The investigators propose a randomized trial of two novel TB case-finding interventions among household members of patients diagnosed with active TB: holiday-based screening in a rural South African province (Limpopo) and off-peak (weekend/evening) screening in an urban settlement into which many residents of Limpopo migrate for work. The investigators will enroll index cases of TB plus their household contacts in each setting and randomize them to novel versus standard contact investigation. In Specific Aim 1, investigators will use whole genome sequencing of all cases, overlaying transmission trees with data on human movement, to evaluate associations between mobility and TB transmission in this population. In Specific Aim 2, investigators will employ a multidisciplinary approach to compare novel versus standard contact investigation in each setting along the following dimensions: (a) effectiveness (number of secondary TB cases diagnosed and starting treatment); (b) implementation (reach, fidelity, and maintenance of contact investigation outside of business hours); (c) cost-effectiveness (cost per disability-adjusted life year) and budget impact; and (d) projected population-level impact on TB incidence. Successful completion of these aims will have long-term impact by characterizing the role of mobility in fueling TB epidemics and testing two tailored approaches to improve TB control in highly mobile populations - an underserved group that is increasingly recognized as playing a major role in global TB transmission.
The purpose of this study is to characterize the role of human mobility in fueling TB epidemics and estimate the potential impact of innovative case finding interventions tailored to mobile populations