[quote]
I'm using the zapper frequencies around the head area with no undue negative affect so far
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Of course you have no side effects if you use the weak zapper of Parazapper. Weak output voltage + weak allowed intensity = no side effects (and not much killing effect)
Maybe if the kind of parasitic worms you are infected with is weak, you will manage to kill the adult and all larveas. I hope for you.
Else you will need a more powerfull zapper and a smart positionning of several electrodes.