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( Bacillus Calmette-Guérin)
Bacille Calmette-Guérin (BCG) is a vaccine against tuberculosis that is prepared from a strain of the attenuated (weakened) live bovine tuberculosis bacillus, Mycobacterium bovis, that has lost its virulence in humans by being specially cultured in an artificial medium for years. The bacilli have retained enough strong antigenicity to become a somewhat effective vaccine for the prevention of human tuberculosis. At best, the BCG vaccine is 80% effective in preventing tuberculosis for a duration of 15 years, however, its protective effect appears to vary according to geography. The history of BCG is tied to that of smallpox. Jean Antoine Villemin first recognised bovine tuberculosis in 1854 and transmitted it, and Robert Koch first distinguished Mycobacterium bovis from Mycobacterium tuberculosis. After the success of vaccination in preventing small pox, scientists thought to find a corollary in tuberculosis. A parallel was drawn between bovine tuberculosis and cow pox, and it was hypothesised that infection with bovine tuberculosis might protect against infection with human tuberculosis. In the late 19th century, clinical trials using M. bovis were conducted in Italy with disastrous results, because M. bovis was found to be just as virulent as M. tuberculosis. Public acceptance was slow and one disaster in particular did much to harm public acceptance of the vaccine. In Lubeck, 240 infants were vaccinated in the first 10 days of life; almost all developed tuberculosis and 72 infants died. It was subsequently discovered that the BCG administered had been contaminated with a virulent strain that was being stored in the same incubator, and led to legal action being taken against the manufacturers of BCG.[2] In 1928 it was adopted by the Health Committee of the League of Nations. However, because of opponents of vaccination, it was not widely used until after World War II. From 1945 to 1948 , relief organizations (International Tuberculosis Campaign or Joint Enterprises) vaccinated over 8 million babies in eastern Europe and prevented the predicted increase of TB after a major war.
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