It takes some real persistance to get Ascaris or tape worm with herbs, basically you have to keep throwing everything you can stand to swallow and even sort of function, to kill them off. Also a zapper helps, as does diatomacious earth.
From general reading about parasites, they all cyst up, or hide in a nice spot somewhere if conditions aren't favorable for them, and they can stay that way for years, until they hatch out. Clarkia is designed to get the cysts, if I remember my HC correctly, anyone jump in if I'm stuck on air head, please feel free.