I've used Hulda's Zapper and I can't recommend it. It is intended to kill foreign microbes with an electrical current and it may do this to some extent but there are much better devices.
Among the better known are Dr. Bob Beck's gizmos which include the blood electrification unit, magnetic pulse generator, water ozonator, which many people sell. Check out http://www.sotainstruments.com/
This whole electrotherapy business was inspired by Royal Rife's frequency machines. It's hard to find anything very useful. See http://www.bioharmonics.com/ for one view.
There are also herbal approaches to getting rid of parasites, such as paragone. If you have a fungal infection, check out the product Threelac.
These are not going to be helpful for autism.
