Re: parasite's role?

This is an intereting question. I've already pondered on that myself. Parasites, cancer, common colds - they all appear for a reason. Nature is based on recycling principle, hence any decaying matter attracts either bacteria or parasites whose sole role is to deal with that stuff. It's true that after a parasite cleanse they can come back with a vengeance, but it's only true if you
1) don't correct the problem due to which they appeared in the first place
2) continue old lifestyle of bad eating and otherwise habits
Same is true in the spiritual world. Jesus said that if you expel the demon from the house and leave it empty and swept he'll come back with a dozen more. That's in my words. But the point as I see it is that if you remove the bad you have to replace it immediately with the good, otherwise you'll get 3 times the bad then you had the 1st time. Hope I'm making sense here.