Annual risk of tuberculosis infection in Sri Lanka: a low prevalent country with a high BCG vaccination coverage in the South-East Asia Region.

Introduction: Despite its simplicity, efficiency and reliability, Sri Lanka has not used the Annual Risk of Tuberculosis Infection (ARTI) to assess the prevalence and efficiency of tuberculosis (TB) control. Hence, a national tuberculin survey was conducted to estimate the ARTI. Materials and Methods: A school-based, cross-sectional tuberculin survey of 4352 children aged 10 years irrespective of their BCG vaccination or scar status was conducted. The sample was selected from urban, rural and estate strata using two-stage cluster sampling technique. In the first stage, sectors representing three strata were selected and, in the second stage, participants were selected from 120 clusters. Using the mode of the tuberculin reaction sizes (15 mm) and the mirror-image technique, the prevalence and the ARTI were estimated. Results: The prevalence of TB estimated for urban, rural and estate sectors were 13.9%, 2.2% and 2.3%, respectively. The national estimate of the prevalence of TB was 4.2% (95% CI = 1.7-7.2%). ARTI for the urban, rural and estate sectors were 1.4%, 0.2% and 0.2%, respectively, and the national estimate was 0.4% (95% CI = 0.2-0.7%). The estimated annual burden of newly infected or re-infected TB cases with the potential of developing into the active disease (400/100 000 population) was nearly 10-fold higher than the national new case detection rate (48/100 000 population). Conclusion: The national estimate of ARTI was lower than the estimates for many developing countries. The high-estimated risk for the urban sector reflected the need for intensified, sector-specific focus on TB control activities. This underscores the need to strengthen case detection. Repeat surveys are essential to determine the annual decline rate of infection.

50 Years of Tuberculosis Control in India: Progress, Pitfalls and the Way Forward.

India established the National Tuberculosis Control Project (NTCP) 50 years ago and re-designed it as Revised NTCP (RNTCP) 19 years ago. Tuberculosis (TB) control was beset with obstacles — BCG vaccination was found ineffective in TB control in 1979; human immunodeficiency virus began spreading in India since 1984 with TB as the commonest opportunistic disease; multi-drug resistance was found to be prevalent since 1992. The World Health Organization declared TB as global emergency in 1993. Yet, RNTCP was extended to the whole nation very slowly, taking 13 years from inception. The first objective of RNTCP, namely 85% treatment success has been achieved and case-fatality had dropped by 90%. Still, TB burden continues to remain huge; about half the cases are not getting registered under RNTCP; pediatric TB is neglected; TB drains national economy of US$ 23 billion annually. Therefore, TB control is in urgent need of re-design and re-invigoration, with additional inputs and system re-organization to cover all such gaps. We highlight the need for Public Health infrastructure under which all vertical disease control projects such as RNTCP should be synergized for better efficiency and for establishing Public Health Surveillance for collecting denominator-based data on incidence and prevalence to guide course corrections. India ought to spend 3 to 5 times more on TB control than at present. Control needs clear epidemiologic definition and measurable parameters for monitoring the level of control over time. TB control is both a measure of, and a means to, socioeconomic development.

Prevalence and Annual Risk of Tuberculosis Infection in Rural Mysore.

We carried out a tuberculin survey among 5-10 years old children in rural Mysore (n=1026) to estimate the annual risk of tuberculosis infection (ARTI). 90.8%of them had BCG scar.The prevalence of infection was estimated as 13.3% with 95% CI of 11.4-15.5 and ARTI as 1.38% .These figures are comparatively higher than what is reported from other places in India.

Annual Risk of Tuberculosis Infection Among the Tribal Children of Jhabua, Madhya Pradesh.

A cross sectional tuberculin survey was undertaken to estimate the Annual Risk of Tuberculosis Infection (ARTI) amongst tribal children aged 1-9 years in Jhabua district, Madhya Pradesh, India. Of the 1056 test-read children, 774 (73.3 %) had no BCG scar. The prevalence of infection was estimated as 6.3% (95% CI: 4.8-7.7) and ARTI as 1.2 % (95% CI: 0.9-1.5). The findings suggest that the tuberculosis situation in the tribal population of Jhabua district is not that different from the situation among the non-tribal population in the country. However, there is a need to further intensify tuberculosis control measures in the area.

Annual risk of tuberculous infection in rural areasof Kota district.

Background: A nation wide tuberculin study was undertaken to estimate the Annual Risk of Tuberculous Infection (ARTI) in different parts of India. The study in the rural areas of Kota, one of the districts selected for the survey, is described in this article. Material & Methods: A total of 6264 children 1-9 years of age, residing in 64 clusters were registered into the study. The children were subjected to the standard tuberculin test using 1 TU PPD RT23 with Tween 80 procured from BCG Laboratory, Guindy and the maximum transverse diameter of the induration was measured at about 72 hours. Results: A total of 3157 children without BCG scar and 1520 with BCG scar was successfully test read. The prevalence of infection among children without BCG scar using the mirror image technique was estimated as 13.6% and the ARTI was computed at 2.6%. Using similar technique, the prevalence of infection among the entire study group-irrespective of BCG scar was estimated as 14.9% and the ARTI was computed at 2.8%. Conclusion: The findings indicate a high rate of transmission of tuberculous infection in rural areas of Kota and emphasise the need for further strengthening of tuberculosis control measures.