Pneumonia is an infection of one or both lungs. Caused by viruses, bacteria, or other germs, this contagious illness can be serious -- in some cases, even life-threatening. Some of the risk factors for this condition include being over the age of 65, smoking, having diabetes or other chronic health problems, and having a weak immune system.
People who are at risk can take steps to help prevent an infection by not smoking, washing hands frequently, and following a healthy diet. Several vaccines also are available to prevent certain types of pneumonia.
(Click Pneumonia for a more in-depth look at this condition and its causes, symptoms, diagnosis, and treatment. You can also click any of the links in the box to the right for specific information.)