Tuberculosis

Introduction. 

Tuberculosis is a chronic inflammatory disease whose damage to the body is mainly due to the type-IV hypersensitivity reaction provoked by the presence of Mycobacteria. Mycobacteria have the ability to enter into and survive inside macrophages, eventually causing these to lyse and a new cycle of infection to start. The immune system forms granulomas at the sites of infection, which can be seen in X-rays as distinct dense masses in the lungs.

The Pathogen

Mycobacterium is an acid-fast Gram-positive rod with a high level of mycolic acid in its cell wall, making it resistant to lysosomal degradation. It is an Intracellular pathogen, allowing it to evade the immune system and cause tissue damage.