Basically, the human being is not only created by flesh body, in its ingredients where the particles of soil have processed there are halos or waves of light that is called light AURA and Astral body (JISM MISALI) by Scientist and spiritual people respectively.
The astral body always exists 9 inches above from the human body. The aura consists of different proportions and quantities of light. Human body basis on it. The human body always well balanced on if the astral body is perfect and always takes all the indications from whatever astral body give. Not only human being are beneficial from their astral or aura but all the creatures on the earth are fed by Astral light. Briefly, it would say that all the needs of human beings are inspired directly to this Aura or astral body than after send to the fleshy and bone body. for example, we see a man starving and eating bread, but infect if there is no requirement of hunger or thirst in the astral body, it would not transfer to normal(fleshy bone) body. Moreover, We dream and see different places of the world all the actions that we do such like flesh body is actually a movement of Aura(astral body) that perform actions without making the fleshy bone body as the medium. Remember, the dream is not the assumption or fictitious, it is also a real world as such as we say this world reality in our awakening hypothesis senses.
When Aura disconnects this body of soil all the particles get annihilate. This method of death or sort to say annihilate is not only for human but every living has to annihilate after its specific time. The time is specified when the aura will annihilate from the globe.
In the spiritual point of view, we can say that the astral body disengages its relation to this fleshy bone body and creates a new body in other world.
DISEASE
Aura is always active all the time in our life. One of the quality of aura is to protect the fleshy bone body until unless its death and always balance their enlightenment and waves. Actually, quantities of aura get imbalance as a result we call it a disease. So if we try to balance the aura our fleshy bone body becomes perfect and healthy.