Currently, there are over 16 million individuals infected with this disease (Chagas disease) in South America and some have managed to migrate to the US. This parasite has been transmitted by transfusions as well as by its natural vectors. I do not know if that might help you determine the source of your illness.
What zapper are you using? Are you using augmentation footpads? When using ParaZapper CCa along with the augmentation footpads, we have found that a system of 14 minutes on and 20 minutes off throughout the day produces best results. Continuous zapping does not appear to work as well. This is based on user responses to surveys.
Let us know what zapper you are using and how good your results are.