Honestly, I don't believe this. I think a happy worm sits nice and quiet and doesn't get noticed. Then you throw irritating herbs at it and it starts wiggling. So suddenly you FEEL it all over your body. But I doubt the herbs made it scatter. The worm is probably a systemic worm that was ALREADY all over your body, just sitting quiet and happy, sucking your life away.
That's my theory anyway. If a worm can survive in a part of your body, why would it not go there to begin with? There certainly are no lack of babies to spread around from one end of your body to the other. They are probably fighting for space. If a worm can't survive in a part of your body, it will die as soon as it gets there.
The larvae are usually transported via blood or lymph fluid which goes over your whole body. If the larvae ends up in a leg and as it develops, it can't survive in the leg, it does. If it can survive in the leg, then there it stays, in the leg. But you didn't notice it arrive because it was only larvae then. Now it is an adult worm and you throw herbs at it. It wiggles. And you are shocked and thing the herbs drove it there.