Listeriosis is a cosmopolitan disease, as Listeria ubiquitous bacteria are widespread in the environment. These microorganisms are found, in particular, in soil, forages, surface waters and fecal material.
Man contracts listeriosis mainly through the consumption of heavily contaminated, raw or cooked foods . Contamination can affect various sectors of the food industry (eg meat, dairy, fish and vegetable products ready for consumption) both in terms of raw materials and environmental (for example: plants, refrigerators, work surfaces and surfaces) .
Although contaminated foods represent the main source of infection, other modes of transmission should not be underestimated, including vertical ( mother-child ). Contagion can also occur due to direct contact with infected animals (cattle, sheep and goats). A role in the spread of the disease seems to be played also by the ticks ; a correlation between the presence of Listeria in these arthropods and the onset of listeriosis in parasitized cattle has in fact been demonstrated.
The people most susceptible to Listeria infections are the elderly, pregnant women, newborns and people with immune system deficiencies. In immunocompromised individuals - for example, transplant recipients, cancer patients and AIDS patients - a minimal infectious charge is sufficient for the disease to occur.
