Causes of Tuberculosis
TB spreads from person to person via secretions. When someone with TB coughs, sneezes, or talks, tiny droplets of saliva or mucus are expelled into the air, which could be inhaled by another person. Once the inhaled infectious particles reach the alveoli (small sacs in your lungs), another cell called the macrophage engulfs the TB bacteria. The bacteria are transmitted to your lymphatic system and bloodstream and spread to other organs. The bacteria further multiply in organs that have high oxygen pressures, such as the upper lobes of your lungs, your kidneys, bone marrow, and meninges (the membrane that covers your brain and spinal cord).
Fortunately not all those infected contract TB. In most cases the germs are sealed off in the body and they do not multiply. However, if the body's defenses can no longer control the germs, they become active and the person gets TB.
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