Tuberculosis (TB)

Tuberculosis (TB) is an infectious disease usually caused by Mycobacterium tuberculosis (Mycobacterium tuberculosis) bacteria. TB primarily affects the lungs but can also affect other parts of the body. Most infections show no symptoms, in which case it is known as latent tuberculosis. About 10% of latent infections progress to active disease which, if left untreated, kills about half of those affected. The classic symptoms of active TB are a chronic cough with blood-containing sputum, fever, night sweats, and weight loss. The infection is spread through the air when people who have active TB in their lungs cough, spit, speak, or sneeze.

Causes and Risk Factors

TB is caused by the bacterium Mycobacterium tuberculosis. It is spread through the air from person to person, when people with active TB in their lungs cough, sneeze, or spit. People with latent TB do not spread the disease. Risk factors for TB include HIV/AIDS, smoking, diabetes mellitus, and malnutrition. Being in close contact with people with TB, poor living and working conditions, and traveling or living in certain countries also increase the risk.

Diagnosis

Diagnosing TB involves a skin test called the Mantoux tuberculin skin test, blood tests, chest X-rays, and a microscopic examination and culture of body fluids. The Mantoux test, also known as the tuberculin skin test, involves injecting a small amount of tuberculin into the skin and measuring the body's immune response.

Treatment

The primary treatment for active TB is a course of multiple antibiotics over a long period, typically six months. The most common medications used are isoniazid, rifampicin, ethambutol, and pyrazinamide. Treatment for latent TB, which is not always necessary, is usually with isoniazid or rifampin alone to prevent the development of active disease.

Prevention

Preventive measures for TB include screening those at high risk, early detection and treatment of cases, and vaccination with the BCG vaccine. The BCG vaccine is effective at preventing severe forms of TB in children but its effectiveness in adults is variable and decreases over time.

Epidemiology

Tuberculosis is one of the top 10 causes of death worldwide. In 2019, an estimated 10 million people fell ill with TB, and 1.4 million died from the disease. Over 95% of cases and deaths are in developing countries. The rate of TB varies with age, sex, and geographical region.

History

TB has been present in humans since antiquity. The earliest unambiguous detection of TB dates back to 4000 BC in mummies. The disease was called "consumption" due to the weight loss. Robert Koch discovered the causative agent, Mycobacterium tuberculosis, in 1882, for which he received the Nobel Prize in Physiology or Medicine in 1905.

Society and Culture

Efforts to control TB include health services integration, improving socioeconomic conditions, and research into vaccines and treatments. The World Health Organization (WHO) declared TB a "global health emergency" in 1993 and launched the End TB Strategy in 2015, aiming to reduce TB deaths by 95% and to cut new cases by 90% between 2015 and 2035.