Viruses attack the lining of the bronchial tree, causing damage. As your body fights back against these viruses, more swelling occurs and more mucus is made. Even though your body kills off the viruses, it takes time for your body to repair the damage caused by the infection. During this time, you may continue to cough and wheeze. Anything that causes further damage to the bronchial tree, such as cigarette smoking, will lengthen the time it takes for you to get better.
Acute bronchitis is spread from person to person by coughing.
The viruses that cause the infection are sprayed into the air or onto people's hands when they cough. You can catch acute bronchitis if you breathe in the viruses or touch hands coated with these viruses. You are more likely to get acute bronchitis if your bronchial tree is already damaged. People who smoke are more likely to get acute bronchitis and to have it longer. If you stop smoking, you are less likely to get acute bronchitis in the future.