Introduction

What is listeriosis?

Listeriosis is a kind of a serious infection caused by a harmful bacterium known as Listeria Monocytogenes (LM).

Overview

Listeriosis is a kind of life-threatening infection which is caused by a harmful bacterium called Listeria Monocytogenes (LM), and this bacteria is most commonly found in frozen food, packaged meats, and unpasteurized milk or dairy products made up of unpasteurized milk.^1,2

There is research-based evidence which proves that listeriosis is one of the top three fatal causes associated with food-related health complications. The number of patients who need to be taken to hospital is the highest for Listeriosis compared to other bacterial infections, with 94% of cases being hospitalisations and the death rate is as high as 20%.³

No symptoms actually appear in most of the cases as far as the initial phase is concerned.^{2, 4} However, there are a few symptoms which can be seen after a few days, which include:

• Rise in body temperature
• Chills
• Headache
• Pain related to muscles
• Upset stomach
• Neck becomes hard to move
• Patient feels unsteady

Listeriosis attacks people over the age of 65 or with weakened immune systems. Pregnant people are at high risk of getting caught by listeriosis, and the foetus can also come under the listeriosis attack. In fact, a child from an infected mother might not be safe even after birth.¹

Treatment of listeriosis depends on the severity of the condition or the complications associated with listeriosis.^1,5

Complications associated with listeriosis

Listeriosis threatens the life of the patients and this is because of the issues that occur as listeriosis stays for a long time period.

Those complications are infection of the protecting layer around the brain and spinal cord, and brain tissues also get infected due to listeriosis.

There are few cases in which pus filling has been observed in the brain region. The inner lining of the heart is also found infected among the listeriosis patients.

There is a fluid found in certain body joints to reduce the friction during the movement of the bones sharing the joint, that fluid has been found to be affected along with surrounding tissues.

Infection of the bone is another problem associated with listeriosis, and few other kinds of skin infections beneath the layers of the skin and on the surface do take place

Major complications associated with listeriosis are discussed here in detail:⁶

Blood infection

The complication which is the most common among all related to listeriosis is blood infection (medically known as septicemia). 

In a study data, LM was found to be responsible for causing blood infection in 46% of the total listeriosis cases.⁷

LM attacks the sites which are responsible for the release of the special substances in the human body that fight against disease-causing agents. Once it reaches the liver it enters the blood circulation.

Listeriosis affects the body in such a way that the body starts releasing certain chemicals which support the bacterium to survive and allow it to move to the adjacent cells, and this is how it spreads in the body.

During pregnancy, the mother transmits the blood infection to their child either from their own blood infection or there may be an infection in the area around the vagina or anus, which further gets transmitted through the vagina.

Foetuses lack protective immune systems, thus this helps listeriosis to develop easily. Decreased movement of the gastrointestinal tract also increases the risk of listeriosis spread.

In older patients, listeriosis is found to be attacking the patient with an already existing medical condition, which affects the immunity in a negative manner. These conditions are either a few types of cancers or long-term diseases responsible for worsening the defence mechanism of the body.

Flu-like symptoms and, in a few cases, symptoms related to the urinary system or stomach are seen as well.

Patients with long-term diseases, which affect the immune system have been found to be reporting back pain issues with LM infection for over a year-long period.⁷

An example of a typical case-related blood infection due to listeriosis was observed when an 80-year-old man suffering from diarrhoea was hospitalised for eating a 5-month-old fridge-stored mushroom.⁸

Meningitis

As discussed, the listeriosis-causing bacterium LM attacks persons with compromised defence systems. It mostly enters the body with frozen food, escapes the acid in the stomach and then enters the small intestine.

Listeriosis can become life-threatening as it can affect the membrane which surrounds and supports the brain. Signs and symptoms of various kinds are found during meningitis due to listeriosis.

These resemble the normal flu symptoms like headaches, vomiting or loose stools with increased frequency, to those which are of extreme seriousness like vision impairment (seeing double), and high-intensity headaches (especially at the front side with a 10/10 intensity).

Listeriosis attacks children with weak immune systems, so it is not so commonly found among children with good health.⁹

Encephalitis

There are other cases in which not only the outer membrane of the brain but the brain itself gets affected, and this condition is called encephalitis.

Once LM enters the blood circulation, the nerve which connects other parts of the face with the brain, helps the bacterium in attacking the brain.

Inflammation of the intestine is the diagnostic marker. This helps the bacterium to attack the nerves connected with the brain and encephalitis occurs.

Its spread from one part of the brain to the other parts can easily take place once it enters the brain. There are many pus-filled structures have also been observed.¹⁰

Death of the baby before birth

The mechanism of the bacterium spread is similar as mentioned in the blood infection section earlier. In addition, a pregnant person is more prone to get infected with LM with chances increasing by 18-fold. .

This is mainly due to the decrease in the number of cells that are responsible for fighting against the diseases. The direction of the placenta and the ability to stay for a long time in the space between the cells allow the LM to rush into the blood of the foetus.

Symptoms in pregnancy are somewhat similar to flu, like vomiting, diarrhoea, and muscle pain. There are other types of disorders observed too, when a pregnant person gets infected with LM. Fever was reported by 75% of the total number of pregnant people under observation.

Shivering and high fever are very common symptoms that are also associated with food poisoning. Breathing problems are another complication observed. Infection of the blood can certainly stop the functionality of the other body organs. 

Besides, the bacterium LM is well equipped to hide in the placenta, which actually makes the diagnosis and treatment difficult.

In pregnancy, the movement of the child in the womb is decreased, the uterus contracts with significant frequency, and there is pain in the abdomen and bleeding through the vagina, as signs of premature birth can also be sensed.

The digestive tract of the foetus also gets altered, and few of the other organs are found to become enlarged. Around 2/3 of the cases in which a child got infected in the first trimester of the pregnancy, the abortion route was considered.

However, 1/4 of the child infection cases were diagnosed in the second or the third trimester, and those cases resulted in stillbirth (when a child dies after the 28 months of pregnancy and before or during birth).⁵

Another fact, LM is found responsible for affecting women of Latin American origin more than other women, this is because of the traditional homemade soft cheese prepared from unpasteurized milk.⁴

An important observation to be noted in the studies is that the LM infection leads to different complications in pregnancy, however, death of the pregnant person is rare.⁵

Summary

Listeriosis is a serious infection caused by a harmful bacterium known as Listeria Monocytogenes (LM). LM grows on the frozen food articles and then attacks its consumers.

Symptoms are similar to the flu i.e. fever, headache, chills, and upset stomach. It is important to know that it attacks people with weak immune systems, and infection can spread from mother to foetus leading to pregnancy complications.

Due to its severe complications, it is one of the worst three food related infections and causes hospitalisation in around 95% of cases. Every 5th person infected with listeriosis dies.

Many kinds of complications are associated with listeriosis, and blood infection, meningitis, encephalitis, and stillbirth are the most dreadful.

LM attacks the intestine first, then the defence system. Once it enters the liver, entry into blood circulation is inevitable. From there it spreads all over the body.

It is treated with different kinds of medicines which depend on the severity of the condition. 

Death of a mother is rare during pregnancy, if they get infected with listeriosis.