Everything in nature has been put there for a reason, nothing in Nature is meaningless. Is the human race not part of the animal kingdom (mammal to be exact) are we not subject to the same laws of nature as other animals?
Every so-called “disease” is part of a Significant Biological Special Program of Nature (SBS), a program put in place for our survival, to assist the organism (you and me) in resolving the actual conflict situation to be better prepared the next time thereby insuring our safety and survival.