Can listeria develop on spoiled food that wasn't previously infected, or does it have to have already been present before the spoilage occurred?

Listeria. See you are pregnant. Listeriosis is a food borne illness caused by the listeria bacteria. The incidence of listeriosis in pregnancy is 12 per 100, 000. Thus it is a rare disease. Listeria is found commonly in nature. So it can be hard to avoid being exposed to it. Food could become cross contaminated in your kitchen. Wash your hands after you handle hot dogs. Avoid cross-contaminating fluid from.
It has to already. Have been present within the food or contaminated from outside source. It will not show up spontaneously, but food can be contaminated by accident without users knowing specifically whether it was contaminated or not. Hope that helps a little!