This is safefood's Listeria awareness week. So why are we trying increase awareness of this particular bacterium? 

Well, although the disease caused by Listeria (called Listeriosis) is not a common illness, listeriosis can be very serious for vulnerable groups. It has a high hospitalisation and fatality rate compared to infections with other food poisoning bacteria.
Between 2015 and 2018 there was an outbreak of Listeria across the EU linked to contaminated frozen sweetcorn that resulted in 47 cases including nine deaths. It is thought many of the cases were caused by people were using frozen sweetcorn without cooking fully or cooking at all (just defrosting) in salads.  Most frozen vegetables, including sweetcorn, spinach etc. will need to be fully cooked before you can use them in salads and smoothies. You should always follow the manufacturer’s instructions on all frozen vegetables, fruits and herbs. 

So what is Listeriosis and who is at risk?

Listeriosis is a foodborne disease that is caused by the eating raw, chilled, and ready-to-eat foods that are contaminated with Listeria monocytogenes (Listeria). While anyone can become ill from eating food contaminated by Listeria, those most at risk include those in vulnerable groups such as the elderly, pregnant women and their unborn babies, newborn babies and people with weakened immune systems.  In healthy adults, Listeria can cause a flu-like illness. However, it can cause very serious illness in vulnerable groups.
Illustration of Listeria bacteria

So how does Listeria get into our food?

Listeria is common in the environment and can be found in soil and water and because of this, a wide range of foods have been associated with the spread of infection. Vegetables can become contaminated from the soil or from manure.  Animals can carry Listeria without appearing ill, and meat or dairy products from these animals can be contaminated.
Listeria can also be found in food processing environments therefore foods may also be contaminated after processing, e.g. cheese or cooked meats.  Foods most commonly associated with infection are those that do not require any further cooking or reheating such as chilled, ready-to-eat foods including: soft cheeses including those ripened by mould, smoked fish, cooked sliced meats, cured meats, paté from meat, vegetables or fish, pre-packed salads and sandwiches and pre-cooked shellfish (sold as ready-to-eat).

What you can do to avoid Listeria?

To reduce the risk of Listeria when preparing food at home, it is important to:
  • Clean: Wash all fruit, vegetables and salad fully before you eat them.
  • Cook: Cook or reheat foods until they are piping hot all the way through and serve it when it is still very hot. Ensure that you follow manufacturer's instructions in the preparation of all foods.  
  • Chill: Make sure that your fridge is at 5°C or below. Put chilled food in the fridge straight away.
  • Check: Throw out food that has passed the ‘use by’ date, and if the food packet has been opened, use within 2 days.
  • Separate: Keep cooked food and raw food away from each other.
Please see the following links on Listeria or Pregnancy and listeria
Posted: 18/11/2019 11:56:54 by Mairead McCann

About Me

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Mairead McCann
I am Technical Executive in Food Science with safefood. I’m a food microbiologist and my work involves research into food safety and addressing queries on a range of food hygiene and safety issues. I live in County Cork although I am originally from County Down (where the Mountains of Mourne sweep down to sea :-). In my free time I love to keep fit, catch up with friends and family, plan holidays and nice weekends away and eating out with my husband.