Illness is an unavoidable part of life. Not just humans but also animals, birds and plants fall sick. There are innumerable reasons behind illness. The reasons of sickness can be classified into a few groups. There was a time when science had not progressed much and people used to blame ghosts, spirits and black magic for illness. Even the wrath of divine powers used to be assumed as the reason of illness. According to the ancient Chinese medical theory the imbalance of the five natural elements causes illness. They also believe that we get energy for working from the flow of natural energy. When this energy flow gets stopped we fall severely ill.
The communicable diseases are caused by bacteria, virus and fungus. Infection can happen at any point of life even if you were vaccinated properly at childhood. Vaccination cannot save you from all sorts of infections. When the virus or bacteria attack our body our immune system attempts to fight them off but fail many times. From minor cold and cough to severe diseases like AIDS occur due to the inhabitation of some sort of virus or bacteria in our body.
The rising levels of pollution are also responsible for illness. Due to stress and lifestyle disorder we fall sick sometimes. The imbalance of hormones can cause diseases like diabetes and hyper thyroid. Tension can make your body parts stressed and cause the body parts become dysfunctional. Most heart diseases and high blood pressure is caused due to stress and tension. Bad eating and drinking habits also make our body organs damaged and lead to chronic illnesses. The reasons of all diseases have not been found yet but researches are being done for the same. A good diet and healthy lifestyle can be the answer to most diseases.