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.

Annual risks of tuberculous infection in East Nusa Tenggara and Central Java Provinces, Indonesia.

SETTING: East Nusa Tenggara (NTT) and Central Java Provinces, Indonesia. OBJECTIVE: To estimate the average annual risk of tuberculous infection (ARTI) among school children aged 6-9 years in each province. METHODS: Children attending Classes 1-4 in 65 schools in NTT and 79 in Central Java, selected by two-stage sampling, were intradermally administered 2 tuberculin units of purified protein derivative RT23 with Tween 80 on the mid-volar aspect of the left forearm. The maximum transverse diameter of induration was measured 72 h later. The analysis was carried out among 5479 satisfactorily test-read children in NTT and 6943 in Central Java. One hundred and fifty-five new sputum smear-positive pulmonary tuberculosis (PTB) cases (78 in NTT and 77 in Central Java) were also tuberculin tested. Based on the frequency distribution of reaction sizes among the children and PTB cases, the prevalence of infection was estimated by the mirror-image method using the modes of tuberculous reactions at 15 and 17 mm. RESULTS: Using the 15 mm mode, ARTI was estimated at 1% in NTT and 0.9% in Central Java. Using the 17 mm mode, ARTI was estimated at 0.5% in NTT and 0.4% in Central Java. CONCLUSION: Transmission of tuberculous infection may be further reduced by intensification of tuberculosis control efforts.

Annual risk of tuberculosis infection in West Sumatra Province, Indonesia.

OBJECTIVE: To estimate the annual risk of tuberculosis infection (ARTI) among children attending elementary school Classes I-III in West Sumatra Province, Indonesia. METHODS: The survey was designed to estimate ARTI among children, irrespective of BCG scar status. Fieldwork was carried out in 72 schools selected by two-stage sampling. Children were administered 2 TU of purified protein derivative RT23 with Tween 80 intradermally on the mid-anterior aspect of the left forearm. The maximum transverse diameter of induration was measured at about 72 h. Analysis was carried out among 5653 satisfactorily test-read children aged 6-9 years. RESULTS: The estimation by mirror-image method among all children (without and with BCG scar) revealed an ARTI of between 1% and 1.3%. The estimated ARTIs among children without and with BCG scar varied between 0.8-1.3% and 0.9-1.4%, respectively, using the mirror-image method, anti-mode method and mixture model. CONCLUSION: Tuberculosis control efforts need to be intensified to reduce the risk of transmission of infection.