Efficiency of tuberculin as a tool to determine the prevalence of tuberculosis.

: Among 1937 first grade primary school children followed, the results of tuberculin test, the prevalence rate of TB infection was 4.49% with an estimated annual infection rate of 0.75%. Household contacts of tuberculin positive pupils gave a prevalence rate of infection of 30.6%. As for the efficiency of tuberculin screening test, data of this work showed a positive predictive value of 13.3%. Out of 10 diagnosed tuberculous patients, 4 cases were diagnosed for the first time during this study.