Animals can be carriers.
It resides on food contact surfaces.
It has been found in uncooked meats, uncooked vegetables, fruit such as cantaloupes, milk (both pasteurized and unpasteurized), foods made from milk (ditto), and processed foods.
Pasteurization and sufficient cooking kill listeria. However, contamination may occur after cooking and before packaging.
For example, meat-processing plants producing ready-to-eat foods, such as hot dogs and deli meats, must follow extensive sanitation policies and procedures to prevent contamination.
Listeria is responsible for Listeria monocytogenes infection or listeriosis, a rare but potentially lethal food-borne infection. The case fatality rate for those with a severe form of infection is 20%.
Although listeriosis has low infectivity, it is hardy and can grow in temperatures from 4 °C (39.2 °F), the temperature of a refrigerator, to 37 °C (98.6 °F), the body’s internal temperature.
Listeriosis is most prevalent in the elderly, pregnant mothers, and AIDS patients.
Preventing Listeria Contamination in Food
Preventing listeriosis as a food illness requires effective sanitation of food contact surfaces. Alcohol is an effective topical sanitizer. Quaternary ammonium can be used in conjunction with alcohol as a food-contact safe sanitizer with increased duration of the sanitizing action.
The cheese was ricotta salata, a salty white cheese made from pasteurized sheep’s milk.
Government Lies By Omission on Listeria Site
The gov is lying on this page about listeria. It says pasteurization kills it. It does. The page leaves out the fact that listeria is found on foods after pasteurization. Pasteurization may kill what is there, but this bacteria is airborne. It can attach and contaminate foods at any point between soil and plate. Even in a person’s home. Even in a test lab.
Sources: Wikipedia | CDC.gov | Food Safety.gov