Pneumonia is an infection of the lungs that can be caused by many different microorganisms. These include viruses, bacteria, parasites, and fungi. Pneumonia occurs when an infectious organism causes inflammation in the lungs. The air sacs fill with liquid and pus. This means they can't deliver oxygen effectively to the blood vessels.
Pneumonia is a fairly common infection that affects people of all ages.
Some cases of pneumonia can be prevented by the pneumonia vaccine . Annual flu vaccines can prevent pneumonia from flu viruses. Diagnosis of pneumonia begins with a medical history and physical exam. A chest X-ray can confirm the diagnosis. Often a specific organism is not identified.