Implementing contact tracing for tuberculosis in Kyrgyz Republic and risk factors for positivity using QuantiFERON-TB Gold plus.

BACKGROUND: Effective active case finding (ACF) activities are essential for early identification of new cases of active tuberculosis (TB) and latent TB infection (LTBI). Accurate diagnostics as well as the ability to identify contacts at high risk of infection are essential for ACF, and have not been systematically reported from Central Asia. The objective was to implement a pilot ACF program to determine the prevalence and risk factors for LTBI and active TB among contacts of individuals with TB in Kyrgyz Republic using Quantiferon-TB Gold plus (QuantiFERON). METHODS: An enhanced ACF project in the Kyrgyz Republic was implemented in which close and household (home) contacts of TB patients from the Issyk-Kul Oblast TB Center were visited at home. QuantiFERON and the tuberculin skin test (TST) alongside clinical and bacteriological examination were used to identify LTBI and active TB cases among contacts. The association for QuantiFERON positivity and risk factors were analysed and compared to TST results. RESULTS: Implementation of ACF with QuantiFERON involved close collaboration with the national sanitary and epidemiological services (SES) and laboratories in the Kyrgyz Republic. From 67 index cases, 296 contacts were enrolled of whom 253 had QuantiFERON or TST results; of those 103 contacts had LTBI (positive TST or IGRA), and four (1.4%) active TB cases were detected. Index case smear microscopy (OR 1.76) and high household density (OR 1.97) were significant risk factors for QuantiFERON positivity for all contacts. When stratified by age, association with smear positivity disappeared for children below 15 years. TST was not associated with any risk factor. CONCLUSIONS: This is the first time that ACF activities have been reported for Central Asia, and provide insight for implementation of effective ACF in the region. These ACF activities using QuantiFERON led to increase in the detection of LTBI and active cases, prior to patients seeking treatment. Household density should be taken into consideration as an important risk factor for the stratification of future ACF activities.

Implementation of whole genome sequencing for tuberculosis diagnostics in a low-middle income, high MDR-TB burden country.

Whole genome sequencing (WGS) is revolutionary for diagnostics of TB and its mutations associated with drug-resistances, but its uptake in low- and middle-income countries is hindered by concerns of implementation feasibility. Here, we provide a proof of concept for its successful implementation in such a setting. WGS was implemented in the Kyrgyz Republic. We estimated needs of up to 55 TB-WGS per week and chose the MiSeq platform (Illumina, USA) because of its capacity of up to 60 TB-WGS per week. The project's timeline was completed in 93-weeks. Costs of large equipment and accompanying costs were 222,065 USD and 8462 USD, respectively. The first 174 WGS costed 277 USD per sequence, but this was skewed by training inefficiencies. Based on real prices and presuming optimal utilization of WGS capacities, WGS costs could drop to 167 and 141 USD per WGS using MiSeq Reagent Kits v2 (500-cycles) and v3 (600-cycles), respectively. Five trainings were required to prepare the staff for autonomous WGS which cost 48,250 USD. External assessment confirmed excellent performance of WGS by the Kyrgyz laboratory in an interlaboratory comparison of 30 M. tuberculosis genomes showing complete agreeance of results.