A prospective study of BCG given to young children in Agra, India--a region of high contact with environmental mycobacteria.

A multiple skin test survey of school children (aged 5-15 years) living in Agra, India showed very high levels of sensitisation to numerous species of mycobacteria and little difference in tuberculin positivity between those with and without BCG scars. A total of 136 children aged 3 months to 8 years, living in Agra, were skin tested with Tuberculin and Leprosin A and examined for scars of previous BCG vaccination. Of those who had not previously received BCG and who had responses to Tuberculin of zero or less than 5 mm induration, 109 were offered BCG vaccination: 107 accepted and as many of them as possible were followed up with repeat skin testing 1 and 2 years later. The results are discussed in relation to the background of environmental sensitisation. A comparison is made with the data obtained from other places, particularly the Lebanon, where there is little sensitisation from the environment. Although the high level of Tuberculin conversion achieved after BCG suggested that the vaccine might have an important protective effect, the large size of Tuberculin responses in comparison with those obtained in the UK was worrying. Evidence was obtained suggesting that sensitisation to mycobacteria may occur in very young children which is not detected by the Tuberculin test, but which influences responses to BCG vaccination.