Tuberculosis (TB) is an infectious disease usually caused by Mycobacterium tuberculosis (MTB) bacteria.[1] Tuberculosis generally affects the lungs, but can also affect other parts of the body.[1] Most infections show no symptoms, in which case it is known as latent tuberculosis.[1] About 10% of latent infections progress to active disease which, if left untreated, kills about half of those affected.[1] The classic symptoms of active TB are a chronic cough with blood-containing mucus, fever, night sweats, and weight loss.[1] It was historically called consumption due to the weight loss.[8] Infection of other organs can cause a wide range of symptoms.[9] Tuberculosis is spread from one person to the next through the air when people who have active TB in their lungs cough, spit, speak, or sneeze.[1][10] People with latent TB do not spread the disease.[1] 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.[11] Diagnosis of latent TB relies on the tuberculin skin test (TST) or blood tests.[11] Prevention of TB involves screening those at high risk, early detection and treatment of cases, and vaccination with the bacillus Calmette-Guérin (BCG) vaccine.[3][4][5] Those at high risk include household, workplace, and social contacts of people with active TB.[4] 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) and extensively drug-resistant tuberculosis (XDR-TB).[1]