Study population

A total of 52,951 children were registered in the rural and urban areas of six selected districts in the zone. Of these, 52,624 were subjected to tuberculin testing. While tests were performed satisfactorily among 52,300 children, these were unsatisfactory among 324 (0.6%) children. Among satisfactorily tested children, 50,533 were test read. Of these 17,811 were without BCG scar, 32,549 with BCG scar and the BCG scar status was doubtful among 173 children (Flow chart).

The proportion of children with BCG scar among satisfactorily test read children was 64.4%. It was about 62.3% in rural and 69.4% in urban areas. This difference was statistically significant. The proportion of children with scar was found to vary between rural and urban areas and also between individual districts (table 7.2.1). It was higher among males compared to females though not statistically significant.

The analysis for estimating prevalence of infection and ARTI was performed among 17811 satisfactorily test read children without BCG scar.

The frequency distribution of tuberculin reaction size

The frequency distribution of tuberculin reaction size among children without BCG scar in the south zone and separately for rural and urban strata are presented at Figures 7.2.1 to 7.2.3. These distributions were observed to be bimodal though the mode of reactions attributable to infection with tubercle bacilli and the anti-mode could not be defined clearly. The cut off point for estimating prevalence of infection with tubercle bacilli was considered at 16 mm for rural areas and at 12 mm for urban areas. The mode was located at 19 mm for rural stratum. For urban stratum, the frequencies at 18, 19 and 20 mm were almost same and the mode was chosen at 19 mm, the mid-point.

Estimated prevalence of infection and ARTI

i) All reactions >16 mm in rural stratum and > 12 mm in urban stratum were considered due to infection with tubercle bacilli (Method I).

ii) By mirror image technique considering the mode at 19 mm (Method II).

The prevalence of infection in the zone was estimated at 6.1% by method I and 5.9% by method II. The ARTI computed was 1.1% by method I and 1.0% by method II. The confidence limits are given in the table 7.2.2.

A significantly higher proportion of children was found to be infected in urban stratum compared to rural stratum, by both Methods. Consequently, the estimated ARTI was higher in urban stratum than in rural. In rural stratum, the estimated ARTI was 0.8% by Method I and 0.8% by Method II. In urban stratum, the estimated ARTI was 1.9% by Method I and 1.6% by Method II. Therefore, the estimates by two methods were almost similar.

The proportion of infected children and the estimated ARTI was found to be higher among females (P<0.05). The ARTI was 1.2 % among females compared to 1.0% among males by Method I. The corresponding ARTI values were 1.1% and 0.9% respectively by Method II.

The estimated ARTI when computed from the estimated prevalence among 5-9 years age group was 1.1% by method I and 1.1% by method II. The corresponding estimates of ARTI among 1-4 year age group were 0.9% and 0.7% Method I & Method II respectively.

The proportion of children found to be infected in the rural and urban areas of the districts is presented in section 7.6.

FlowChart
Study Population - South Zone

Table 7.2.1 : Proportion (%) of children (satisfactorily test read)
with BCG scar by District

Table 7.2.2 : Prevalence of infection among children 1-9 years of age
andcomputedARTI- South zone

Table 7.2.3 : Prevalence of Infection and ARTI by stratum, sex and age group
- South zone

Fig. 7.2.1 : Frequency distribution of tuberculin reaction size among
children 1-9 years of age, without BCG scar - South zone

Fig. 7.2.2 :Frequencydistribution of tuberculin reaction sizeamong
children 1-9 years of age, withoutBCGscar - rural stratum, South zone

Fig. 7.2.3 :Frequencydistribution of tuberculin reaction sizeamong
children 1-9 years of age, withoutBCGscar - urban stratum, South zone

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