I belive the reason they didn't bother trying porxies is because the issue has absolutely nothing to do with tempering... rather it seemed to me to be more like an extreme alergic reaction, or a lack of resistance to lightning aether making them very susceptible to it's effects, so as long as the afflicted stay in a region with strong lightning aether, there is nothing that can be done, even if they do relieve the symptoms the sickness would still remains and they would soon relapse anyways...