Listeriosis is an infectious but not contagious disease caused by the bacterium Listeria monocytogenes, far more common in domestics animals (domestic mammals and poultry), especially ruminants, than in human beings. It can also occur in feral animals—among others, game animals—as well as in poultry and other birds.

The causative bacterium lives in the soil and in poorly made silage, and is acquired by ingestion. It is not contagious; over the course of a 30-year observation period of sheep disease in Morocco, the disease only appeared in the late 2000s (decade) when feeding bag-ensiled corn became common.In Iceland, the disease is called "silage sickness".
Given a reference text about Listeriosis, tell me how how the bacterium is transfered into animals, and people.
Listeriosis is most often associated with animals but can also infect people and is primarily transferred by ingestion.