I did some research and found out to my suprise, that even in very cold temps, listeria can grow, even in your fridge..it says the fridge needs to be below 34 degrees to stop it from growing, I'll paste below what I was reading.
Listeria monocytogenes can be found throughout the environment and in many foods. It is associated primarily with meat and animal products. It resists heat, salt, nitrite and acidity better than many organisms and can grow at temperatures as low as 34oF (1oC). Low storage temperatures slow, but do not stop growth. Commercial freezer temperatures of 0oF will stop L. monocytogenes from multiplying, but may not destroy it. Commercial pasteurization procedures for dairy products have been determined to be sufficient to destroy this organism. Proper cooking and reheating of foods will effectively control Listeria. The organism can colonize cracks, food-filled crevices, and inaccessible areas in food preparation and processing facilities and equipment. This presents a significant challenge to sanitation procedures.
Recent outbreaks of L. monocytogenes foodborne infections (listeriosis) have heightened concerns over its presence in foods. Its presence on a food does not change the taste or smell of the food. Foods implicated in outbreaks include soft (i.e. Latin-American white cheeses, Feta), and surface-ripened cheeses (i.e. Brie, Camembert--both domestic and imported), deli salads such as cole slaw, raw (unpasteurized) milk, turkey franks and other hot dogs, shrimp and (undercooked) chicken. Previously cooked, ready-to-eat foods requiring no further cooking are also of concern.
Who is at risk?
Most healthy people will not become ill from foods contaminated with this organism. Persons at increased risk include pregnant women (or more correctly, their fetus), organ transplant recipients, the elderly and those with immunosuppressive conditions such as cancer, renal disease, diabetes, AIDS, and conditions caused by corticosteroid use.
What are the symptoms?
The disease symptoms are variable and depend on the individual's susceptibility.
Symptoms may be limited to fever, fatigue, nausea, vomiting and diarrhea. Flu-like symptoms may occur 12 hours after eating L. monocytogenes contaminated food. Researchers are not sure how many L. monocytogenes organisms it takes to cause illness. Onset time probably depends on the health of the patient, the strain of L. monocytogenes and the amount of the bacteria ingested. However, these symptoms can precede a more serious illness.
The more serious cases of listeriosis may take one to six weeks to develop. These cases may result in meningitis (brain infections) and septicemia (bacteria in the bloodstream). Pregnant women with flu-like symptoms due to listeriosis are particularly at risk and may develop complications which can result in miscarriage, stillbirth, or septicemia or meningitis in the newborn. In older children and adults, complications usually involve the central nervous system and blood stream, but may include pneumonia and endocarditis (inflammation of the heart lining and valves). Skin contact of L. monocytogenes with a wound can cause localized abscesses or skin lesions.
Listeriosis can be positively diagnosed by culturing the organisms from blood or cerebrospinal fluid. The disease can be treated with antibiotic drugs such as penicillin or ampicillin.
