Listeriosis – A Killer on the Loose

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Listeriosis is a disease caused by the bacterium called Listeria monocytogenes (L. monocytogenes).  The recent Listeriosis outbreak in South Africa killed at least 180 people and infected almost 1000 others since January 2017.  It was the world’s worst recorded listeria outbreak.

The National Institute for Communicable Diseases eventually identified the culprits on 4 March 2018.  L. monocytogenes were found in ready-to-eat processed meats (polony and sausages), manufactured by two meat processing companies.

On 3 September 2018, the Health Minister, Aaron Mostoaledi officially announced the end of the outbreak.  The South African economy lost hundreds of millions and the meat processing industry took a big knock.

The outbreak might be over, but there could be severe ramifications for the companies concerned.  A double edge sword hangs over their heads.  Victims and family members of victims might launch a class action suit and/or possible Government fines imposed as per the South African Consumer Protection Act, No 68 of 2008.

Where Do You Find Listeria Monocytogenes Bacteria?

You find it in the environment, including soil, water, and many other environmental sources.  It also survives in the digestive systems of at least 37 species of mammals (both domestic and wild), birds (17 species identified), some species of fish and shellfish.  Did you know, up to 10% of humans might be intestinal carriers of the bacteria?

Listeria – Cow
Listeria Monocytogenes (Listeriosis) and Poultry

L. monocytogenes is common in the environment and livestock. This is the main reason why it is frequently found in vegetables and uncooked meat. L. monocytogenes is resistant to adverse conditions and can survive freezing, drying, high salinity and low heat.

Food Sources That Might Contain Listeria Monocytogenes Bacteria

These are only a few examples and you should take precaution when consuming raw, undercooked and under heated food products.  Rinse vegetables and fruit properly and remember to wash your hands before and after working with food.

Listeria Monocytogenes (Listeriosis) and Deli Products
Cold Meats and Some Cheeses
  • Unpasteurized (raw) milk and dairy products
  • Ready-to-eat deli meats and hot dogs
  • Soft cheese made with unpasteurized milk, such as Feta, Brie, queso fresco, Camembert
  • Refrigerated meat spreads and pâtés
  • Refrigerated smoked seafood
  • Raw sprouts

In recent years soft-ripened cheeses and under pasteurized milk have caused several cases of infection, but during the recent listeriosis outbreak in South Africa, ready-to-eat (RTE) meat (cold meats) and poultry products were the main culprits.

Who is at Risk?

Pregnant women and the elderly is more susceptible to Listeriosis
Pregnant Women and the Elderly

L. monocytogenes is especially pathogenic to high-risk human populations such as:

  • newborns
  • pregnant women
  • the elderly
  • people with weakened immune systems, such as persons immunocompromised by anticancer drugs, graft-suppression therapy and AIDS

Other conditions that may increase susceptibility to Listeriosis are:

  • diabetes
  • cirrhosis
  • asthma
  • ulcerative colitis
  • end-stage renal disease
  • liver disease
  • alcoholism

Healthy people are generally at low risk of contracting L. monocytogenes-related illnesses, but heavily contaminated food can make any person susceptible to infection.

Although listeriosis infections are relatively uncommon, it is a potentially fatal disease.  Frequent spontaneous abortions do occur in pregnant women who are infected with the bacteria.

Even though the symptoms may be relatively mild in the mother, the infection may be transferred to the foetus, causing serious illness or foetal death.

The Symptoms of Listeriosis

Symptoms of L. monocytogenes may include:

  • fever
  • stiff neck
  • confusion
  • weakness
  • vomiting sometimes preceded by diarrhea
  • meningitis
  • encephalitis
  • septicaemia
  • spontaneous abortion
  • stillbirth
  • influenza-like symptoms

The onset of the disease can occur anywhere from a few days up to 6 weeks after the ingestion of L. monocytogenes bacteria.  The symptoms last from a few days to several weeks.

Listeriosis is clinically defined when the bacterium is isolated from blood, cerebrospinal fluid, or an otherwise normally sterile site (such as the placenta).

The Responsibilities of Food Handling Organisations

The South African Listeriosis outbreak has resulted in an unprecedented public health risk.  This could have been easily avoided by the industry.  Food handling organisations have to ensure that steps are taken at all levels of production to prevent contamination of meat products by Listeria monocytogenes.

While this is a difficult task, given the fact that L. monocytogenes is so widespread in the environment, the recent outbreak has shown that it is a necessary precaution.

Food-processing operations need to make every effort to prevent contamination by L. monocytogenes in raw, unprocessed foods and recontamination in precooked, RTE finished products.

Due to foodborne illness associated with L. monocytogenes in meat and poultry products, the USDA has issued a zero-tolerance policy for the organism in RTE foods.

How Do You Effectively Control Listeria Monocytogenes in Your Organisation?

Effective control of L. monocytogenes is challenging.  It requires intensive management and extensive resources.

This is usually in the form of effective HACCP and Food Safety Management Systems that ensure that food production facilities ascribe to the highest food safety standards.

Even though the risk of contracting listeriosis is relatively low, the consequences are devastating for both the consumer and the processor when it does occur.

The presence of L. monocytogenes in raw ingredients emphasizes the importance of adequate cooking (thermal processing) to destroy the organism.

Preventing the spread of Listeriosis starts with proper housekeeping and cleaning. Factory employees need to ensure they maintain good hygiene practices all the time. Factories need to be thoroughly cleaned and disinfected. Proper verification systems including taking micro swabs, visual observation, etc become necessary to ensure the effectiveness and efficiency of cleaning.

Well Trained Staff Can Help Prevention

Employee training also plays an important role in controlling contamination problems.  Employees must understand the organism, observe basic sanitation principles, and gain the same sense of personal responsibility exhibited by management and regulatory officials.

ASC Consultants has a wide range of training modules available to assist employees in understanding Listeriosis and its preventative measures.

You are welcome to Contact Us for more information.


Listeria monocytogenes bacteria are common in the environment and we will never be able to avoid it, but we can prevent Listeriosis.  Good personal hygiene practices and taking the necessary food safety measurements in the workplace will make a difference.

Awareness is key!

You are welcome to drop us a comment below.  We love to hear from our website visitors!

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8 thoughts on “Listeriosis – A Killer on the Loose”

  1. This article made me understand Listeriosis is a serious infection caused by the germ that  usually make people become after eating contaminated food. It’s unfortunate that this disease primarily affects pregnant women, newborns, older adults, and people with weakened immune systems, but my curiosity is me wanting to know what type of food does carry listeriosis easily and the duration of time ?

  2. I find it really scary that one can catch such food born bacteria even from innocent seeming things like pre-packaged salads.  When we can’t rely on proper handling in the processing business it becomes our job at home to do what we can – although sometimes that isn’t enough.

    One of the main culprits can be your own cutting boards and counters.  Even clean seeming dish rags and especially the dreaded kitchen sponge can simply smear bacteria around.  One must be so very careful to use lots of soap or sanitizer in cleaning both the food and anything that comes in contact with it.  Just a while ago a brand of pre-made salad had to be pulled from the shelves due to contamination.  You just never know what is in or on your food.

  3. Hallo there, 

    I have been hearing about listeriosis but never took much keen on it until I read somewhere that it is one of the worst killer health conditions. 

    I see that it is readily found in refrigerated meat spreads and pates as well as smoked seafoods. There was a story in our country where these kinds of foods were contaminated with sodium to keep them fresh for a long time and it got many people worried, including myself.

    Now I’m wondering, since I was a huge fan of the foods before the story came up, is there any chance I increased the risks of getting the condition if truly the foods were contaminated?

  4. Listeriosisis a very scary  thing. I have seen outbreaks of this in many areas of the world on the news. It is really bad and I feel that people need to understand what it is about and how to prevent it . if proper measures were put in place, then people in south Africa wouldn’t have died due to the listeria bacteria. I’m glad that proper measures are being put in place to curb this. The symptoms are really similar to some other diseases so it might be hard to know if it is listeria bacteria or not. Over all this post is really educative one.

  5. Hi, your post is unique and educating, discussing in your post about the bacteria named Listeriosis is really informative.

    i really appreciate post like this that gives awareness to health related matters, it caught my attention when I was reading the list of food that can be effected through them, I notice most of foods are involve.

    the best solution is cleanliness when handling foods and proper cooking even though those with high immunes can not be effected but we should not forget that we grow every day and the more we grow the more our immunes are getting weak.

    i will he sharing your post for my friends to also benefit from the information in your post through my social media.

  6. Lack of proper food handling and personal hygiene not being prioritized has led to many outbreak of listeria. I think there’s need for sensitization especially to people that are more susceptible to it—elderly and the pregnant women. This post has done justice to this a lot and has also given precautions as to the major food options to look out for on order to keep listeriosis in check. I will be more than glad to share this out to all my social platforms so that more people can know of this

  7. Listeria outbreaks are very scary. There have been many Listeria outbreaks reported worldwide every year. Most of these outbreaks are mainly due to the lack of proper food handling practices. This is a very informative article about Listeriosis. It is important to know what Listeria is and whom is most susceptible to contracting this potentially deadly disease. I am very careful when handling and preparing food and do not take any chances. If I have any doubts about any food products I don’t buy it or it gets tossed.

    • Hi Monika,
      Thank you very much for having a look at our post. Good food handling practices are not only the manufacturer’s responsibility, but the consumer should also be vigilant when preparing and cooking food.


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