Tuberculosis ,
MTB or
TB (short for
tubercles bacillus) is a common and in some cases deadly
infectious disease caused by various strains of
mycobacteria, usually
Mycobacterium tuberculosis in humans.
[1] Tuberculosis usually attacks the
lungs but can also affect other parts of the body. It is spread through the air when people who have active MTB infection cough, sneeze, or spit.
[2] 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. 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.
One third of the
world's population is thought to be infected with
M. tuberculosis,
[3][4] and new infections occur at a rate of about one per second.
[5] 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.
[5] In 2007 there were an estimated 13.7 million chronic active cases, 9.3 million new cases, and 1.8 million deaths, mostly in
developing countries.
[6] In addition, more people in the
developed world contract tuberculosis because their
immune systems are more likely to be compromised due to higher exposure to
immunosuppressive drugs,
substance abuse, or
AIDS. 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 US population test positive.
[1]
