A quantitative and qualitative study to investigate the epidemiology of tuberculosis and its determinants in Khomas region, Namibia

Abstract

Namibia has the seventh highest Tuberculosis (TB) incidence rate in the world, but the disease epidemiology is not well researched. This thesis investigated the TB burden and its determinants in the country’s most populous region Khomas, and empirical work was divided into four inter-related phases. Phase one involved a Joinpoint regression analysis of trends in TB notification rates. The results showed that from 1997 to 2015, the notification rates for all forms of TB declined from 808 to 400 per 100 000 population, representing an average annual percent change of -3.9% (95% CI: -6.4 to -1.3%). Significant annual percent changes were observed for all specific types of TB. Phase two focused on the spatial and spatiotemporal analysis of TB notifications from 2006 to 2015, using the Moran’s I and scan statistics. The results showed that TB depicted a strong spatial autocorrelation, with a significant positive Global Moran’s I obtained each year. The northern townships were repeatedly identified as TB hotspots, and these townships mostly had notification rates higher than the city average. Phase three involved a comparative and descriptive cross-sectional survey with 800 participants from two townships. The results showed that participants who were unemployed, consumed alcohol frequently, stayed in overcrowded households, rarely visited healthcare services and had poor TB knowledge were significantly more likely to reside in the high TB burden township. Phase four comprised of a thematic analysis of 14 qualitative interviews exploring TB knowledge, attitudes and practices. The results showed that perceived increased risk of TB infection was attributed to lifestyle behaviours, while the township’s overall disease burden was attributed to poor sanitation, overcrowding and a lack of basic services. In conclusion, despite the overall declining trend, the TB burden in specific townships in Khomas remains worryingly high. Focused prevention interventions are needed to heighten impact in the identified hotspots. Also, further research is needed to study the local burden in relation to internal migration and diabetes, neither of which were measured in this study.