What is Listeria?

Listeria is a genus of bacteria that is widespread in the environment and can be found in food. The best known species, Listeria monocytogenes, is a major pathogen that causes food poisoning. These bacteria can grow in a variety of conditions, including low temperatures, and therefore pose a particular risk to the food industry.

Emergence

Listeria can develop in a variety of environments, including soil, water and plants. In the food industry, they can be found in processed foods, raw milk and dairy products, raw meat and fish, and processed foods such as cold cuts and ready meals. Contamination can occur during processing, storage and transport.

Detection

Listeria are microscopic bacteria that are invisible to the naked eye. They are detected using microbiological tests and cultures. Contamination in food can often only be detected after symptoms of illness have appeared in humans. The symptoms of listeriosis include fever, muscle pain, nausea and diarrhoea.

Limit values

In Germany, strict food regulations govern the permitted quantities of listeria in food. Regulation (EC) No. 2073/2005 on microbiological criteria for foodstuffs sets limits for the presence of Listeria monocytogenes in various food categories. A zero tolerance limit applies to foods intended for infant consumption.

Dangers

Health: Listeria can cause serious infections, especially in pregnant women, newborns, older adults and people with weakened immune systems. The infection can lead to fever, muscle aches, nausea, diarrhoea and, in severe cases, meningitis and sepsis. Environment: Whilst Listeria itself does not represent a significant environmental burden, the control of contamination through the use of disinfectants can have a negative impact on the environment. Economic damage: Listeria contamination can lead to recalls, production losses and significant economic damage for food manufacturers. They can also significantly affect consumer confidence in product safety.