Watch: What is listeria?

RTÉ News​

24-07-2025

Amid a precautionary food recall of around 200 ready-to-heat meals linked to an extensive outbreak of listeria, here is a look at what the bacteria is and what its symptoms are.
What is listeria?
Listeria monocytogenes is a bacteria that can be found in many places like contaminated water and food, soil and sewerage.
How can people contract listeria?
A listeria infection - or listeriosis - is most-commonly caused by consuming food that has been contaminated with this bacteria.
Foods of most concern are those that do not require any further cooking or reheating such as chilled, ready to eat foods such as ready meals, soft cheeses and smoked fish.
Listeria can survive at freezing temperatures, according to food safety experts.
What are the symptoms of listeria infection?
Mild flu-like symptoms are common, as are gastrointestinal issues such as nausea, vomiting and diarrhoea.
In rare cases, the infection can be more severe, causing serious complications.
Some people are more vulnerable to listeria, including pregnant women, babies, people with weakened immune systems and the elderly.
The incubation period (time between initial infection and first symptoms appearing) is on average three weeks but can range between three to 70 days.
How is listeria diagnosed?
Listeria can be diagnosed with a blood test.
How to prevent getting listeria?
You can reduce the risk from infection by eating freshly cooked or freshly prepared foods and avoiding foods that could contain Listeria, according to Safe Food.
It also recommends washing all fruit and vegetables before you eat them, cooking food right through and serving while still hot, consuming open food within two days, and keeping raw and cooked foods separate.