I think you could take your musings to the parasite Debate Forum. Remember that there are a large variety of parasites, all the way from viruses to fleas and leeches. Only the higher of these organisms have rudimentary nervous systems, they don't think as we humans and higher animals do, they respond to stimuli. Some scientists think that our seemingly benign parasites don't need to be killed as they may be doing us more good than harm. Other scientists, Dr. Hulda Clark was one, think that killing off as many parasites as possible to be the best course.