Tuberculosis (MTB, TB) is an infectious disease usually caused by the bacterium Mycobacterium tuberculosis.[1] Tuberculosis generally affects the lungs, but can also affect other parts of the body. Most infections do not have symptoms, known as latent tuberculosis. About 10% of latent infections eventually progresses to active disease which, if left untreated, kills about half of those infected. The classic symptoms of active TB are a chronic cough with blood-tinged sputum, fever, night sweats, and weight loss.[1] This weight loss was what gave rise to the old term "consumption" for the disease.[2] Infection of other organs can cause a wide range of symptoms.[3]
Tuberculosis is spread through the air when people who have active TB in their lungs cough, spit, speak, or sneeze.[1][4] People with latent TB do not spread the disease. Active infection occurs more often in people with HIV/AIDS and in those who smoke.[1] Diagnosis of active TB is based on chest X-rays, as well as microscopic examination and culture of body fluids. Diagnosis of latent TB relies on the tuberculin skin test (TST) or blood tests.[5]
Prevention of TB involves screening those at high risk, early detection and treatment of cases, and vaccination with the bacillus Calmette-Guérin vaccine.[6][7][8] Those at high risk include household, workplace, and social contacts of people with active TB.[8] Treatment requires the use of multiple antibiotics over a long period of time.[1] Antibiotic resistance is a growing problem with increasing rates of multiple drug-resistant tuberculosis (MDR-TB).[1]
One-third of the world's population is thought to be infected with TB.[1] New infections occur in about 1% of the population each year.[9] In 2014, there were 9.6 million cases of active TB which resulted in 1.5 million deaths. More than 95% of deaths occurred in developing countries. The number of new cases each year has decreased since 2000.[1] About 80% of people in many Asian and African countries test positive while 5–10% of people in the United States population tests positive by the tuberculin test.[10] Tuberculosis has been present in humans since ancient times.[11]
Tuberculosis is spread through the air when people who have active TB in their lungs cough, spit, speak, or sneeze.[1][4] People with latent TB do not spread the disease. Active infection occurs more often in people with HIV/AIDS and in those who smoke.[1] Diagnosis of active TB is based on chest X-rays, as well as microscopic examination and culture of body fluids. Diagnosis of latent TB relies on the tuberculin skin test (TST) or blood tests.[5]
Prevention of TB involves screening those at high risk, early detection and treatment of cases, and vaccination with the bacillus Calmette-Guérin vaccine.[6][7][8] Those at high risk include household, workplace, and social contacts of people with active TB.[8] Treatment requires the use of multiple antibiotics over a long period of time.[1] Antibiotic resistance is a growing problem with increasing rates of multiple drug-resistant tuberculosis (MDR-TB).[1]
One-third of the world's population is thought to be infected with TB.[1] New infections occur in about 1% of the population each year.[9] In 2014, there were 9.6 million cases of active TB which resulted in 1.5 million deaths. More than 95% of deaths occurred in developing countries. The number of new cases each year has decreased since 2000.[1] About 80% of people in many Asian and African countries test positive while 5–10% of people in the United States population tests positive by the tuberculin test.[10] Tuberculosis has been present in humans since ancient times.[11]
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