you can't expell those that are living within the body's subcutaneous tissue/fat, they are not going to move after treatment conveniently towards the intestine, colon, nose, throat or any other orifice although scattering/migration can be felt, I've never had any leave through the skin pores as they are bigger in size than micro filaria nor did any exit from the butt except for once at the beginning of the infection, a large red worm about 10 inches, it was extremely lively when I pulled back the duvet, quite a shock it was and it was never felt exiting.
It is my view in systemic disseminated infestations only, there are no ways any one treatment could be proved conclusively to be near 100% effective if at all.
Even when migration or scattering is felt, for instance when the parasites' demise is in situ in the tissues the adults along with their varying stages of larvae, ova/eggs whether encysted or not, a herx might well be experienced, yes only might be - with symptoms of gross fatigue, nausea, low mental clarity, aches/pains, high temp, itching, swellings, rashes, disruptive stools with or without parasites, but that is not always the case particularly with systemic hyperinfections.
In my long experience of taking various herbs and medications herx's were never clear cut, yes I did feel die-off at times which felt horrible as described above to the point of not functioning but then the reproducing cycles along with the adults and their larvae were distinctly felt again which continued for months and years that followed and that was after several herx reactions.
Whether die-off is experienced, it is not on its own a conclusive factor that the treatment was successful, that's my opinion.