health

When people with active tuberculosis of the lungs or throat cough or
sneeze, they spread bacteria through the air. Other people who breathe
the same air may become infected with the bacteria, which can lodge in
the lungs and begin to grow. From there, the bacteria can move through
the blood and settle in almost any other part of the body, including the
urinary tract, brain, kidneys, lymph nodes*, bones, joints, peritoneum*,
and heart.
Spending lots of time in close quarters with a person who has untreated
active TB is the most common way to becoming infected. Even with close
contact, however, only one-third of people who are exposed to TB infection
become infected. Within a few weeks of the start of effective treatment,
patients are no longer contagious. TB in parts of the body other than the
lungs and throat usually is not contagious. People who have primary tuberculosis
cannot spread it to others.