Similar to the common cold, Tuberculosis (TB) is spreads through the air. When people are sick with pulmonary TB, they can infect other people through coughing, sneezing, talking or spitting. The respective germs are called bacilli.
 

A healthy person needs only to inhale a small number of these germs to become infected. Left untreated, each person with active TB will infect on average between 10 and 15 people per year. However, people infected with TB will not necessarily contract the disease. The immune system 'walls off' the TB bacilli which, protected by a thick waxy coat, can lie dormant for years. When the body’s immune system becomes weakened, the risk of contracting the disease is increased.
 

• Nearly 1% of the world's population is newly infected with TB each year.
• One third of the world's population is currently infected with the TB bacillus. 
• According to the World Health Organization, two million people die each year from this disease.
   

The most common anti-TB drugs are isoniazid, rifampicin, pyrazinamide, streptomycin and ethambutol. Unfortunately, single drug treatment bacilli strains have already been documented in every country surveyed. More recently, major anti-TB drug resistant have emerged as well. A particularly dangerous form of drug-resistant TB is multidrug-resistant TB (MDR-TB), which is defined as TB bacilli resistant to at least isoniazid and rifampicin, which are seen as the two most powerful anti-TB drugs.