Estimation of annual risk of tuberculosis infection (ARTI) among children aged 1-9 years in the south zone of India.
OBJECTIVE
To estimate the annual risk of tuberculosis infection (ARTI) among children aged 1-9 years in the south zone of India.


METHODS
The survey was carried out in a representative sample of villages and census enumeration blocks of towns in four south Indian states, as a part of a nationwide tuberculin survey.


METHODS
Six districts were selected through systematic random sampling. Four hundred and twenty rural clusters and 180 urban clusters were selected from these districts on the basis of the rural-urban ratio in the entire zone. To obtain the required sample of 12,000 children without bacille Calmette-Guérin (BCG) vaccination, 51,000 had to be covered. Eighty-five children from each cluster were tuberculin tested and read for reaction sizes. The ARTI was computed from the estimated prevalence of TB infection among children without a BCG scar.


RESULTS
Among 52,951 children registered for the study, 50,846 (96%) had a tuberculin test result. The BCG coverage for the study population was about 65%. Among 17,811 children without a BCG scar, the prevalence of infection was 5.9% (95%CI 4.0-7.7%); the corresponding ARTI was 1.0% (95%CI 0.7-1.4%) [correction].


CONCLUSIONS
The estimated ARTI for the south zone is 1.0%, as compared to the national average of 1.7% used for programme evaluation. This baseline information should be useful for the assessment of future trends.
Kolappan
C
C
Tuberculosis Research Centre, ICMR, Chennai, India.
Gopi
P G
PG
Subramani
R
R
Chadha
V K
VK
Kumar
P
P
Prasad
V Venkatesh
VV
Appegowda
B N
BN
Rao
R S Nagabhushana
RS
Sashidharan
R
R
Ganesan
N
N
Santha
T
T
Narayanan
P R
PR
D001500:BCG Vaccine / Q000008:administration & dosage*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007194:India / Q000453:epidemiology; D007223:Infant; D008297:Male; D012306:Risk; D013223:Statistics as Topic / Q000379:methods; D014376:Tuberculosis / Q000453:epidemiology* / Q000517:prevention & control
D001500:BCG Vaccine