Annual risk of tuberculous infection in the western zone of India.
METHODS
Rural and urban areas of six selected districts in the western zone of India.


OBJECTIVE
To estimate the annual risk of tuberculous infection (ARI).


METHODS
A community-based, cross-sectional tuberculin survey was conducted among children aged 1-9 years residing in a sample of rural and urban areas of six districts in the western zone of India. Stratified two-stage cluster sampling was adopted for selection of rural and urban clusters. A total of 48473 children in 600 clusters underwent tuberculin testing with 1TU PPD RT23 with Tween 80; the induration was measured about 72 h after the test.


RESULTS
The BCG scar was observed in 52% of the test-read children. Estimation of the prevalence of infection was based on the frequency distribution of tuberculin reaction size among 22259 children without BCG scar. Reactions > or = 15 mm were considered attributable to infection with tubercle bacilli. The prevalence of infection was estimated to be 9.3%, and the ARI computed from the estimated prevalence was 1.8%. The proportion of infected children was found to be significantly higher in urban than in rural areas.


CONCLUSIONS
The high rate of ARI in the western zone of India calls for further intensification of tuberculosis control efforts.
Chadha
V K
VK
National Tuberculosis Institute, No. 8 Bellary Road, Bangalore, Karnataka, 560 003 India. ntiindia@blr.vsnl.net.in
Vaidyanathan
P S
PS
Jagannatha
P S
PS
Unnikrishnan
K P
KP
Savanur
S J
SJ
Mini
P A
PA
D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007194:India / Q000453:epidemiology; D007223:Infant; D008297:Male; D015995:Prevalence; D018570:Risk Assessment; D012424:Rural Population / Q000706:statistics & numerical data*; D013997:Time Factors; D014374:Tuberculin Test / Q000706:statistics & numerical data; D014376:Tuberculosis / Q000453:epidemiology*; D014505:Urban Population / Q000706:statistics & numerical data*