Disease Control and Prevention

MORE FROM INFECTIOUS DISEASES

Infectious diseases Section Front

Ebola strain found in pigs for the first time WHO: TB vaccine could kill babies with HIV CDC to reinstate booster shots for HiB vaccine After $196 billion, no proof U.N. programs help Bird flu can linger in landfills Mumps cases rising in parts of Europe New killer virus found in Africa All she lost: My sister's battle with Lyme disease Rare raccoon roundworm blinds teen Immune cell offers clue to malaria deaths Infectious diseases Section Front   Add Infectious diseases headlines to your news reader: