The Centers for Disease Control and Prevention (CDC), has issued a warning especially to those over 50 to reheat their cold meat before consuming as a way to prevent listeriosis. It is important that the meat be heated to at least 165 degrees.
Listeria may not be as common as Salmonella or E.Coli but is lethal. The CDC recommends that any opened pack of sliced meat should be chucked out within 5 days.
Cold meat in the fridge is ideal for the bacterium, Listeria monocytogenes , to reproduce.
Listeria needs urgent medical attention as it can turn life threatening in certain cases.
Source-Medindia