Listeria infection

Listeria infection: Causes, Symptoms, Diagnosis And Treatment

Listeria is a foodborne bacterial infection that can be fatal if it infects a pregnant woman. In many cases, people remain unaware of its existence. However, in serious cases, the infection spreads to the patient’s nervous system causing symptoms like headache and confusion. In such cases necessary treatment should be provided for listeria infection symptoms otherwise it can be life-threatening.

People aging 65 and above, people with weak immune systems and pregnant women are highly susceptible to develop this bacterial infection. The consumption of unpasteurized milk products and inappropriately processed deli meats are the most common reason behind the growth of this infectious disease.

People with a strong immune system hardly get ill from this infection but it can be proved fatal to unborn babies, infants, and people with weak immune power. In such cases, immediate antibiotic treatment can help in coping with its symptoms and preventing its serious health impacts.

The bacteria that cause this foodborne disease are called Listeria bacteria which can easily survive in the refrigerator even in the freezer. So people with high-risk factors should avoid eating foods that are more likely to contain these bacteria. Otherwise, they will easily get infected leading to serious health outcomes that will appear in no time.

In this health article, you will get to know about every important aspect of this foodborne bacterial illness which is important for the prevention of this infectious disease, especially for high-risk group people.

What Is Listeria Infection?

listeria <a href=infection symptoms” width=”512″ height=”269″ />Listeria Infection is also known as Listeriosis, a foodborne infection caused by Listeria bacteria, named after Joseph Lister a surgeon who has pioneered antiseptic surgery. The Listeria bacteria has ten different species out of them the variant that mostly causes Listeria infection in humans is Listeria monocytogenes.

Previously the Listeria infection has caused approx. 1600 illnesses and 260 deaths cases in the U.S. each year in the pasts however this outbreak condition has now become more stable over recent years. Usually, this infection occurs out of the consumption of contaminated food to any age group people. However, people with weak immune power, pregnant women and older adults are a more common victim of this bacterial infection who develops serious symptoms that even may lead to death. About 20 to 30 percent of total Listeria infection cases are fatal ones.


Listeria bacteria cause listeriosis infection that exists in water, soil, and animal feces. This foodborne bacteria can be found in the following food products-

  • Unpasteurized milk or food products made with this milk
  • Contaminated meat
  • Raw vegetables that are grown in contaminated soil or soil in which contaminated manure is used as a fertilizer
  • Some processed food products such as hot dogs, deli meats, and soft cheese that has been contaminated after its processing
  • Some other food products that can harbor listeria includes cantaloupe, caramel apples, etc.

Apart from these food sources, an unborn baby can contract this bacterial infection from his or her mother. Adults with the strong immune system are the least victim of this foodborne disease. It is more likely to develop in people with a weak immune system whose body can’t fight back this bacterium and outgrow its symptoms.

Listeria Infection Symptoms

The incubation period of Listeria infection is not fixed. It can be anything between 11 to 70 days after the consumption of contaminated food. The initial time symptoms of this bacterial infection may not be clear for some time.  The symptoms that may last for 1 to 3 days after the contraction of this bacterial infection include-

  • Fever
  • Chills
  • Nausea
  • Vomiting
  • Upset stomach
  • Diarrhea
  • Muscle aches
  • Flu-like symptoms

For many people, the symptoms remain unnoticed even after the contraction of this infection however for some people the infection spreads to their nervous system that leads to following symptoms growth-

  • Headache
  • Confusion
  • Loss of balance
  • Tremors
  • Convulsions
  • Stiffness in neck

In the cases of susceptible people, the listeria infection may lead to severe blood infection known as septicemia or meningitis a health condition in which inflammation occurs in the membranes around the brain. The cases where listeria infection spreads to the brain can lead to severe outcomes including-

  • Encephalitis an inflammation of the brain
  • Paralysis and tremors
  • Meningitis, an inflammation of membranes around the brain and spinal cord
  • Meningoencephalitis, a combination of both meningitis and encephalitis health conditions
  • Cerebral abscesses a condition in which pus build-up occurs within the brain

Symptoms during Pregnancy and for Infants

During pregnancy, women are more likely to develop listeria infection with a comparison to other people. The cases of listeriosis in pregnant women stand 12 per 100000 with comparison to 0.7 per 100000 in the overall population. Possibility remains that a listeriosis infected pregnant mother would not develop any outward symptoms but internally the unborn baby is getting severely impacted. In such cases, a premature baby birth may happen or miscarriage may occur.

Also if premature birth occurs then the possibility remains that newborn infants will take birth with a life-threatening infection that continues for a few days to weeks time after birth. The symptoms in a newborn child are usually subtle including-

  • Fever
  • Vomiting
  • Irritability
  • Lack of interest in feeding

When to contact a doctor

If you or anyone notices the sign of listeriosis after the consumption of food immediately or after some time such as nausea, fever, muscle ache, and diarrhea then without further delay you should immediately contact your doctor. Also, foods that are susceptible to cause illness after their intakes such as food products made with unpasteurized milk or improperly processed deli meats then you should see a doctor.

If you notice symptoms like severe headache, high fever, stiffness in the neck, sensitivity to light, and confusion then you should seek emergency medical care. These are the symptoms of bacterial meningitis a life-threatening complication associated with Listeria infection.

Risk Factors

Pregnant women and people with weak immune systems are the most common victim of this foodborne bacterial illness. The weakness of immunity can occur due to other health condition that impacts the human immune system such as AIDS, and cancer.

The risk for pregnant women and their babies

Pregnant women are more susceptible to develop listeria infection with comparison to other adults who are in a healthy position. Though usually, it causes only mild level symptoms in the infected woman, its worst impact can be seen in the unborn baby’s health. If a pregnant women contract listeria it can lead to-

 People with weak immune systems

The following group of people has generally very weak immune system and risk to grow listeria infection-

  • People aging older than 65
  • People diagnosed with AIDS (acquired immune deficiency syndrome)
  • Those who are receiving chemotherapy
  • Diabetic people
  • People diagnosed with kidney disease
  • People affected by cirrhosis
  • Those who are taking high-dose prednisone or certain rheumatoid arthritis medications or immunosuppressant medications
  • People who are taking certain medications to block the rejection of transplanted organ
  • People whose spleen is removed surgically


In more than an average number of listeria infection cases, the symptoms are too subtle that they remain unnoticed. However, in certain cases, it can cause life-threatening complications including-

  • Meningitis, an inflammation of the membranes and fluid around the brain
  • Generalized blood infection

If remain untreated these complications can lead to death in the infected person.

Diagnosis and Treatment

After knowing your physical symptoms the doctor will recommend for a blood test which is the most effective procedure to diagnose listeria infection. In certain cases, urine, as well as spinal fluid, are also tested to determine the listeria infection.

Once your test reports show positive result the doctor will start further treatment procedures to cure this infectious disease. The treatment procedure will depend and vary on the basis of signs and symptoms an infected patient is developing particularly. People who develop mild level symptoms usually do not require any special treatment. The symptoms automatically disappear after some time. However, in cases of more serious symptoms, the patient is treated with antibiotics doses.

In the cases of pregnant women contracting this foodborne bacterial illness immediate antibiotic treatment may help in coping with these infection symptoms and in obstructing its impact on the unborn baby’s health. Ampicillin drugs can be given alone or can be given along with another antibiotic such as gentamicin. The cases where the infected patient develops the symptoms of meningitis or septicemia as a result of listeria infection, intravenous antibiotics are required to give the affected patient. Also, they need care and treatment for at least six weeks.

Home Remedies

The mild form of listeria infection can be easily treated and managed at home itself with some safe and effective home remedies mentioned below-

  • Drink plenty amount of water to keep your body fully hydrated. In case you are experiencing diarrhea or vomiting then rehydration is very necessary which can easily be done with clear liquids and plain water.
  • Avoid the intake of foods that are susceptible to trigger the symptoms of this foodborne infection.
  • Eat the BRAT diet. During the transition process of your intestine when it is returning to its normal state, eating foods that are very easy to process can prove helpful and beneficial.  The BRAT diet includes foods like bananas, toast, rice, and applesauce. You should especially avoid your intake of spicy foods, alcohol, dairy products, and meat.
  • In order to reduce your fever and muscle ache, you should switch between acetaminophen (Tylenol) and nonsteroidal anti-inflammatory drugs (NSAIDs).


This foodborne bacterial infection can be easily prevented by following some healthy cleaning and hygienic habits such as washing hands frequently and appropriately, scrubbing vegetables properly with clean and safe water before cooking them. Similarly, scrub the fruits properly before eating them.

Though listeria is not a very common infection as with comparison to other infectious diseases however, one can prevent their risk of developing this infection in a number of ways. The precaution is very necessary to maintain during pregnancy as this infection proves fatal for the unborn baby if a pregnant women contract this infection.  Some vital precaution measures include-

  • Clean Raw Vegetables Thoroughly- Vegetables grown in contaminated soil or in which contaminated manure has been used contain the listeria bacteria which can easily enter inside the body if these vegetables are not cleaned properly. So to reduce your risk of this bacterial infection you should clean all raw vegetables with warm water. Scrub it thoroughly with a brush. Similarly, fruits should be scrub clean to wash out all suspected harmful microorganisms on its surface and then, and only it should be consumed.
  • Wash Your Hands Frequently- To prevent this bacterial infection illness you should wash your hands frequently like before cooking or serving food. Wash your hands with warm soapy water. With a similar type of water, you should clean your utensils and kitchen slab and surface.
  • Cook Foods Properly- Improperly processed or partially or inappropriate cooking is one of the prominent sources of this foodborne bacterial infection contraction. So to avoid your risk you should cook your foods thoroughly, especially those having the potential to contain this bacteria. Make sure the dish you are using to cook meat and eggs are well heated and remain heated throughout the process. In this context food thermometer usage is effective.
  • Avoid Consuming Certain Meats- The listeria bacteria can easily survive in refrigerated or cold meats. So the consumption of cold meats especially hot dogs, deli meats should be avoided unless cooked at high heat before eating them. Also, you should wash everything thoroughly that comes in the contact of raw or cold cooked meat.
  • Avoid Eating Soft Cheese- Soft cheese is another common bearer of this bacteria. So people with a high risk of this foodborne infection should avoid consuming soft cheeses including Feta, Brie, Camembert, Blue-veined cheeses, Mexican style cheeses such as panela, fresco, queso, and queso Blanco unless these cheese products are labeled with the specification that product is made with pasteurized milk.
  • Avoid Smoked Seafood Intake- Avoid consuming refrigerated smoked seafood until and unless it is thoroughly cooked before eating it.

With the above-mentioned prevention tips, you will not only manage to prevent this infectious illness but will also manage to reduce and cope up with the listeria infection symptoms easily if you develop them. However in the cases of fatal symptoms and if you are a pregnant woman you should seek immediate medical help as negligence in such cases can prove life-threatening.

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