Gonzalo G. Alvarez, MD, MPH, FRCPC
Pamela Orr, MD, MSc, FRCPC
Wendy L. Wobeser, MD, MSc, FRCPC
Victoria Cook, MD, FRCPC
Richard Long, MD, FRCPC
The Constitution Act of 1982 recognizes three major groups of Aboriginal people in Canada: First Nations (North American Indian), Métis and Inuit (refer to Appendix A, Glossary). Estimates from the 2006 Canadian census (data from the 2011 Census were not available at the time of publication) for the Aboriginal population were as follows: 1,172,790 people identified their ethnic origin as Aboriginal, 698,025 of these as First Nations/North American Indian, 389,780 as Métis and 50,480 as Inuit Footnote 1.Of the total First Nations (FN) population, 564,870 people (81%) are registered according to the terms of the Indian Act of 1876 as Status IndiansFootnote 2. As of December 2011, these individuals are associated with over 600 bands, and 53% of registered FN individuals live on one of more than 1,000 reserves. The First Nations population resides primarily in Ontario and the western provincesFootnote 3. The Inuit span four regions that constitute Inuit Nunangat (Inuit Homeland): Inuvialiut (Northwest Territories), Nunavut, Nunavik (Northern Québec) and Nunatsiavut (Labrador). The Métis are distinct from First Nations, Inuit and non-Aboriginal people and are of mixed Aboriginal and European ancestry. Little is said about the Métis in this chapter because routine surveillance data on Métis status are not systematically collected, and census-based population estimates of Métis are dependent upon self-identification.
Unique challenges exist in the prevention and control of tuberculosis (TB) in First Nations and Inuit populations. These include the wide dispersal of populations over large and remote geographic areas, jurisdictional issues in health care delivery, the imperative to deliver culturally appropriate care, and the prevalence of socioeconomic and biologic risk factors for TB, including poverty, malnutrition, poor housing, diabetes and renal disease.
North and South American human remains dating from the time of pre-European contact show anatomic and radiological evidence of mycobacterial disease, and Mycobacterium tuberculosis complex has been identifiedFootnote 4. However, epidemic TB in Canadian FN and Inuit populations occurred after European contact in the 19th and 20th centuries. Recent work suggests that M. tuberculosis was dispersed across Canada by the fur tradeFootnote 5. This dispersal appears to have been associated with small populations of M. tuberculosis infected individuals existing at a relatively stable level until ecologic, political and economic factors led to expansion in the late 19th and early 20th centuries.
Social and environmental risk factors for the epidemic spread of TB in these populations included the movement of individuals to reserves, hamlets and residential schools. In addition to crowded living conditions, which favoured transmission of infection, malnutrition both on and off reserve fostered progression of infection to disease Footnote 6-10. The story of the TB epidemic in FN and Inuit populations speaks of transgenerational loss and suffering Footnote 6-10. Families and communities were disrupted as children, parents and grandchildren were sent to sanatoria throughout southern Canada for long periods of time, sometimes never to return. Survival was often accompanied by a legacy of emotional, psychological and physical "scars." Those who work in prevention and care in the 21st century must be aware of the existence of a "collective memory" of the suffering associated with the TB epidemic in these populations.
The epidemiology of TB in Aboriginal populations in Canada is described in Chapter 1, Epidemiology of Tuberculosis in Canada. The following points deserve emphasis:
(From Health Canada's Strategy Against Tuberculosis for First Nations On-Reserve) Footnote 16
Provinces and territories have the legislated authority for TB prevention and control within their jurisdictions. In the territories, ultimate responsibility for TB prevention and care for the entire population rests solely with the territorial governments. In contrast, within the provinces, TB prevention and care for FN and Inuit is a shared responsibility that varies by region according to each region's level of collaboration with Health Canada's First Nations and Inuit Health Branch (FNIHB) regional offices, provincial governments and FN or Inuit organizations/communities. These collaborations are influenced by the respective provincial public health legislation. For the Inuit communities within the geographic boundaries of provinces, such as in Nunavik in Northern Québec and Nunatsiavut in Labrador, the provinces are responsible for TB prevention and control. In Nunavik, Québec provides all TB services. In Nunatsiavut, the provincial government of Newfoundland and Labrador offers some services, and FNIHB provides funding to the Nunatsiavut Government to complement the provincial services provided.
Determinants of infection and disease are associated with the agent (M. tuberculosis), the host (affected person) and the environment (social, economic, cultural and political). These factors may affect the risk of infection, disease or both. Determinants may be causally linked (risk factor) with infection and/or disease, or linked through an association (risk marker) that is not necessarily causal. Behaviours such as alcohol and drug abuse may be considered host determinants, but they also relate to the environment as it applies to health.
In Manitoba, central nervous system TB is associated with Aboriginal ethnicity and a particular strain, identified by restriction fragment-length polymorphism, which is prevalent in Aboriginal communities in that provinceFootnote 17. Cytokine assays and studies of in vivo mouse models suggest that this strain is hypervirulent compared with other clinical isolatesFootnote 18. Footnote 19 In Alberta there is no evidence that the Beijing/W family of strains, imported from the Western Pacific, is associated with greater transmission, clustering or penetration into the Aboriginal population of the province Footnote 20.
The following are recognized risk factors for the development of active TB disease in relation to the Canadian Aboriginal population (details regarding the risk factors mentioned below, including the risk of active TB development associated with each, are described in Chapter 6, Treatment of Latent Tuberculosis Infection).
The World Health Organization (WHO) defines social determinants of health as the conditions in which people are born, grow, live, work and age (refer to the Social determinants of health report by the Secretariat). Socioeconomic inequalities, high levels of population mobility and population growth give rise to unequal distribution of social determinants of TBFootnote 44. These factors are seen with higher frequency in the Aboriginal groups in Canada. Some of the key social determinants of health related to TB include 1) food insecurity and malnutrition, 2) poor housing and environmental conditions and 3) financial, geographic and cultural barriers to health care access.
Aboriginal communities are at high risk of living in houses that are overcrowded and in disrepairFootnote 58. Higher TB incidence was shown to be associated with a higher average housing density among First NationsFootnote 59. Furthermore, another study showed an association between the number of people living in a house and self-reported TB in First NationsFootnote 60. In communities with new cases of infectious TB disease, an increased number of individuals will be exposed if there is overcrowding and cramped living conditions, along with poor ventilation in some cases, leading to propagation of infection and disease.
Furthermore, poverty increases the risk of being exposed to many of the biological risk factors such as smoking, alcohol, drug use and malnutrition Footnote 63.
Broadly speaking there are only two ways to eliminate TB: to interrupt transmission altogether and to prevent active TB disease in those with latent TB infection. On the prairies and in the territories, where the incidence of TB in Status Indians is particularly high, three independent lines of evidence point to the importance of ongoing transmission - a high index of transmission, determined by calculating the average number of culture-positive pulmonary cases generated by a single source caseFootnote 12, high rates of disease in children Footnote 65 and a high proportion of clustered M. tuberculosis isolatesFootnote 66 Footnote 67. Preliminary data from the Determinants of TB Transmission Project Footnote 68 (a mixed-method study of TB transmission on the prairies) found that 90% of the Canadian born "potential transmitters" (adult culture-positive pulmonary cases) were of Aboriginal origin Footnote 69.
In many provinces, FN populations are highly mobile in terms of travel between reserves and from reserve to urban areas Footnote 35. This presents challenges to contact investigation and case management, requiring communication and coordination between health jurisdictions. Partnership and collaboration with the community is important for TB prevention and care. Health care workers must be sensitive to the historical and current concerns of their patients. Information sharing and control over health resources are frequent areas of concern for Aboriginal people in the context of the implementation of TB control (and other health care) programsFootnote 70. Lack of knowledge about TB is strongly associated with negative attitudes about, and a worse experience of, the diseaseFootnote 71. A proactive TB health education program that makes use of lay community resources, such as individuals who have recovered from TB, their family members, elders and community health workers, is required in order to achieve a successful prevention and control program in Aboriginal communities. In 2012, Health Canada produced a renewed TB strategy for First Nations On-ReserveFootnote 72, which aims to improve program delivery and performance measurement while establishing standardized, culturally appropriate TB prevention and care services, including community-based initiatives.
Adherence or nonadherence to treatment of latent and active TB is not consistently associated with age, sex or raceFootnote 73. Adherence is a task-specific behaviour, not a personality trait Footnote 74. The terms "adherence" and "nonadherence" may only be used when the patient and provider have agreed to a care plan. Establishing this initial agreement is a critical and often overlooked step.
Various criteria that trigger closer supervision of patients with active TB disease have been suggested in the literature, on the basis of missed appointments or home visits, pill counts in the case of self-administered therapy, urine isoniazid testing or concern voiced by the health workerFootnote 73. Barriers to adherence derive from a complex interaction between the health system, and personal and social factors. Suggested interventions Footnote 75 to remove barriers to adherence at the health system level are as follows:
Cases of nonadherence to TB care frequently highlight potential conflicts between personal and collective rights. In the context of Canadian indigenous communities, an open discussion of these issues is encouraged in order to determine solutions that are culturally and legally sensitive and appropriate Footnote 75.
Successful contact investigation is extremely important in Aboriginal communities, not only because of the burden of active TB disease but also the remote location of many communities, limited access to health care and chronic under-housing, all of which can facilitate transmission Footnote 76. General contact investigation guidelines Footnote 4-6 (also, refer to Chapter 12, Contact Follow-up and Outbreak Management in Tuberculosis Control) may be of limited use as they are not specific to the unique social structure and environment of Aboriginal communities Footnote 77-79. There are other inherent challenges to conducting effective contact investigation in some settings, including language and cultural barriers, as well as the social stigma associated with TB. Inadequate contact investigation leads to missed opportunities to identify secondary active cases and ensure that infected contacts are identified and treated Footnote 80.
Because of the limitations of routine contact investigation and the negative consequences of inadequate contact investigation, new approaches are under investigation and, in some cases, in use to establish effective TB control in those people and communities at greatest risk. A recent publication detailed some of these newer methodologies, including social network analysis (SNA), geographic information systems (GIS) and genomics, in the context of TB contact investigation in low-prevalence countriesFootnote 81. How these approaches could be implemented in Aboriginal communities requires investigation. SNA methods, alone and in combination with conventional and molecular epidemiology, have been used to examine TB clusters and outbreaks both retrospectively and prospectively in both Aboriginal and non-Aboriginal settings Footnote 82-85. Network methods have also clearly documented that locations are key to contact investigation. With respect to Aboriginal TB control, network analysis has helped an understanding of outbreak boundaries, locations of transmission and the risk of TB in contacts in remote communities in ManitobaFootnote 85. GIS techniques are used to visualize data involving distance and locationFootnote 86. These techniques have been used to examine the distribution of TB cases, risk factors for acquiring disease and the relationship of TB to the surrounding environment Footnote 87-89. In a recent outbreak investigation involving TB in Aboriginal people, genomic (bacterial genetics) data from the clustered M. tuberculosis organisms were used to identify transmission events and confirm multiple simultaneous outbreaks within the community Footnote 89. This investigation integrated clinical data, SNA and genomics to better characterize an outbreak that had significantly affected community members. It also confirmed that social factors played a larger role in the outbreak than organism virulence.
According to the most recent statistics released in 2012Footnote 90, the current rate of TB among the Canadian-born Aboriginal population is 26.4 per 100,000. Across Canada rates of new active and retreatment TB cases for the Aboriginal population were as follows: North American Indian 22.2 per 100,000 (188 cases), Inuit 198.6 per 100,000 (116 cases) and Métis 7.5 per 100,000 (26 cases). In 2005, FNIHB set a long-term goal to reduce TB incidence to 3.6 per 100,000 among on-reserve First Nations and Inuit regions in Canada by 2015Footnote 16. Results to date suggest that this goal will not be met (refer to Chapter 1, Epidemiology of Tuberculosis in Canada). To meet these goals and achieve a substantial reduction in rates of TB among Canadian-born Aboriginal peoples it seems likely that intensified and coordinated efforts using novel approaches will be necessary.