Tuberculosis

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Tuberculosis (TB) is an infection caused by a germ called the tubercle bacillus or Mycobacterium tuberculosis. Until effective anti-tuberculosis drugs were introduced about 50 years ago, TB was one of the main causes of death.

TB is still a major problem in many countries. It has been on the increase in the developed world in recent years, probably because of increased air travel and movement of people from areas where it is common.

It can affect the lungs (pulmonary TB) or other parts of the body, such as the lymph nodes (tuberculous adenitis or scrofula), the skin and the bones. Tubercle bacilli can remain dormant for years before producing active disease.

In most cases lung infection is well controlled by the immune system, and shows no symptoms. Active lung disease occurs if the immune system becomes less effective.

A person may have had an infection with tuberculosis without being aware. This can be discovered by a tuberculin skin test, the Heaf (or Mantoux) test. When positive, it indicates that the person has a degree of natural immunity. People who test negative do not have this immunity and are more susceptible to infection by TB.

Tuberculin-negative people may benefit from BCG innoculation. This uses a vaccine made from a modified version of the TB germ. It reduces the risk of developing TB in about 70% of those vaccinated for approximately 15 years.