Years ago we lived in a... Less than ideal situation, where we had no power for the first year we lived there, and no plumbing for the entirety of our 3 year stay. In the winter that first year, we sort of accidentally created one on the wood stove, and I looked it up online when I went into town to see how long you could leave it going. It'd been three days, and we found the wiki article. Ended up keeping it for the entire winter until we weren't using the wood stove anymore (cooking outside once it was warm enough). It was good. It got old, but it was food, and that winter, that was the important part.

That's a good point. I guess I wouldn't want to keep one going myself.

But as a guest in someone's house that had one going indefinitely, it was exceptional. They looked at me funny when I asked what was in it so I just left it at that. I know at least some hunted animals and carrots were in it.

Above 60°C, the bacterias and fungi are killed. If you maintain the stew at 80°C, it will be okay.

All the bacteria are too busy fighting to supremacy amongst themselves to bother with infecting anything else.