BCG vaccine 400 per 100,000 in that higher risk context). The age of the person and the frequency with which BCG is given has always varied from country to country. BCG is prepared from a strain of the attenuated (virulence-reduced) live bovine tuberculosis bacillus, "Mycobacterium bovis", that has lost its ability to cause disease in humans. Because the living bacilli evolve to make the best use of available nutrients, they become less well-adapted to human blood and can no longer induce disease when introduced into a human host. Still, they are similar enough to their wild ancestors to provide some degree of
Inoculation prisoners due to be hanged, an experiment which was witnessed by a number of notable doctors. All survived, and in 1722 the Prince of Wales' daughters received inoculations. The practice of inoculation slowly spread amongst the royal families of Europe, usually followed by more general adoption amongst the people. The practice is documented in America as early as 1721, when Zabdiel Boylston, at the urging of Cotton Mather, successfully inoculated two slaves and his own son. Mather, a prominent Boston minister, had heard a description of the African practice of inoculation from his Sudanese slave, Onesimus, in 1706, and later