is infection with Mycobacterium tuberculosis, a type
of bacterium. It is estimated that approximately 15 million individuals in
the United States and as many as 30% of the world's population are infected.
Tuberculosis infection typically occurs after repeated or prolonged exposure
to the coughing of an actively infected person. Infection can involve any
organ in the body, but the lungs are the most common site of damage. In active infection, there is damage to organs. In latent infection the person carries the bacteria but does not have
current signs of active infection. Latent TB infection is important to diagnose
and treat because it can become active infection. Multidrug-resistant TB is resistant to (cannot be killed
by) standard antibiotics. This type of TB arises from improper or incomplete
treatment of TB infection or through exposure to a person infected with this
type of bacterium. The June 8, 2005, issue of JAMA is
a theme issue devoted to articles about TB.