- Listeriosis is caused by a type of bacteria called Listeria monocytogenes (listeria) and is mainly spread through contaminated food.
- Listeria is widespread throughout the environment and can be found in soil, wood, decaying vegetation and water.
- Unlike most other types of bacteria, listeria can survive and often multiply in temperatures below 5ºC (41ºF). Therefore, listeria can still grow to potentially harmful levels in food stored in a fridge.
- Listeria cannot multiply in temperatures below 0ºC (32ºF), but freezing food doesn't necessarily kill all listeria bacteria.
- Listeria can be removed by cooking food thoroughly or, in the case of dairy products, pasteurising it (a heat treatment designed to kill bacteria).
More top news
Father of drowned Syrian boy Alan Kurdi says he is comforted by impact of his son's death, as hia family is reportedly accepted by Canada.
A year ago the International Court of Justice ruled that Japan's decades-old whale hunt in the Antarctic should stop.
Shadow chancellor John McDonnell has backed a free vote for MPs on the issue.