The relationship between age and sensitization to PPD-S and atypical mycobacterial antigens among school children in Lagos, Nigeria.

A random sample of school children was tested with PPD-S and one of the following antigens simultaneously namely PPD-F, PPD-G, PPD-PL, and PPD-A. The antigens were prepared from the human tubercle bacillus, Mycobacterium Fortuitum, M. Kansasii the Gause Organism, M. Marinum and M. avium respectively. It was observed that for those who had had no BCG, age had a significant effect on the induration size to PPD-S. The age effect was a linear regression effect, the F for regression being significant at the 1% level. The regression coefficient was found to be 0.4 and the equation to the regression line was Y = -0.6 + 0.4X where X is age and Y is induration size. For all the other antigens, age had no significant effect on the size of induration.