Tuberculosis, is a common and in many cases lethal infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body. It is spread through the air when people who have an active MTB infection cough, sneeze, or otherwise transmit their saliva through the air. Most infections in humans result in an asymptomatic, latent infection, and about one in ten latent infections eventually progresses to active disease, which, if left untreated, kills more than 50% of its victims.
The classic symptoms are a chronic cough with blood-tinged sputum, fever, night sweats, and weight loss (the last giving rise to the formerly prevalent colloquial term "consumption"). Infection of other organs causes a wide range of symptoms. Diagnosis relies on radiology(commonly chest X-rays), a tuberculin skin test, blood tests, as well as microscopic examination and microbiological culture of bodily fluids.Treatment is difficult and requires long courses of multiple antibiotics. Social contacts are also screened and treated if necessary. Antibiotic resistance is a growing problem in (extensively) multi-drug-resistant tuberculosis. Prevention relies on screening programs and vaccination, usually with Bacillus Calmette-Guérin vaccine.
It was not until 1946, with the development of the antibiotic streptomycin, that effective treatment and cure became possible for Tuberculosis. Prior to the introduction of this drug, the only treatments besides sanatoria were surgical interventions, including bronchoscopy and suction as well as the pneumothorax orplombage technique—collapsing an infected lung to "rest" it and allow lesions to heal—a technique that was of little benefit and was mostly discontinued by the 1950s.
Hopes that the disease could be completely eliminated have been dashed since the rise of drug-resistant strains in the 1980s.
The resurgence of tuberculosis resulted in the declaration of a global health emergency by the World Health Organization (WHO) in 1993.Every year, nearly half a million new cases of multi-drug-resistant tuberculosis (MDR-TB) are estimated to occur worldwide.One third of the world's population is thought to be infected with M. tuberculosis and new infections occur at a rate of about one per second. The proportion of people who become sick with tuberculosis each year is stable or falling worldwide but, because of population growth, the absolute number of new cases is still increasing