Tuberculosis

Tuberculosis (abbreviated as TB for tubercle bacillus) is a common and deadly infectious disease caused by mycobacteria, mainly Mycobacterium tuberculosis. Tuberculosis most commonly attacks the lungs (as pulmonary TB) but can also affect the central nervous system, the lymphatic system, the circulatory system, the genitourinary system, bones, joints and even the skin. Other mycobacteria such as Mycobacterium bovis, Mycobacterium africanum, Mycobacterium canetti, and Mycobacterium microti can also cause tuberculosis, but these species do not usually infect healthy adults.

Over one-third of the world's population now carries the TB bacterium, and new infections occur at a rate of one per second. Not everyone infected develops the full-blown disease, so asymptomatic, latent TB infection is most common. However, one in ten latent infections will progress to active TB disease, which, if left untreated, kills more than half of its victims.

In 2004, mortality and morbidity statistics included 14.6 million chronic active TB cases, 8.9 million new cases, and 1.7 million deaths, mostly in developing countries. In addition, a rising number of people in the developed world are contracting tuberculosis because their immune systems are compromised by immunosuppressive drugs, substance abuse or HIV/AIDS.

The rise in HIV infections and the neglect of TB control programs have enabled a resurgence of tuberculosis.citation needed] Drug-resistant strains have emerged and are spreading; data show that, from 2000 to 2004, 20% of TB cases were resistant to standard treatments and 2% were also resistant to second-line drugs. TB incidence varies widely, even in neighboring countries, apparently because of differences in health care systems. The World Health Organization declared TB a global health emergency in 1993, and the Stop TB Partnership, a coalition of some 500 entities founded in 2000, has developed a Global Plan to Stop Tuberculosis aiming to save 14 million lives between 2006 and 2015.