First tuberculosis prevalence survey in KwaZulu.
The results of a prevalence survey undertaken during 1974 are presented. A stratified 3-stage sampling technique was used to select 3 789 people from 10 randomly chosen sites in KwaZulu. One Heaf test and 2 Mantoux tests were performed on each of 1 769 children under 18 years of age, of whom 28,7% were found to have BCG scars. Of the radiographs taken of persons 15 years of age and older, 893 were found to be negative, 25 (2,7%) disclosed active tuberculosis (TB) and 3 (0,3%) miliary TB. Of the 1 136 sputum specimens collected and examined by fluorescence microscopy, 15 (1,3%) were found to be positive and 9 of them were confirmed by culture. Culture of 1 149 specimens yielded 9 (0,8%) isolations of Mycobacterium tuberculosis and 17 strains of other mycobacteria. The annual rate of infection was calculated at 1,4% by applying Styblo's epidemiological model, and a downward trend was indicated. A follow-up survey after 5 years is needed to confirm this trend.