The only way that tuberculosis can be spread is when one person transmits the bacteria to another person through the air. Shaking hands or sharing dishes will not transmit the bacteria. When a person with tuberculosis coughs, sneezes, speaks, or laughs, tiny microscopic droplets containing the tuberculosis bacteria are sent into the air, causing people nearby to breathe in these bacteria and possibly become infected.
Tuberculosis is spread through the air. People cannot get infected with tuberculosis through handshakes, sitting on toilet seats, or sharing dishes and utensils with someone who has tuberculosis.
When a person with tuberculosis coughs, sneezes, speaks, sings, or laughs, tiny microscopic droplets containing the tuberculosis bacterium (Mycobacterium tuberculosis) are sent into the air. People nearby may breathe in these bacteria and become infected. When a person breathes in tuberculosis bacteria, the bacteria can settle in the lungs and begin to grow. From there, they can move through the blood to other parts of the body, such as the kidneys, spine, and brain.
The bacteria can only be transmitted by people with active tuberculosis (see Latent Versus Active Tuberculosis). Tuberculosis transmission from an infected person is most likely to occur with people whom they spend time with every day. This includes family members, friends, and co-workers. People with tuberculosis who have been treated with the correct drugs for at least two weeks, however, are no longer contagious and do not spread the bacteria to others.
When a person has tuberculosis in the lungs or throat, tuberculosis transmission can occur to other people. People with tuberculosis in other parts of the body, such as the kidneys or spine, usually cannot spread the bacteria to others.