David - I'm using the zapper frequencies around the head area with no undue negative affect so far as that's where the problem mostly lies so if I zapped on the legs, wrists and stomach upwards whatever worms are in the body tissues might well drive them upwards towards the head, that I would want to avoid, I want to drive them downwards if I can't kill them outright.
Yes there are body areas and tougher parasite species that can remain to dwell in the body and those who have escaped the frequency currents, where resistence is at its highest.
Herbs have not controlled or cleared, the same goes for the multiple long treatment courses of the multi anthelminthic meds, my long-term infection so zapping is now a singular option for me.