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Tuberculosis (TB) Overview

Tuberculosis (TB) describes an infectious disease that has plagued humans since the Neolithic times. Two organisms cause tuberculosis -- Mycobacterium tuberculosis and Mycobacterium bovis.

Physicians in ancient Greece called this illness "phthisis" to reflect its wasting character. During the 17th and 18th centuries, TB caused up to 25% of all deaths in Europe. In more recent times, tuberculosis has been called "consumption."

  • Robert Koch isolated the tubercle bacillus in 1882 and established TB as an infectious disease.
    • In the 19th century, patients were isolated in sanatoria and given treatments such as injecting air into the chest cavity. Attempts were made to decrease lung size by surgery called thoracoplasty.
    • During the first half of the 20th century, no effective treatment was available.
    • Streptomycin, the first antibiotic to fight TB, was introduced in 1946, and isoniazid (Laniazid, Nydrazid), originally an antidepressant medication, became available in 1952.
  • M. tuberculosis is a rod-shaped, slow-growing bacterium.
    • M. tuberculosis' cell wall has high acid content, which makes it hydrophobic, resistant to oral fluids.
    • The cell wall of Mycobacteria absorbs a certain dye used in the preparation of slides for examination under the microscope and maintains this red color despite attempts at decolorization, hence the name acid-fast bacilli.
  • M. tuberculosis continues to kill millions of people yearly worldwide.
    • Most TB cases occur in developing nations that have poor hygiene, limited health-care resources, and high numbers of people infected with HIV.
  • In the United States, the incidence of TB began to decline around 1900 because of improved living conditions.
    • TB cases have increased since 1985, most likely due to the increase in HIV infection.
  • Tuberculosis continues to be a major health problem worldwide. In 2008, the World Health Organization (WHO) estimated that one-third of the global population was infected with TB bacteria.
  • With the spread of AIDS, tuberculosis continues to lay waste to large populations. The emergence of drug-resistant organisms threatens to make this disease once again incurable.
  • In 1993, the WHO declared tuberculosis a global emergency.
Medically Reviewed by a Doctor on 11/20/2017

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Tuberculosis (TB) Tests

Chest X-Ray

Doctors generally order chest X-ray tests in conjunction with taking a medical history and performing a physical exam to confirm or exclude a suspected chest. Some of the common reasons to order a chest X-ray test are listed below:

  • Cough
  • Shortness of breath
  • Chest pain
  • Poor oxygenation (hypoxia)
  • Back pain
  • Chest injury
  • Fever

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