Hi Adrienne.
I used to have a zapper myself. Regarding electrosensitivities - the instructions do recommend that patients with heart arrhythmias don't use a zapper. The whole process is very time-consuming. You hold an electrode in each hand for about 15 minutes and then have a 10 minute break and the swap hands and repeat. This goes on day after day. Each electrode is a 6" piece of 1" copper piping, which you have to wrap in a paper kitchen towel, soaked in a solution of sea salt. By the end of each session, the green residue on the copper (copper chloride) has to be removed to ensure optimal contact with the electrode. There are more efficient ways of removing parasites eg Bio-Ex Therapy, although for anyone who is not able to access other healing would almost certainly benefit from zapping. It is possible to feel the current in the electrodes, so it may not be suitable for anyone who has electrosensitivities.