Tuberculosis in the Qu’Appelle Agency: 1885-1926

Abstract

Introduction: Tuberculosis (TB) is an infectious disease that causes significant morbidity and mortality. Despite the fact that the total burden of TB has decreased dramatically, the distribution of that burden across the Canadian population has not changed. A century ago, the Indigenous population of Canada had a significantly higher TB mortality than the non-Indigenous population. This gap still exists today. TB is a disease of poverty, and understanding the role of the social determinants of health (SDH) may provide insights into the causes of persistence of TB in the Indigenous population. Research questions: This thesis tackles three questions: 1) Can a TB outbreak that took place over a century ago be reconstructed? 2) What can we learn about the relationship between the disease, the population it afflicted, and the environment in which the outbreak took place? 3) How can reconstruction of a TB outbreak be used to evaluate policy interventions? Area studied: Analyses were limited to the Qu’Appelle Agency, located in Southeastern Saskatchewan. Methodology: An agent-based model of socioeconomic environment of the Qu’Appelle Agency was developed to study the relationship between TB and SDH. Data on TB mortality, demographics, agricultural production, material circumstances, and economic factors of production were used to study the relationship between TB and SDH at the aggregate level. Results: 1) Extensive aggregate data analyses were carried out and an agent-based model of TB transmission and of the socioeconomic environment of the Qu’Appelle Agency was developed. 2) Results of these analyses identify a number of important parameters responsible for the high TB mortality in the Agency. These parameters include biological factors, housing, social characteristics, agricultural output, and policies of the Department of Indian Affairs. Conclusions: This research demonstrates that reconstruction of an outbreak of an infectious disease that took place over a century ago is a complex undertaking that hinges on availability of data and significant expertise in a variety of fields, such as health sciences, economics, mathematics, and modelling approaches. The further one goes into the past, the more one is forced to rely on assumptions, which make the reconstructed web of relationships between agent, host, and environment that caused the outbreak less certain. Despite the inherent uncertainty, the process of outbreak reconstruction provides a deep and multi-faceted understanding of the interactions among the agent, the host, and the environment. The resulting model is a useful way of studying policy interventions that could be applied in other contexts as well – to other infectious diseases or TB outbreaks on other reserves. Keywords: [population health, epidemiology, tuberculosis, Indigenous peoples, agent-based modelling, social determinants of health]