Tuberculosis or TB (short for tubercles bacillus) is a common and often deadly infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis in humans. Tuberculosis usually attacks the lungs but can also affect other parts of the body.

Atelectasis is defined as the lack of gas exchange within alveoli, due to alveolar collapse or fluid consolidation. It may affect part or all of one lung. It is a condition where the alveoli are deflated, as distinct from pulmonary consolidation.