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The listeriosis is an infection caused by the bacterium Listeria monocytogenes , which is part of the group of Gram positive bacilli; This can be found in a large selection of sites, such as sewage areas or domestic animals. However, the main source of contagion towards humans is the consumption of food infected with the bacteria . From the time the person eats this type of food until the disease develops, it can take up to six weeks, which makes it very difficult to find out which food was contaminated by the bacterium Listeria monocytogenes.

What is listeriosis?

Listeriosis is a serious infection caused by the Listeria monocytogenes germ. The form of contagion that occurs in practically 100% of cases is the consumption of contaminated food . Although anyone can get listeriosis, this disease mainly affects four population groups: pregnant women, newborn babies, the elderly, and people with weakened immune systems.

In the case of pregnant women, the disease is mild for future mothers; however, it causes serious damage to the fetus, and can even lead to fetal death.

As for the rest of the population groups, listeriosis can cause the infection of certain serious diseases of the bloodstream, which can lead to septicemia or encephalitis .

The vast majority of people with listeriosis require hospital admission. The current death rate is 20%.

Symptoms of listeriosis

This disease presents a wide range of symptoms, which vary greatly depending on the general health of each person. Generally, the warning signs that occur are fever and diarrhea ; two symptoms that also occur in conditions caused by other foodborne microbes.

The population groups most affected by listeriosis may have other symptoms. For pregnant women, some of the red flags are fatigue and muscle aches . In the vast majority of cases, women do not go to the doctor since they relate the symptoms to the gestation period. However, the infection can cause serious problems such as miscarriage, stillbirth and even premature delivery.

For the elderly and people with weakened immune systems , some of the most common symptoms are headache, stiff neck, loss of balance, and seizures.

Symptoms generally appear within three weeks of consuming the contaminated food.


The diagnosis of listeriosis is not always easy since in the vast majority of cases the symptoms are related to other diseases. In order to determine a definitive diagnosis of this disease, it is essential to identify the microorganism in a sample that is generally sterile; this is something that occurs in practically all infectious diseases.

If listeriosis generates sepsis , something very common in elderly people and / or with a weakened immune system, the most common is to take a blood sample, which is cultured so that the bacteria grow and, in this way, identify it.

If the disease caused by listeria has caused meningitis , the doctor should take a sample of the spinal fluid through a lumbar puncture . Once the sample is taken, it is cultured to detect the bacteria.

Treatment of listeriosis

Once listeriosis is diagnosed, this disease is treated with antibiotics , which are responsible for destroying the bacteria and preventing it from replicating. The most common treatment is a derivative of penicillin, called ampicillin; It does not destroy the bacteria in a direct way, but it does prevent it from replicating, which is enough to prevent the infection from spreading.

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In addition to taking antibiotics, it is important to treat certain symptoms of listeriosis. To control fever, the doctor prescribes antipyretics; if sepsis occurs, the usual treatment is the administration of oxygen; and if this disease has caused meningitis, corticosteroids are prescribed.

It is important to remember that survival from a listeria infection is directly related to an early diagnosis ; the later, the chances of survival drop significantly, especially in the most sensitive population groups.

Listeriosis outbreaks

Almost every year an outbreak of listeriosis occurs in some country in the world. However, in the vast majority of cases they go unnoticed, without causing great damage.

However, in 2016 and 2017 the worst listeriosis outbreak in history was experienced in South Africa , which left a total of 180 deaths and nearly 1,000 cases tested in the country, representing a mortality rate of 27%. The outbreak was triggered by a batch of contaminated food from Africa’s largest packaged food producer.

Listeria and food

Currently, listeria outbreaks are directly related to certain food products, especially dairy products, fruits and vegetables. We explain everything below.


It is estimated that soft cheeses made from unpasteurized milk are up to 135 times more likely to cause listeriosis than those made from pasteurized milk. The explanation is very simple: pasteurization kills listeria. Of course, if the cheeses with pasteurized milk are made in facilities that do not keep the minimum hygienic conditions, they can also transmit this disease.

Raw sprouted foods

This type of food requires adequate temperature and humidity conditions to grow, which are ideal for certain bacteria to grow, such as listeria. Therefore, it is advisable not to consume any type of sprouts such as raw or undercooked radish.


One of the fruits with which it is easier to get listeriosis is melon . Thus, it is worth taking into account a series of basic recommendations when consuming it. First of all, it is advisable to eat the melon immediately after it has been cut. Second, the melon should be kept in the fridge for a maximum of seven days. And third and last, you have to discard all those portions of melon that have been at room temperature for more than four hours.

Tips to avoid listeriosis infection

There are a number of tips that are worth taking into account to avoid the transmission of Listeria monocytogenes, especially in the population groups more sensitive to this bacterium.

  • It is important to prevent those people who are at higher risk of contracting the disease from handling food, whether at an industrial or domestic level.
  • When handling any type of food, it is essential to wash your hands very well as well as all the kitchen utensils that are going to be used. Hygiene measures are essential.
  • It is essential to consume all food cooked at high temperatures, preferably grilled or baked.
  • It is essential to wash fruits and vegetables very well before consuming them.
  • It is important to keep all dairy products in the refrigerator at a temperature below 5ºC.
  • If you belong to one of the sensitive population groups in relation to listeriosis, consult your doctor immediately if you have any of the following symptoms: headache, fever, muscle aches, nausea and vomiting.


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Hello Readers, I am Nikki Bella a Psychology student. I have always been concerned about human behavior and the mental processes that lead us to act and think the way we do. My collaboration as an editor in the psychology area of ​​Well Being Pole has allowed me to investigate further and expand my knowledge in the field of mental health; I have also acquired great knowledge about physical health and well-being, two fundamental bases that are directly related and are part of all mental health.

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