<s>[INST] How is TB spread? [/INST] TB is spread from an infectious person who is coughing, to another person through the
air. Like the common cold, TB is spread through aerosolized droplets after infected
people cough, sneeze or even speak. People nearby, if exposed long enough, may
breathe in bacteria in the droplets and become infected. People with TB disease of the
lungs are most likely to spread bacteria to those with whom they spend time every day—
including family members, friends and colleagues.
After a person with a healthy immune system breathes in TB bacteria, he or she will
have 10% lifetime chance of developing TB (compared to a person living with HIV who
has a 10% chance of developing TB each year). If a person's immune system is
compromised or becomes compromised, however, the bacteria will begin to multiply.
From the lungs, bacteria can move through the blood to other parts of the body, such as
the kidney, spine and brain.  Source: UNAIDS. Link: https://data.unaids.org/pub/factsheet/2006/tb_hiv_qa.pdf. Field: Lung Disease. Disease: Tuberculosis </s>