Culture in LJ medium( Lowenstein Jenssen)
AFB - Ziehl-Nielson stain
WHO estimates that tuberculosis causes 6% of all deaths worldwide, making it the most common cause of death resulting from a single infectious agent.
poverty, crowding, and chronic debilitating illness like diabetes mellitus, Hodgkin disease, chronic lung disease (particularly silicosis), chronic renal failure, malnutrition, alcoholism, and immunosuppression
HIV pandemic has resulted in surge of TB in recent times in the west
infection vs disease
the only evidence of infectioncan be a fibrocalcific nodule at the site of the infection. Such persons are infected but do not have active disease and so cannot transmit organisms to others
When their defenses are lowered, the infection may reactivate to produce communicable disease.