Latent tuberculosis infection care cascade among the household contacts of pulmonary tuberculosis patients – Findings from an urban feasibility study

Introduction

Latent Tuberculosis infection (LTBI) care cascade involves identification of high-risk individuals, testing, identification of LTBI, initiation of Tuberculosis Preventive therapy (TPT) and documentation of outcomes. There is a dearth of such evidence in Indian setting which needs to be further explored. Hence, this feasibility study with public private engagement was conducted with the primary objective of estimating the prevalence of LTBI among household contacts (HHCs) of pulmonary tuberculosis patients using Interferon gamma release assay (IGRA). Secondary objective was to determine the treatment outcomes among the patients of LTBI initiated on TPT.

Methods

This longitudinal community-based study was conducted in wards 47–51 at urban field practice area of our Tertiary Teaching Institute at Bhopal, Madhya Pradesh. The household contacts of pulmonary tuberculosis patients diagnosed from January–June 2022 and those who satisfied the study criteria were recruited. Those who gave consent for IGRA testing and TPT initiation were followed up for a period of 6 months to assess the treatment outcomes. Data was analyzed using R software.

Results

Of the 64 HHCs screened, 29 were the contacts of microbiologically positive and 35 were the contacts of clinically diagnosed index Tb patients including 4 under five children. Prevalence of LTBI using IGRA was 74.5%. The Contact Investigation Coverage in the urban setting was 77.1% with TPT completion of 72.4% and TPT Coverage of 55.7%. The median time for screening the HHCs since the diagnosis of index case was 14 days while screening to diagnosis was 2.5 days and that of TPT initiation from diagnosis was 22 days.

Conclusion

More than half of those who were tested using IGRA were positive for LTBI. Th public private coordination helped in narrowing the time interval from diagnosis of index tb case to contact tracing and improving the TPT adherence among the HHCs. However, intensive efforts are required to narrow the screening gap of HHCs and TPT initiation. Also, reasons for loss to follow up and missed doses needs to be qualitatively explored.