Skin sensitization to mycobacteria amongst school children prior to a study of BCG vaccination in North Lebanon.

1888 school children aged between 7 and 17 years, living in 13 villages in two districts of North Lebanon, were skin tested with four new tuberculins as the initial step in a study of BCG vaccination. The great majority of children were tested with Tuberculin, Leprosin A, Vaccin and Scrofulin. In comparison with other countries where similar studies have been carried out, extremely low levels of sensitization were discovered, indicating very little contact with mycobacteria. There was, however, a statistically significant increase in positivity with increasing age. The results obtained for the villages of each district were significantly different from each other, positivity being greatest in Akkar district for each reagent. The eight villages of Zgharta district could be separated into a lowland group of four villages, a mountain group of three villages and one anomalous mountain village. There was significantly more positivity in the lowland than in the mountain villages. In Akkar district, where leprosy has a low prevalence, positivity to Leprosin A was 8% amongst the children (leaving out an anomalous village). In Zgharta district where the disease does not occur, positivity was 3.4% to Leprosin A for the lowland villages and 0.9% for the group of 3 mountain villages. The two anomalous villages were the only ones in which tuberculosis cases were known to have occurred recently, and they were the only two villages in which Tuberculin positivity exceeded 10%.