In developed countries, such as the United States, many people think TB is a disease of the past. TB, however, is still a leading killer of young adults worldwide. Some 2 billion people—one-third of the world's population—are thought to be infected with TB bacteria, Mycobacterium tuberculosis (Mtb).
TB is a chronic bacterial infection. It is spread through the air and usually infects the lungs, although other organs and parts of the body can be involved as well. Most people who are infected with Mtb harbor the bacterium without symptoms (have latent TB), but some will develop active TB disease. In 2010, an estimated 8.8 million people fell ill with TB, including 1.1 million cases among people with HIV, according to the World Health Organization.
One in 10 people who are infected with Mtb may develop active TB at some time in their lives. The risk of developing active disease is greatest in the first year after infection, but active disease often does not occur until many years later.
According to the Centers for Disease Control and Prevention (CDC), 11,182 TB cases (a rate of 3.6 cases per 100,000 persons) were reported in the United States in 2010. Both the number of TB cases reported and the case rate decreased, representing a 3.1% and 3.8% decline compared to 2009.
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Last Updated August 13, 2010