Chronic bronchitis is an inflammation of the airways, called the bronchi, resulting in excess mucus production. Although infections often result from this form of Chronic Obstructive Pulmonary Disease (COPD), they are not typically the cause. An infection may produce acute bronchitis, a similar condition that can last days or weeks, but chronic bronchitis is persistent, lasting months or as is often the case, indefinitely.

Asthma is a lung disease that creates inflamed, constricted bronchi (the major airways leading to each lung). The constriction results from contraction of the smooth muscles surrounding the airways. The inflammation stimulates excess mucus production. Because of these and other symptoms, asthma often resembles chronic bronchitis, a form of chronic obstructive pulmonary disease or COPD. However, there are differences.

Unlike asthma or Chronic Obstructive Pulmonary Disease (COPD), tuberculosis has a known cause. It results from infection by a bacterium known as Mycobacterium tuberculosis. While secondary infections are more likely when a person has COPD, due to the tendency to retain excess mucus, the bacterial infection itself is the primary cause of TB.