Transmission of TB
Tuberculosis (TB) is a contagious disease. It spreads through the air just like the normal cold. Only people who are sick with TB are infectious. When infectious people cough, sneeze, talk or spit, they expel TB germs, known as bacilli, into the air. It only takes the inhalation of a small number of germs to be infected.
If TB is left untreated, each infected person with the active TB disease will infect between 10 and 15 people every year. But people infected with the TB bacilli will not necessarily become sick with the disease. The immune system "walls off" the TB bacilli which, protected by a thick waxy coat, can lie dormant for years. If the immune system is weak, the chances of becoming sick are greater.
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