1 Answer

How do people "catch pneumonia"?

Some cases of pneumonia are contracted by breathing in small droplets that contain the organisms that can cause pneumonia. These droplets get into the air when a person infected with these germs coughs or sneezes. In other cases, pneumonia is caused when bacteria or viruses that are normally present in the mouth, throat, or nose inadvertently enter the lung. During sleep, it is quite common for people to aspirate secretions from the mouth, throat, or nose. Normally, the body's reflex response (coughing back up the secretions) and their immune system will prevent the aspirated organisms from causing pneumonia. However, if a person is in a weakened condition from another illness, a severe pneumonia can develop. People with recent viral infections, lung disease, heart disease, and swallowing problems, as well as alcoholics, drug users, and those who have suffered a stroke or seizure are at higher risk for developing pneumonia than the general population. As we age, our swallowing mechanism can become impaired as does our immune system. These factors, along with some of the negative side effects of medications, increase the risk for pneumonia in the elderly.

Once organisms enter the lungs, they usually settle in the air sacs and passages of the lung where they rapidly grow in number. This area of the lung then becomes filled with fluid and pus (the body's inflammatory cells) as the body attempts to fight off the infection.

http://www.medicinenet.com/pneumonia/article.htm