Impact of improved treatment success on the prevalence of TB in a rural community based on active surveillance.

OBJECTIVE: To study the impact of improved treatment outcome of a cohort of patients treated under DOTS strategy on the prevalence of pulmonary tuberculosis (TB) in the community. DESIGN: The data from TB register of one Tuberculosis Unit (TU) in Tiruvallur district of Tamilnadu, and two TB disease surveys conducted in the same area during 1999-2003 were analysed. The successful treatment outcome was compared to the prevalence of TB in the subsequent cohort. RESULTS: The proportion of patients who completed treatment successfully was 75.3% in the first cohort period. This higher proportion of treatment success among patients treated under DOTS in the first cohort period (1999-2001) compared to the 51-55% reported during SCC, resulted in a lower prevalence of smear-positive cases, irrespective of culture results observed in the survey conducted during 2001-2003 compared to that in the survey conducted during 1999-2001 (252 vs. 323 per 100,000; annual decline of 9%). Similarly, a decline in culture-positive cases, irrespective of smear results, was also observed (443 vs. 605; annual decline 11%). CONCLUSION: The higher proportion of successful completion of treatment after DOTS implementation was associated with a substantial decline in the prevalence of TB. These findings showed that we are in the direction towards achieving the Millennium Development Goals (MDGs).