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Listeriosis: Causes, Symptoms, Treatment and Prevention

  • Synopsis: Published: 2009-04-27 (Revised/Updated 2017-01-25) - Information on Listeriosis a disease that mainly affects seniors newborns pregnant women and adults with weakened immune systems. For further information pertaining to this article contact: Thomas C. Weiss at Disabled World.

Main Document

Quote: "Medical science believes that ingestion of less than one-thousand Listeria bacteria may cause illness in a person who has consumed them."

Listeriosis has recently become recognized as an important public health issue in America. Listeriosis is a form of serious infection that is caused by consumption of foods that have become contaminated with a type of bacteria known as, 'Listeria Monocytogenes.'

Listeriosis is a disease that primarily affects seniors, newborns, pregnant women, and adults who have weakened immune systems. On occasion, people who do not fall into these groups may also be affected by Listeriosis. There are some recommendations to follow that may reduce the risk of contacting this disease.

Symptoms of Listeriosis

Medical science believes that ingestion of less than one-thousand Listeria bacteria may cause illness in a person who has consumed them. There is an incubation period for Listeriosis that ranges between three and seventy days, although it averages about twenty-one days. Listeria is capable of accessing every area of the human body, to include a person's central nervous system, eyes, and heart. Should the infection involve a person's brain, the symptoms they experience can mimic a stroke.

People who have contacted Listeriosis can experience a variety of symptoms. Muscle aches, fever, nausea, and diarrhea are common symptoms of the disease. There is potential for Listeriosis to spread to the person's nervous system; if it does the person may experience symptoms such as a headache, confusion, a stiff neck, loss of balance, or even convulsions. Women who are pregnant and have contacted Listeriosis might experience mild and flu-like symptoms, but resulting infections during a pregnancy may result in miscarriage or stillbirth; premature delivery or an infection in the newborn child.

For reasons that are unknown, in persons who are immune-deficient Listeria both invades and grows best in the central nervous system. Because of this, Listeria causes encephalitis and/or meningitis in these persons. In Pregnant women who have been infected with Listeriosis, the fetus experiences the infection most heavily, leading to spontaneous abortion, sepsis in infancy, or stillbirth. The most at-risk population for contacting Listeriosis is pregnant women; they are approximately twenty-times more likely than other healthy persons to become ill with the disease. Nearly one-third of all cases of Listeriosis happen during pregnancy, and the fetus or newborn is more likely than the mother to experience severe symptoms of the disease. The perinatal and neonatal mortality rate associated with Listeriosis is approximately eighty-percent.

Newborns with a Listeriosis infection may experience symptoms that include:

  • Lethargy
  • Loss of Appetite
  • Vomiting
  • Breathing Difficulty
  • Skin Rash
  • Yellowing of the Skin and Whites of the Eyes

Risks Factors for Listeriosis

It is estimated that two-thousand five-hundred persons in America become seriously ill with Listeriosis every year. Of this group, five-hundred die from the disease. People at greatest risk from Listeriosis include:

  • Newborns: Newborns, rather than the pregnant women themselves, often experience the serious effects of infection in pregnancy.
  • Persons with weakened immune systems
  • Persons with cancer, diabetes, or kidney disease
  • Persons with AIDS: People with AIDS are nearly 300 times more likely to get Listeriosis than people with average immune systems.
  • Persons who take Glucocorticosteroid medications
  • Seniors

Adults who are healthy, as well as children, become infected with Listeriosis on occasion, but rarely become seriously ill.

Listeriosis is treatable, for the most part. The presence of an increasingly immunocompromised population presents a greater threat from Listeriosis. Because Listeriosis is a disease that is easily transmitted from mother to fetus through the placenta, it is a worrisome one for expectant mothers, particularly since pregnant women themselves often do not show outward signs of the disease. Listeriosis is an important threat to public health and deserves notice.

A number of doctors overlook the possibility of Listeriosis as a diagnosis simply because they are not aware of how easily the disease is able to both survive and grow in refrigerated foods. Large outbreaks have been caused by lunch meats and hot dogs that have been contaminated; these are foods that have previously not been considered to be dangerous. There is a need for ongoing research so that the intricacies and mechanisms of this disease can be better understood. More than anything, notions concerning the proper storage of foods need to be updated so that contamination can be kept to a minimum.

Food Contamination and Listeriosis

The bacteria that cause Listeriosis can be found in both soil and water. Vegetables may become contaminated through soil, or from manure that has been used to fertilize vegetables. Animals may carry the bacteria and yet not appear to be sick, then go on to contaminate food products that are of animal origin such as dairy and meat products. Listeriosis bacteria have been discovered in a number of raw foods, including raw vegetables and uncooked meats. Even processed foods have become contaminated after they have been processed; cold cuts and cheeses for example. The bacteria may be present in unpasteurized milk or foods that have been made from unpasteurized milk. Listeria is killed through the process of pasteurization and cooking, although there are some specific, ready-to-eat foods such as deli meats and hot dogs that may become contaminated after they have been cooked but have yet to be packaged.

Contacting Listeriosis

People can get Listeriosis through consumption of foods that contain the bacteria for the disease. Babies may be born with Listeriosis if their mothers have eaten contaminated foods while they were pregnant. Persons who are considered to be healthy can eat contaminated foods and may not become sick, although people who are at an increased risk for the infection may get Listeriosis after eating something that has been contaminated with even a few bacteria. You can avoid Listeriosis by avoiding certain high-risk food products and by handling foods appropriately.

Preventing Listeriosis

There are some general guidelines for the prevention of Listeriosis, and they are similar to the ones that are used in order to prevent other types of food-born illnesses like Salmonella. These guidelines include:

  • Consume perishable and ready-to-eat foods as soon as possible
  • Wash raw vegetables thoroughly before eating.
  • Thoroughly cook raw food from animal sources, such as beef, pork, or poultry.
  • Avoid unpasteurized (raw) milk or foods made from unpasteurized milk.
  • Keep uncooked meats separate from vegetables and from cooked foods and ready-to-eat foods.
  • Wash hands, knives, and cutting boards after handling uncooked foods.

There are some recommendations for people who are at higher risk for Listeriosis, to include women who are pregnant and people with weakened immune systems, that go along with the recommendations above. These recommendations include:

  • Do not eat hot dogs, luncheon meats, or deli meats unless they are reheated until they are 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 pates or meat spreads. Canned or shelf-stable pates and meat spreads may be eaten.
  • Do not eat refrigerated smoked seafood, unless it is contained in 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 shelf-stable smoked seafood may be eaten.

Recognizing Listeriosis

At this time there is no routine screening test for Listeriosis. Should you experience symptoms such as a stiff neck or fever you should consult a doctor. They may order either a blood test or a spinal fluid test that will show if you have the infection. For women who are pregnant, a blood test is the most reliable test to show whether or not the symptoms you are experiencing are due to Listeriosis. If you have eaten a food product that has been recalled because of Listeria contamination, be aware that the risk of a person developing Listeriosis after eating a contaminated product is small. If you are a member of a high risk group and have eaten one of these products, and are experiencing symptoms within two months such as fever or other signs of serious illness, you should contact your doctor and inform them about the exposure.

Pregnant women who receive antibiotics promptly may prevent infection of the fetus or newborn. Babies with Listeriosis receive the same antibiotics as adults with the infection, although antibiotics are often used in combinations until a doctor is certain of the diagnosis. Despite prompt treatment, the Listeria infection still sometimes results in death; something that is more likely in seniors and persons with additional serious medical issues.

Related Information:

  1. Listeria Bacteria Make Food Poisoning Unpredictable - Society for General Microbiology - (Sep 06, 2010)
    https://www.disabled-world.com/fitness/nutrition/foodsecurity/listeria-bacteria.php
  2. Focus on Food Safety as Part of a Healthy Eating Plan - American Dietetic Association - (Mar 09, 2011)
    https://www.disabled-world.com/fitness/nutrition/foodsecurity/food-preparation.php
  3. Bio-K+ CL1285 Probiotic Fights Listeria Monocytogenes Bacteria - Information and effectiveness of Probiotic Bio-K+ CL1285® in inhibiting the growth of pathogenic bacteria including Listeria monocytogenes - Bio-K + International inc.


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