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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.
From September 2005, a new targeted programme of BCG vaccination was introduced. Only those people at high risk of contracting TB will be vaccinated, as opposed to all school children in the UK.
Symptoms of pulmonary TB include fever, fatigue, loss of appetite and weight, night sweats and persistent cough. Phlegm coughed up may be streaked with blood. Tuberculous pleurisy (affecting the membranes around the lungs) leads to an accumulation of fluid in the pleural cavity (the normally very small space between the membranes) and partial collapse of the lung.
Rarely, the TB in the lung erodes an artery, causing dangerous bleeding into the lung. TB may then spread widely throughout the body via the bloodstream (called miliary tuberculosis). Meningitis is another dangerous complication.
Pulmonary tuberculosis is usually caught from someone by coughing and sneezing tubercle bacilli. The TB germ has a thick capsule, and can survive dry and usually hostile conditions (although it is killed by UV light eg sunlight).
In countries where unpasterised milk is drunk TB may be transmitted in infected milk from cows with Bovine Tuberculosis.
An abnormal chest X-ray may be suggestive of tuberculosis but the diagnosis can only be confirmed by identifying the TB germ in specimens taken from the patient such as the sputum (phlegm).
Tuberculosis is treated with antituberculous drugs in combination, for at least 6 months.
Treatment normally consists of a combination of antibiotics. The standard treatment involves Isoniazid and Rifampicin being given for at least six months. In addition, Pyrazinamide and Ethambutol are also given for the first two months of treatment. Rifabutin, Cycloserine, Capreomycin and Streptomycin can also be used in the treatment of TB if drug resistance has been shown to be present
It is vital to complete the course of drugs as directed. If this is not done the bacteria will not be completely eradicated and drug- resistant strains may develop. Drug-resistant strains of the bacteria have become an increasing problem. The last decade has seen the spread of drug-resistant strains of the TB bacteria. Some strains are now resistant to the two leading drugs, Isoniazid and Rifampicin - this is defined as multi-drug resistance (MDR).
The old BCG vaccination programme, which was delivered through schools, was replaced with an improved programme of targeted vaccination for people at highest risk in September 2005.
The new programme identifies and vaccinates babies and older people who are most likely to catch the disease, especially those living in areas with a high rate of TB or whose parents or grandparents were born in a country where there is a high rate of TB.
Parents and health professionals will be able to find information about the changes on the immunisation website (see Selected links) or by calling NHS Direct on 0845 4647.
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