High risk of tuberculous infection in North Sulawesi Province of Indonesia.

SETTING

Of all the provinces in Indonesia, the highest tuberculosis (TB) case notification rates are reported from North Sulawesi Province.

OBJECTIVE

To estimate the annual risk of tuberculous infection (ARTI) among schoolchildren in the 6-9 year age group.

METHODS

A cross-sectional survey was carried out in 99 schools selected by a two-stage sampling process. Children attending grades 1-4 in the selected schools were administered intradermally with 2 tuberculin units (TUs) of purified protein derivative RT23 with Tween 80, and the maximum transverse diameter of induration was measured about 72 h later. A total of 6557 children in the 6-9 year age group were satisfactorily test-read, irrespective of their bacille Calmette-Guérin (BCG) vaccination status.

RESULTS

Based on the frequency distribution of reaction sizes obtained among satisfactorily test-read children (without and with BCG scar), the estimated ARTI rates when estimated by different methods (anti-mode, mirror-image and mixture model) varied between 1.9% and 2.5%. BCG-induced tuberculin sensitivity was not found to influence the ARTI estimates, as the differences in estimates between children without and with BCG scar were not statistically significant.

CONCLUSION

TB control efforts should be further intensified to reduce the risk of tuberculous infection.