An estimated one third of humanity is infected with tuberculosis (TB). Amongst those carrying the pathogen, around 8 million persons come down with clinical disease every year; and out of these, about 1.6 million die, not counting tuberculosis-related deaths in TB-HIV co-infected individuals. (WHO 2008)
TB is a granulamoutous inflammation caused by the infiltration of Mycobacterium tuberculosis (MTB) - a highly contagious bacterium whose small size allows it to stay suspended in the air for a prolonged period of time. Once the infected droplets have infiltrated the lungs they migrate to the distal bronchioles where they can lay dormant for years. The exact mechanism which allows the infection to progress from being dormant to becoming active is not well characterized. However, the progression to the active disease state is tremendously increased in immunocompromised persons, such as those with HIV infection, chronic alcoholism, advanced age and malnourishment.
Excerpt from: Tackling Tuberculosis