The Listeria genus includes 10 species of gram-positive bacteria that are optional anaerobes. The main pathogen infecting humans is Listeria mocytogenes. This species is the most pathogenic of those that can be transmitted by food (mainly dairy, raw fruits and vegetables). Listeriosis is a relatively rare bacterial disease with a severe course. 20-30% of infections end in death. L. monocytogenes primarily attacks the central nervous system leading to meningitis and septicemia. The risk group includes people with decreased immunity, pregnant women, newborns and the elderly. In addition to humans, L. monocytogenes can infect other mammal species, including cattle, horses, pigs, hens, hares and guinea pigs.