In my opinion, it DOES work, but its only a temporary solution. The Zapper did kill lots of nasty stuff, I saw it in the toliet every night. But, its just a band-aid solution. It does not address the core issues. In my case it was blockages in CHI caused by dental work and allergies. So you CAN zap to kill the nasty stuff in your body, but your bodies immune system should be handling it anyway.
So either you can zap for the rest of your life, or try to find out whats wrong with your body and fix your immune system.
After what I've been though, I'd have to say that parasites are more of a symptom then a cause. I think repairing the immune system and reversing allergies and blockages in CHI is a much better route to go. Along with a diet in foods that your body wants, with whatever safe anti- parasite foods and herbs you can eat as well.
I've seen evidence of this. My body "dumped" more parasites and toxic crap on its own in the 3 days following my surgery to fix the jaw cavitations, then it did after weeks of zapping. I also passed 2 kidney stones and "lost" pains I'd been having in my gut. Zapping never did that for me.
I've also found that simple foods like beets, onions, garlic, etc kill parasites almost as well as the herbs do. At least in my case.
Everyone is different, so it may be completely different for you.