Should I worry about rats in the garden?

My parents have a large garden and it has rats. They live in a massive compost heap (I’m talking several meters high and wide, can’t easily be moved). We see them running around this time of year, taking apples and other fruit away with them.

They don’t come into the house or sheds etc so I’m not worried about that, but should I be worried about any diseases for us humans or my parents’ dog? They have a husky and she does catch and eat field mice, so it’s not a leap that she might catch and eat these rats.

If they are an issue, what can we do when removing the compost heap or poisoning them aren’t options?