A healthy mind and body is all what one desires from but there are some hindrances to healthy life called diseases. As the name suggests it is a state of having a discomfort (dis-ease) in a healthy body and mind. A disease is a condition in which the body functions work a little different from that of a normal body. There are different ways by which a body can get attracted towards the diseases. Most common of them are the infections caused by bacteria, virus, fungi etc. formed inside a host body. But as the medical has invented cure to every disease, it has done same for infections also. The immune system is responsible for resisting entry of any other agent inside the body by providing anti-bodies against the virus or bacteria entering the blood cells of the body. If the immune system fails in its task to prevent the entry of any outside agent, the virus enters the body and start reproducing itself causing ill-health.
The disease in which the virus, bacteria or any other agent carrying disease comes from any other unhealthy person is called contagiousness. These diseases are also called