TB is an infectious disease caused by the bacillus Mycobacterium tuberculosis. It particularly affects the lungs (pulmonary TB) but can affect other sites as well (extra pulmonary TB). The disease is spread in the air when people who are sick with pulmonary TB expel bacteria, for example by coughing. Overall, a relatively small proportion of people infected with M. tuberculosis will develop TB disease. TB is also more common among men than women, and affects mainly adults in the most economically productive age groups.

The most common method for diagnosing TB nationwide is sputum smear microscopy, in which bacteria are observed in sputum samples examined under a microscope. Following recent advances in TB diagnostics, the use of rapid molecular tests offered from 32 centres to diagnose TB and drug-resistant TB is increasing in Nepal. Likewise, 2 national reference laboratories are also offering sputum culture facilities in the country.

The currently recommended treatment for new cases of drug-susceptible TB is a six-month regimen (fixed dose combination) of four first-line drugs: isoniazid, rifampicin, Ethambutol and pyrazinamide. Cured Rates was 88% and Treatment Success Rates was 91% for new cases reported in 2014/15. Treatment for multidrug-resistant TB (MDR-TB), defined as resistance to isoniazid and rifampicin (the two most powerful anti-TB drugs) is longer, and requires more expensive and more toxic drugs. For most patients with MDR-TB, the current regimens recommended by WHO last 20-24 months, and treatment success rate was 73%.