'Tuberculosis (TB) is an infectious, contagious, airborne disease, referred to as "the Great White Plague" of 19th century Europe. In 1882, the German physician Robert Koch discovered Mycobacterium tuberculosis (MTB), the bacterium that causes most tuberculosis.
The WHO ranks TB as the second leading cause of death from an infectious disease. There were 8.6 million new TB cases in 2012 and 1.3 million TB deaths. 
Also, in 2012, the WHO estimated that 450,000 people (globally) developed MDR-TB (multidrug-resistant tuberculosis). About 9.6% of these cases were XDR-TB (extensively drug-resistant TB).'