Our true nature is timeless, here and now. The ultimate root of all disease is living out of alignment with nature, which is beingness, or Tao, or Buddha mind, or Christ consciousness, or whatever you may wish to call it. Various disease processes to which humans have assigned labels, such as cancer, AIDS, Alzheimer's, bipolar disorder, etc. A recurrent challenge in my own healing process, and as a guide for others, is maintaining a healthy balance between spiritual and physiological perspectives of healing. To say to those with cancer or AIDS that all they really need to heal is faith in a higher power, or to let go into the present moment may be true, but not very skillful.
Health hazards are everywhere.
If one assumes spiritual evolution as the goal of the human life, then the relative freedom and stability of a healthy human form is a precious vehicle through which we evolve. Preventive and emergency medicine keep the spiritual vehicle, the human body-mind, on the path. The assumption that when we die we automatically get another human body-mind is a big one, and even if we do, perhaps our circumstances will not be quite so fortunate as they are now. Simultaneously living aligned with spiritual purpose and engaging in the relative world is the knife-edge ridgeline we walk. Refining this skillful balancing to ever-higher levels requires a mind with a vast range of awareness, and infinite sensitivity to context and vibration.