What is a contagious bacterial infection that affects the lungs and has inactive active phases?

The correct answer is Tuberculosis

Tuberculosis is a contagious bacterial infection caused by various strains of the bacterium M. tuberculosis. It commonly affects the lungs, which can cause prolonged coughing and other symptoms. The disease can also spread to other parts of the body leading to a wide range of other symptoms.

Tuberculosis is characterized by alternating periods of active and latent infection. During the latent phase, the bacteria lay dormant and do not cause any symptoms. This can last for months or even years. In the active phase the bacteria multiply and cause symptoms.