Members of the genus Listeria are ubiquitous and only one species is pathogenic. Listeria have been isolated from various food products including dairy products, meat, vegetables, and seafood, as well as from environmental samples taken, in particular, from food processing plants.

Listeria monocytogenes is the only species considered as pathogenic for humans. Listeriosis in humans may cause pathologies such as meningitis, septicaemia, encephalitis and abortions.

Groups at risk include pregnant women, neonates, immunocompromised patients, and the elderly. Listeria monocytogenes is widespread in the environment and is a potential risk when raw, partially processed and even some fermented food are consumed.