How Pulmonary TB Develops

Pulmonary - Introduction - Infection - Dormant - Active

Early infection of tuberculosis occurs when the causative bacteria enter the body (usually at the lungs) and settle in a clump on the host tissue. Here the bacteria multiply for several weeks until they become so numerous that the body’s immune system recognizes their invasion and an immune response begins. This response in human beings is called a "cell mediated" response and the cells of the lung itself begin to multiply to form a wall around the invading bacteria. The shape of the sore at this point of infection is like a small, swollen tube on the surface of the tissue, and it is called a "tubercle"--which lead to the name of the disease tuberculosis. At this stage of infection, the tubercle is most commonly sealed off and transformed into scar tissue, in which the bacteria become dormant and no longer affect the body.