CFAR Awards

David Dowdy, MD, PhD

Epidemiology, Johns Hopkins Bloomberg School of Public Health

Efficiency and Yield of Contact Investigations for TB in Heterogeneous, HIV-Driven Epidemics

David Dowdy, MD, PhD - Image

Epidemics of HIV and tuberculosis (TB) are geographically heterogeneous. We have demonstrated that approaches to case-finding that target geographic “hotspots” (distinct localities where TB incidence is substantially higher than surrounding areas) may have disproportionate impact on TB transmission.  The degree to which such approaches improve the yield (number of cases detected) and cost-effectiveness (cost per case detected) of TB case-finding remains uncertain.
We propose to perform household-based contact investigations for 250 consecutive cases of pulmonary TB in a South African clinic, located in a district (Ekurhuleni) with the lowest TB incidence rate (300 per 100,000/year) in this extremely high burden country.  Assuming that each case has four household contacts, we will have a sample size of 1,000 contacts for this study.  We will measure the number of culture-confirmed  TB cases detected through this program, as well as the total cost (using a micro-costing or “ingredients” approach).  We will then compare these data with data collected previously in a clinic located in a high-incidence “hotspot” (Klerksdorp) (incidence 950 per 100,000/year), collecting similar cost data in that clinic to facilitate direct comparison.  We will link outcomes to a transmission model to project the population-level impact of targeted versus untargeted contact investigation on TB incidence and mortality
We will use these findings as preliminary data for an R01 grant submission that aims to evaluate the relative yield, cost-effectiveness, and population-level impact of targeted versus untargeted TB case finding in HIV-driven epidemics and will publish our results in the scientific literature.