Return to Pneumonia & Bronchitis

Pneumonia and bronchitis are "lower respiratory diseases" because they affect your lungs or the airways leading into the lungs. "Upper respiratory diseases" affect your nose, throat and sinuses.

Pneumonia

Pneumonia is a serious infection of the lungs. The air sacs (alveoli) in the lungs fill with pus or other liquid. This blocks the normal exchange of oxygen in the lungs, so less oxygen gets into the blood. Without oxygen, the cells in your body don't work properly. Without proper treatment, this lack of oxygen, combined with the spread of infection throughout your body, can cause death.

Until 1936 pneumonia was the leading cause of death in the United States. Since then, the use of antibiotic drugs has brought the disease under control but it's still the sixth leading cause of death.

Bronchitis

Bronchitis affects the air passages (bronchi) that carry air to the lungs from the main airway (the trachea). Inflammation from infection or irritation damages the cells that line the airways. These cells normally contain tiny hairs (cilia) that trap and remove foreign particles you breathe in every day. When the cilia stop working, the air passages become clogged with debris. This increases the irritation even more. In response, the airways start to produce a thick substance (mucus), which causes a unique type of cough. As the irritation continues, the airways become more vulnerable to further infection and tissue damage.

Bronchitis may be acute or chronic. Brief bouts of acute bronchitis (lasting about 10 days) often happen following a severe cold or flu. However, bronchitis may also start on its own, withno prior infection. Chronic bronchitis lasts three months or more, and symptoms can return year after year. Chronic bronchitis can be life-threatening. The condition may come from a series of acute bronchitis attacks, or it may develop gradually because of heavy smoking or inhaling polluted air.

Almost all cases of acute bronchitis are caused by viruses. Many cases of chronic bronchitis come from repeated exposure to irritants such as smoke. This means antibiotic therapy won't help. These drugs can only affect bacterial illnesses and can't fight viral illnesses or irritants. Also, a type of asthma, which produces little wheezing but a lot of cough, is often misdiagnosed as acute bronchitis.

The best treatments for most cases of bronchitis are to avoid irritants, maintain good nutrition, and be patient. Some cases of viral bronchitis can take eight to 12 weeks to clear up. In longer cases of bronchitis, antibiotics or even asthma inhalers may help. Severe chronic bronchitis may cause the bronchi to dilate. That makes them more susceptible to severe - and sometimes drug-resistant - bacterial infections. Avoiding irritants such as cigarette smoke becomes even more important in these cases.

Causes

A major cause of acute bronchitis is:

• Viruses

Major causes of chronic bronchitis include:

• Tobacco smoke, pollutants, dust



• Bacteria

Major causes of pneumonia include:

• Mycoplasmas: the smallest free-living organisms that cause disease

• Viruses

• Bacteria

Other causes:

• Pneumocystis carinii: a fungus that causes pneumonia in many people with AIDS

• Inhaled food, liquid, gases, dust or fungi

• Spirochete: causes Rocky Mountain spotted fever, Q fever and typhus, which may all affect the lungs

• Tuberculosis pneumonia: a very serious and extremely dangerous disease, if it is not treated early

Related Articles What Factors Can Increase My Risk of Getting Pneumonia or Bronchitis? How Do I Know If I Have Pneumonia or Bronchitis? How Are Pneumonia and Bronchitis Treated?

External Source American Lung Association

This article was reviewed and updated June 2007.