Listeria monocytogenes

Listeria monocytogenes (listeria) is a bacterium that causes an illness called listeriosis. Cases of foodborne illness from listeria are rare, but can involve serious symptoms and even death in certain groups of people. These include:

  • people with weakened immune systems, such as those suffering from cancer
  • pregnant women and their unborn babies
  • newborn babies
  • elderly people

The types of food listeria can be found in

Listeria is widespread in the environment and can contaminate a wide range of foods. It is of most concern in chilled ready-to-eat foods that do not require further cooking or reheating, such as:

  • cooked sliced meats
  • cured meats
  • smoked fish
  • cooked shellfish
  • blue veined and mould-ripened soft cheeses
  • pate
  • pre-prepared sandwiches and salads

What you can do to avoid listeria

To reduce the risk of listeria when preparing food at home, it’s important to:

  • keep raw and ready-to-eat foods separate to avoid cross-contamination
  • wash fruit and vegetables thoroughly
  • keep chilled ready-to-eat foods cold – make sure your fridge is working properly and is set to 5⁰C or below
  • always use foods by their use-by date
  • follow the storage instructions on the label and use opened foods within two days unless instructions on the packaging say otherwise
  • ready-to-eat food must be eaten within four hours of being taken out of the fridge
  • cook or reheat foods until they are piping hot right through
  • ensure that you follow manufacturer’s instructions in the preparation of all foods


Foodborne bacteria

Foodborne bacteria live in the gut of many farm animals. During rearing, slaughter and processing it can be transferred into:

  • meat
  • eggs
  • poultry
  • milk

Other foods like green vegetables, fruit and shellfish can become contaminated through contact with animal and human faeces. For example, from manure used to improve soil fertility or sewage in water.

Foodborne bacteria can be spread by cross-contamination. For example, if raw and cooked foods are stored together, bacteria can spread from the raw food to the cooked food.

Some foodborne bacteria can also be spread from pets to people and from person to person through poor hygiene. This includes things like failing to wash your hands properly after going to the toilet or after handling pets.

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Hi everyone,

I am a new member of this forum. Saw this post about listeria, any thoughts on listeria’s presence in raw wheat flour? Quite uncommon as wheat flour doesnt support the growth of listeria due to its low water activity. Would this pose as a food safety concern even if the percentage of the flour in the ingredient list is <5% and it is getting process e.g.heat treatment during the manufacturing process?

Looking forward to hear your thoughts.

Thank you!