Listeria Infection

Listeria Infection: Causes, Picture, Symptoms and Treatment

Listeria infection refers to the foodborne illness caused by bacteria. While most people recover from bacterial infection without any serious complications, it can prove serious for pregnant women and people with compromised/weak immunity. The condition, also known as listeriosis occurs when you eat contaminated food. So, it is common among people who use unpasteurized milk products (like cheese) or eat improperly processed meat. While bacterial infection causes no lasting problem to healthy people, it can cause serious issues to unborn babies, newborns, and people with a weak immune system. Therefore, people facing a high risk of the disease must consult their doctor as early as possible. With early medical intervention, it is easy to curb the effects of listeriosis.

About Listeria Infection

listeria infection

While you may think the bacteria Listeria monocytogenes is recent, it is not true. It was discovered by E.G. Murray and J. Pirie, who worked independently on the outbreaks to determine the actual cause of the illness in laboratory rabbits as well as guinea pigs. The first documented case involved a World War I soldier who suffered from meningitis. The consumption of raw food or unprocessed food items can result in bacterial infection. Therefore, you can contract listeria infection when you eat foods like vegetables, meats, dairy, or delicatessen products without heating or cooking it. Since the bacteria causing the problem can survive freezing or refrigeration, you are not safe when you eat the cold food items. Since the infection is an atypical foodborne illness it has triggered a major public health concern.

Symptoms Of Listeria Infection

While the signs associated with the condition can trigger a variety of symptoms depending on the person. It also depends on the specific parts of the boy affected. The initial symptoms may mimic illness caused due to other foodborne germs. But, as the symptoms escalate, it can trigger severe symptoms and result in high fatality rates (20% to 30%).

Initial Symptoms

Otherwise healthy people can develop listeriosis and see the following signs:

  • Nausea
  • Fever
  • Muscle aches
  • Chills
  • Diarrhea

The initial symptoms begin after a few days of contracting the bacteria by eating contaminated food. In some people, the signs can appear from a few days to a month after becoming exposed to the bacteria.

Severe Signs Of Listeria Infection

In high-risk people, the infection can spread to the nervous system. In such cases, you suffer the following signs and symptoms like:

  • Stiff neck
  • Headache
  • Change in alertness
  • Confusion
  • Convulsions
  • Loss of balance

When you see such signs, then it is essential to consult a doctor immediately.

Symptoms In Pregnancy And Newborn Babies

When a pregnant woman suffers from listeriosis, it can trigger only mild symptoms in the mother. But, severe complications occur for the baby. Without treatment, the baby in the womb can suffer from devastating consequences. The life-threatening infection can develop in the womb or within a few days of birth. The subtle yet serious signs in the newborn due to the infection include:

  • Irritability
  • Little interest in feeding
  • Vomiting
  • Fever
  • Difficulty breathing
  • Sensitivity to light

In severe cases, the fetus dies in the womb or the mother can experience a miscarriage. Therefore, pregnant women suspecting the infection need immediate medical attention.

When To Consult A Doctor?

If you suspect the food you have consumed is contaminated or it is recalled due to listeriosis outbreak, then watch your body for signs. With close monitoring, you can detect the signs like fever, nausea, muscle aches or diarrhea early. See a doctor as early as possible to get supportive treatment to avoid escalation of the disease. When you observe the severe signs associated with the disease, then go to the emergency room. The severe signs indicate the affected person has bacterial meningitis, which is a life-threatening complication. Therefore, get the necessary medical help to overcome the problem without lasting complications.

Causes Of Listeria Infection

Listeria bacteria caused by the bacterium Listeria monocytogenes. The bacterium causing the disease is found in water, soil, animal feces. So, people get the infection when they consume the following:

  • Contaminated meat
  • Raw vegetables contaminated from the bad manure (used as fertilizer) or grown in contaminated soil
  • Certain processed foods like deli meats, hot dogs, and soft cheese
  • Unpasteurized milk or milk products made with unpasteurized milk
  • Unborn babies receiving the infection from their mother

Risk Factors Associated With Listeria Infection

Listeria Infection

Not all people suffer the severe consequences of listeriosis. Here are the factors that make you more vulnerable to complications:

Pregnant Women

Pregnant women and their babies are more prone to complications compared to healthy adults. The infection may not cause issues to the health of pregnant women as they suffer only mild issues. But, the consequences for their unborn babies include:

  • Miscarriage
  • Premature birth
  • Stillbirth
  • Suffer from potential fatal infection after birth

People With A Weak Immune System

People who have a weak immune system due to their age or existing medical issues can face increased risk due to listeriosis. Thosewho come under the category include:

  • People who are older than 65 years
  • Individuals suffering from HIV/ AIDS
  • Patients receiving chemotherapy
  • Suffer from diabetes
  • Individual with kidney disease
  • Take certain rheumatoid arthritis drugs
  • Take high-dose prednisone
  • Use medications to avoid rejection of a transplanted organ

Transmission And Contagious Nature Of Listeria Infection

Contagious Nature Of Listeria Infection

You might wonder about the contagious nature of listeriosis. Fortunately, the human-to-human transmission does not occur with the infection. So, in most instances, the infection is not contagious. The only exception is that pregnant mothers can transfer the bacterial infection to their unborn or newborn child.

Listeriosis is mainly a food-borne disease; except in the situation in which a pregnant woman can transfer the bacteria to the fetus or newborn, the disease is not contagious from person to person. So, people who consume contaminated food items suffer from listeriosis. The outbreak is linked to the following food items:

  • Vegetables
  • Fruits
  • Soft Cheese
  • Apples
  • Yogurt
  • Deli meats
  • Smoked seafood
  • Hot dogs

List Of Listeria Infection Outbreak

Is Listeria infection common? The outbreak reports from around the world indicate the infection is common. Here are some of the notable incidents from around the globe:

2017-2018 South African Listeria Outbreak

In one of the world’s worst outbreak, listeriosis in contaminated Deli meats supplied by the South African company, Enterprise Foods caused issues in people who consumed it. The infection from processed meat affected more than a thousand people and resulted in 218 deaths.

European Listeriosis Outbreak

The outbreak started in 2015 that has now affected more than five European countries and resulted in the death of six people. Frozen corn is the cause of infection.

2008 Canadian Listeria Infection

Known as one of the widespread and deadliest outbreaks in Canada, the Listeria infection affected 57 people. The cold cuts manufactured from Maple Leaf Foods caused the death of 22 people.

2011 Cantaloupes Listeria Outbreak

The outbreak had a widespread effect in the USA as it affected more than 147 people, resulting in 33 deaths. From July of 2011 to August 2011, the food poisoning caused widespread panic. It affected people who consumed contaminated cantaloupes distributed by Jensen Farms in Colorado.

Complications Due To Listeria Infection

In most cases, listeria infection is very mild. So, most people never notice the symptoms. It goes away without anyone detecting it. But, in some cases, listeriosis can lead to severe complications. So, people who face a high risk of complications need to see a doctor to get immediate medical treatment.

Complications Suffered By People With Weak Immune System

Without proper treatment, you can face the following:

Generalized Blood Infection

To overcome the infection, your immune system releases a large number of chemicals into your bloodstream. It can result in widespread inflammation. Generalized blood infection can reduce the blood flow to your internal organs and limbs. So, it deprives oxygen and nutrients, leading to multiple organ failure. It can result in death.


Another serious complication associate with listeriosis is the inflammation of membranes as well as fluid surrounding the brain and spinal cord. The condition is medically referred to as meningitis. It can lead to fatal complications.

Complications In Pregnant Women

When pregnant women get the infection, they are at risk of the following problems:

  • Miscarriage
  • Premature delivery
  • Stillbirth
  • Low birth weight of the infant
  • Death of fetus

Pregnant women who suffer from the infection can experience problems to their health that includes:

  • Bacterial meningitis (The inflammation of tissues and membranes surrounding the brain)
  • Blood infection (Septicemia)

Listeriosis can trigger complications in the newborns. So, the infant can suffer from the following issues that need immediate medical attention:

  • Septicemia
  • Pneumonia
  • Bacterial meningitis
  • Death of the baby

Diagnosing Listeria Infection

Since the signs associated with listeriosis mimic several other diseases, you need to see a doctor obtain a proper diagnosis. People who come under high-risk cases need to consult a healthcare professional as early as possible. The doctor performs the following to make a proper diagnosis:

Rule Out Other Diseases

The first step in diagnosing the problem is to sort out the disease from others having similar signs. While it may take a little bit longer, the doctor suggests tests for ruling out the following for a proper diagnosis:

  • Shigellosis
  • Salmonellosis
  • E.coli
  • Botulism

Physical Examination

The most preliminary process of diagnosing the problem is to check the patient’s medical history and a thorough examination. During the examination, you need to convey your recent food habits. Inform regarding the food you have consumed and from where for detect if you suffer from listeria infection.

Bacterial Culture

A definitive diagnosis of the problem is possible only by bacterial culturing. So, you need to provide a sample of any of the following for culturing Listeria monocytogenes bacteria:

  • Blood
  • Amniotic fluid
  • Cerebrospinal fluid

The culturing opted on a medium selective for the bacteria (like RAPID’L mono agar) can offer a clear diagnosis. Based on the test results, your doctor can determine the presence of the bacteria. But, no reliable tests are available to test the presence of bacteria in the stool. With no serological tests (blood tests determining the specific type of protein linked to bacteria or the antibodies associated with the bacteria), your doctor waits for bacterial culture report for diagnosing the problem.

Treatment For Listeria Infection

Listeriosis can clear itself spontaneously in the majority of the people within a week. So, people can see an improvement in their symptoms after the specified time. But, people coming under the high-risk cases, especially women who are pregnant need to consult their doctor immediately when they see signs of the disease. They need immediate treatment to prevent, stop or slow down the development of the disease into a severe complication. Once you see a doctor for the disease, the treatment suggested depends on the severity of your symptoms as well as your overall health.

 Treatment For Mild Listeria Infection

People who are otherwise healthy and only suffer from mild symptoms may not require any specific treatment to clear the problem. But, it is essential to see a doctor for proper guidance to overcome the problem. In most of the cases, for dealing with mild symptoms, your doctor instructs you to stay at home. You can care for your health at home and ensure close follow-up. The home treatment for listeriosis is similar to the treatment options adopted for any foodborne illness. The remedies you can try at home includes:

Avoid Dehydration

The infection can cause vomiting and/or diarrhea. So, you need to compensate for the loss of fluids from your body to avoid dehydration. So, drink water and clear liquids as it keeps the water balance in your body. It also helps maintain your blood pressure.

Take Pain Medications

You can suffer from muscle aches and fever as a result of the infection. So, you can take over-the-counter medications like acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce the discomfort caused by fever and muscle aches.

Follow BRAT Diet


BRAT (Bananas, Rice, Applesauce, Toast) is the bland diet suggested even for small children with an upset stomach. So, you can adopt the diet to give your stomach a chance to heal by resting it. The diet will reduce the amount of stool produce and give enough time for your intestine to heal. Since the diet consists of food that is easy to process by your stomach. It is better to avoid certain food items that can worsen the condition like:

  • Dairy
  • Spicy foods
  • Fatty foods (like meat)
  • Alcohol

Medical Treatments For Severe Listeria Infection

For severe symptoms, you need to go to a doctor immediately. It is important to get medical assistance in the hospital when you feel worse of show advance signs of infection. You need to stay in the hospital to get the necessary treatment. In such cases, all the medications are provided through IV (intravenously). Your doctor suggests the following treatment options for severe cases of listeria infections:

Antibiotics Treatment

For severe cases of infection, staying at a hospital provides round the clock care. So, the hospital staff can check for any complications and intervene at the right time to avoid complications. The treatment includes:

  • To reduce the severity of the infection, the doctor suggests taking antibiotics. It is usually provided through IV lines.
  • For maintaining blood pressure and stay hydrated, the doctor suggests providing fluids through IV. So, It keeps you pressure in check and avoids dehydration.
  • If you experience severe vomiting or nauseous feeling, you need medications to reduce the discomfort and loss of fluids.
  • In case of severe infection, your doctor puts you in mechanical ventilation.

Treatment In Pregnancy

When a pregnant woman suffers from listeriosis, they need immediate treatment to prevent complication to theirs as well as their baby’s health. In most cases, doctors suggest antibiotic treatment to prevent the escalation of signs. The doctor also monitors the baby closely to detect any signs of distress. Babies with infected mothers can contract the infection. In such cases, the newborn babies receive antibiotics to heal the infection as soon as they are born.

It takes only a little time to recover from mild infection. So, you can get back to your normal life within three to five days. So, recovery from a mild case of infection is quick. But, severe cases of infection requires more time to heal. Based on the severity of the infection, you will take time to get back to your normal life. With invasive infection, you require up to six weeks to heal. You have to stay in the hospital for the duration of the treatment and wait till you recover to go back home. An infant born with the infection needs to remain on antibiotics for several weeks until their body becomes capable to fight the infection. So, the newborn needs to remain in the hospital.

Preventing Listeria Infection

To prevent Listeria infection, you need to follow some simple and effective food safety guidelines. So, you need to follow the pointers suggested:

Clean Everything

You need to avoid contamination by cleaning your hands, counters, and appliances. To reduce the possibility of cross-contamination, you have to wash your hands with soap and water before and after cooking, unloading groceries, and cleaning the produce.

Scrub Produce

The produce you bring from the market needs thorough cleaning to avoid contamination. So, place the fruits and vegetables under running water and scrub the produce with a brush. You need to scrub the fruits and vegetables even if you use them after peeling.

Cook Food Well

Avoid using undercooked or raw food as it can result in bacterial infection. Kill the bacteria in the food by cooking it thoroughly in high heat. You need to cook meat fully to ensure it reaches the recommended temperature.

Clean Fridge

You need to clean the fridge regularly to avoid bacterial contamination. So, wash the shelves, handles, and drawers with warm water and soap frequently to eliminate bacterial presence.

Keep It Cold

You need to keep the temperature cold in your fridge. While the bacteria causing listeriosis does not die in the cool temperature, its growth slows down. So, keeping the temperature of the fridge and freezer as suggested by the guidelines.

Guidelines For Pregnant Women/Weak Immune System

Pregnant women need to maintain caution and avoid all possible infection sources. When you observe the early signs of pregnancy, you have to skin foods that can cause infection. So, pregnant women and people with the weak immune system must take precautions with the following types of food items:

  • Avoid soft cheeses like brie, feta, blue cheese or Camembert as it can cause bacterial infection. Also, avoid Mexican-style cheeses unless the product packing claims it uses pasteurized milk to produce the item. For avoiding complications, eliminate queso fresco and queso Blanco cheese from your diet.
  • Avoid hot dogs and deli meats. Only use it if you are reheating it until they are steaming hot. Always keep the fluid present in the hot dog packages from your utensils, other foods or surfaces where you prepare food. Wash your hands after you handle these products to avoid contamination.
  • Pregnant women and people with a weak immune system must avoid eating refrigerated meat spreads. Only use shelf-stable or canned meat spread as you can store them at room temperature.
  • You can include smoked seafood that comes with the label as jerky, kippered, lox, and nova style. Cook them well to consume it without any issues. You can eat shelf-stable or canned smoked seafood.
  • Always cook sprouts thoroughly of any kind before consuming them. Eating raw or undercooked sprouts can increase the chances of infection.


In most cases, listeria infection is mild with little or no symptoms. So, the prognosis for the condition is excellent. But, people with increased risk of complications like the ones with the altered or impaired immune system can heal with appropriate therapy. With early medical intervention, patients with severe symptoms can get back to their life. Without proper medical treatment, the prognosis is poor. But, pregnant women and their unborn babies face a high risk of complications due to listeria infection. With prompt medical care, you can avoid severe problems.

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