Tuberculosis is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacteria tuberculosis. One third of the world’s population is thought to have been infected with M. tuberculosis with new infections occurring at a rate of about one per second. In 2007, there were an estimated 13.7 million chronic active cases globally, while in 2010, there were an estimated 8.8 million new cases and 1.5 million associated deaths, mostly occurring in developing countries. The distribution of tuberculosis is not uniform across the globe; about 80% of the population in many Asian and African countries test positive in tuberculin tests, while only 5–10% of the United States population tests positive. The main symptoms of variants and stages of tuberculosis are given, with many symptoms overlapping with other variants, while others are more (but not entirely) specific for certain variants. Multiple variants may be present simultaneously. About 5–10% of those without HIV, infected with tuberculosis, develop active disease during their lifetimes. In contrast, 30% of those coinfected with HIV develop active disease. Tuberculosis may infect any part of the body, but most commonly occurs in the lungs (known as pulmonary tuberculosis). Who can develop Tuberculosis disease? Persons most likely to develop TB disease are those who have recently become infected with TB through someone with whom they live or have close contact. TB disease usually develops within the first two years after getting infected with TB. After the two years is over, the risk of developing TB disease decreases. However, it may still be possible to develop TB disease if the immune system is weakened by another medical condition, drug abuse, malnutrition or old age. Persons with TB disease who have taken the correct TB medications for a specified period of time do not continue spreading TB to others. TB bacteria do not spread...
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