they don't move' - when you say they might be happy feeding on whatever they like including the copper so they don't move - you say further for a treatment to be considered effective, it must produce die-off, 'lack of movement'? Movement or not, there is no sure way of telling.
Please re-read my post :
I say that for a treatment to be considered effective against parasites, it must produce die off, lack of movement of the worms, lack of pricks sensations, lack of scratches sensations may be an indicator, but you must also expell them somehow, whether it is in the feces, the urine, the phlegm from that come from the nose or/and mouth.
I clearly explain that lack of movement should not be considered as a success if there is no die off after the treatment.
But if you do a treatment that produces a great die off, then if you don't feel any annoying symptoms, i think that's a good sign. However i agree that it is important to do another treatment from time to time to kill the remaining larvaes.