Question

how does the physician find that how disease caused

Answer 1

first to check out what disease is there by looking on the symptoms and then when the disease is discovered, and to which area the body is infected, for example when you get infection in lungs, you might stayed too close to a patient or you had inhaled dirty water[in case you fell in a pond] and if you get gut infection, mostly because you ate something expired or something too hot or cold etc. there are also many diseases which the physician cant explain how you get it too.