Pneumonia is an inflammatory disease of the lungs. It is a special inflammation of the parenchyma of the lungs . Pneumonia is usually caused by a virus , bacterial or fungal infection. Mild or mild pneumonia can be life-threatening. There is also the possibility of getting the flu from pneumonia. Pneumonia is more common in older people who have had a chronic illness or who have a weakened immune system. However, pneumonia can also occur in young , young , and healthy people. [3] [4] Infection with streptococcus-like bacteria or respiratory syncytial virus (RSV) in the lungs causes the lungs to swell , filling up with pus or fluid , which absorbs oxygen. Gives. Then there is inflammation in the lungs.