Pneumonia is different in this way from acute bronchitis, which is another disease that can cause fever, cough, chest pain, and shortness of breath. Signs of pneumonia caused by bacteria usually come on more quickly than pneumonia caused by virus. Germs are spread both by aerosolized droplets that you breathe in (such as from a sneeze), and through body fluids left on surfaces like counter tops and door handles.
Prior to the discovery of antibiotics, one-third of all people who developed pneumonia subsequently died from the infection. The elderly are especially at risk of getting seriously ill and dying from this disease. Some causes of pneumonia are associated with classic, but non-specific, clinical characteristics. An inhaled infectious organism must bypass the host’s normal nonimmune and immune defense mechanisms in order to cause pneumonia.