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

Abstract

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.

The yield of tuberculosis contact investigation on relapsed TB patients and analysis of associated risk factors: Singapore’s experience

“…Index with both culture-positive and smear-positive was also identified as a risk factor for TBI among contacts in our study. Previous studies have also shown that smear positivity of the index case was a risk factor for TBI [ 15 , 16 ]. Our study also shows IGRA conversion and TB disease were more common among those who were culture-positive compared to those who were only PCR-positive, although they did not reach statistical significance.…”

Contact Tracing and Tuberculosis Preventive Therapy for Household Child Contacts of Pulmonary Tuberculosis Patients in the Kyrgyz Republic: How Well Are We Doing?

“…First, the child household contacts were listed only for 1 out of 5 (18%) index TB patients in a country that is home to 30% of the population aged < 15 years [18]. A pilot project from the Kyrgyz Republic on household contact tracing through home visits had reported 111 child household contacts for 67 index TB patients, way higher than 297 listed for 873 index TB patients in the current study [17]. In addition, studies from Armenia (74%), South Africa (46%), Tajikistan (37%), India (30%) and Ethiopia (30%) have reported higher percentages child household contacts amongst index TB patients [21][22][23][24][25].…”

Test and Treat Model for Tuberculosis Preventive Treatment among Household Contacts of Pulmonary Tuberculosis Patients in Selected Districts of Maharashtra: A Mixed-Methods Study on Care Cascade, Timeliness, and Early Implementation Challenges

“…TBI infection was found to be higher among contacts of microbiologically confirmed PTB patients, who have been established to carry a higher risk of transmission [ 15 ]. Previous studies found microbiological confirmation of index patients to be associated with IGRA positivity [ 13 , 16 ]. Therefore, it is crucial to prioritize attention to and focus on HHCs of microbiologically confirmed PTB patients to diagnose and prevent the spread of TBI early.…”