Just because you call something a parasite doesn't make it bad for you. It might be bad, or good, or some of both, or depend on other factors at different times.
If you count cells and genes instead of mass, every human hosts more non-human life than human. Call them parasites and delete them and die.
If you count cells and genes instead of mass, every human hosts more non-human life than human. Call them parasites and delete them and die.