Differential tuberculin testing in Lagos.

School children in lagos were tested with PPD-S and one of the following tuberculins simultaneously namely PPD-G, PPD-A, PPD-Y, PPD-F, and PPD-PL. The tuberculins were prepared from Mycobacterium tuberculosis, the Gause organism, M. avium, M. Kansasii, M. fortuitum and M. marinum respectively. It was found that for the different antigens, among those children who had indurations from 0 to 4 mm those small sized reactions wer generally due to sensitization by opportunist mycobacteria. In contrast to this, among those who had indurations over 10 mm, the reactions were due to sensitization by the human tubercle bacillus. Testing of patients with bacteriologically and radiologically proved tuberculosis showed that practically all of them reacted in an expected manner, i.e. PPD-S elicited larger reactions than PPD-Y, PPD-A, PPD-G, PPD-LL and PPD-F.