Chapter 1: Canadian Tuberculosis Standards 7th Edition: 2014 – Epidemiology of Tuberculosis in Canada
- Table of Contents
- Chapter 1. Epidemiology of Tuberculosis in Canada
- Chapter 2. Pathogenesis and Transmission of Tuberculosis
- Chapter 3. Diagnosis of Active Tuberculosis and Drug Resistance
- Chapter 4. Diagnosis of Latent Tuberculosis Infection
- Chapter 5. Treatment of Tuberculosis Disease
- Chapter 6. Treatment of Latent Tuberculosis Infection
- Chapter 7. Nonrespiratory Tuberculosis
- Chapter 8. Drug-resistant Tuberculosis
- Chapter 9. Pediatric Tuberculosis
- Chapter 10. Tuberculosis and Human Immunodeficiency Virus
- Chapter 11. Nontuberculous Mycobacteria
- Chapter 12. Contact Follow-up and Outbreak Management in Tuberculosis Control
- Chapter 13. Tuberculosis Surveillance and Screening in Selected High-risk Populations
- Chapter 14. Tuberculosis Prevention and Care in First Nations, Inuit and Métis Peoples
- Chapter 15. Prevention and Control of Tuberculosis Transmission in Health Care and Other Settings
- Chapter 16. Bacille Calmette-Guérin (BCG) Vaccination in Canada
Chapter 1 - Epidemiology of Tuberculosis in Canada
Jessica Halverson, MPH, MSW
Edward Ellis, MD MPH, FRCPC
Victor Gallant, MA
Chris P. Archibald, MDCM, MHSc, FRCPC
Table of Contents
- 1. Key Messages/Points
- 2. Background
- 3. Incidence and Mortality
- 4. Age and Sex Distribution
- 5. Distribution by Population Group and Province/Territory
- 6. Tuberculosis in Canadian-born Aboriginal Peoples
- 7. Tuberculosis in the Foreign-born Population
- 8. Disease Site
- 9. TB-HIV Coinfection
- 10. Drug Resistance
- 11. Treatment and Case Outcomes
- 12. Summary of Salient Trends
- 13. Conclusions
- 14. References
- In Canada, the overall rate and annual number of cases of tuberculosis have continued to decline.
- However, disparities are pronounced in certain population groups and geographic regions; foreign-born individuals and Aboriginal peoples in particular are disproportionately affected by TB.
Global Epidemiology Overview
The World Health Organization (WHO) estimated that there were 8.8 million incident cases of TB worldwide in 2010, for an incidence rate of 128 cases per 100,000 populationFootnote 1. As a result of improvement in general living conditions and overall population healthFootnote 2, coupled with intensive efforts by the global Stop TB Strategy, the number of annual incident cases has been falling since 2006. Similarly, the incidence rate has been decreasing since it peaked at 141 cases per 100,000 population in 2002Footnote 3. In 2010, one-eighth of incident cases were coinfected with HIV, 82% of whom were in the African Region of the WHOFootnote 4. Furthermore, there were an estimated 1.4 million people who died as a result of TB in 2010, 25% of whom were coinfected with HIVFootnote 4. The Stop-TB Partnership target of reducing mortality by 50% from 1990 to 2015 is likely to be met in all WHO regions except the African Region, but mortality rates continue to have a significant impact: nearly 10 million children were orphaned as a result of TB deaths in 2009 alone.
Of the 8.8 million estimated incident cases in 2010, 5.7 million were actually reported, for an estimated case detection rate of 65%Footnote 4. Of cases detected in 2009, the treatment success rate for smear-positive cases was 87%, which is the highest success rate ever reportedFootnote 4. From 1995 through 2010, 46 million individuals were successfully treated, and an estimated 6.8 million deaths were averted in programs that adopted the DOTS (Directly Observed Treatment Short Course)/Stop TB StrategyFootnote 4.
Multidrug-resistant (MDR) TB remains a significant challenge, 150,000 annual deaths being estimated in 2008 and 650,000 prevalent cases in 2010Footnote 4. While it is estimated that 3.4% of new and 20% of retreatment cases starting treatment in 2010 had MDR-TB, only 16% of these cases were treated for the conditionFootnote 1. This can be attributed to the fact that less than 5% of new and previously treated TB patients were tested for MDR-TB in most countriesFootnote 1 Footnote 4.
Surveillance of Active TB in Canada
It is a requirement of local public health authorities to report all cases of TB to their respective provincial/territorial TB program. Provincial and territorial TB programs then voluntarily submit reports of TB cases that meet the case definition for national-level surveillance to the Canadian TB Reporting System (CTBRS). The CTBRS is managed by the Public Health Agency of Canada and maintains selected non-nominal information for each case of active TB, including, but not limited to, demographic, clinical, diagnostic, treatment and outcome details.
The most recent TB reports for Canada are available at: Public Health Agency of Canada, Tuberculosis Prevention and Control website.
The most recent WHO reports on TB are available at: World Health Organisation, Tuberculosis (TB) website.
Incidence and Mortality
In the first half of the 20th century, TB was a major cause of morbidity and mortality in Canada. Historical data on the reported number of cases of TB and the number of deaths attributed to TB are available from 1924. As illustrated in Figure 1, deaths from TB appeared to outnumber new diagnoses each year during the 1920s. This may reflect incomplete reporting of all cases, or it may indicate that reported cases only reflected hospitalized cases, whereas deaths captured all terminal cases of TB whether they were hospitalized or not. Systematic reporting of TB cases was instituted on a national basis in 1933, providing a more accurate and complete record of the burden of TB in Canada through the century.
From the available reports, in 1926, 1 in 13 of all reported deaths in Canada was due to TB, a number slightly higher than the number of deaths reported for cancerFootnote 5. As a result of improved living conditions and isolation of some infectious cases in sanatoria, incidence and mortality rates began to fall in subsequent years, and rates further declined with the introduction of effective antibiotic treatment in the mid-20th century (Figure 1).
Figure 1. Reported tuberculosis incidence and mortality rates in Canada, 1924-2010
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The line graph shows the trends in the incidence rate (solid trend line) and the all-cause mortality rate (dashed trend line) for all TB cases reported in Canada for the years 1924 to 2010. The horizontal axis shows the reporting years from 1924 to 2010 and the vertical axis displays the rate per 100,000 population.
Between 1924 and the 1946 the TB incidence rate increased from 44 per 100, 000 to a high of 103 per 100,000 population. Between 1946 and 1970 the rate of TB in Canada rapidly declined to 21.2 cases per 100,000 population. Since 1970 the decrease in the overall reported incidence rate has been gradual. Between 2000 and 2010 the reported incidence rate has remained stable at approximately 5.0 per 100,000 population.
Between 1924 and the early 1970s the mortality rate from all causes for TB cases declined steadily with a more rapid decline starting in 1950 and carrying through 1965. Since 1975 the mortality rate from all causes has remained stable at 0.4 per 100,000 population.
Over the past two decades, both the number of reported TB cases and the overall Canadian incidence rate have continued to decline, albeit much more gradually than the drop observed between 1950 and 1990. In 1990, the rate was 7.0 per 100,000 population (Figure 2), which fell to an all-time low in 2010 of 4.6 per 100,000 population (1,577 cases reported for 2010).
Figure 2. Reported TB cases and incidence rates in Canada, 1990-2010
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The graph shows the number of reported TB cases (vertical bars) and the reported incidence rate (solid line) in Canada for the years 1990 to 2010. The horizontal axis shows the reporting year. The vertical axis on the left side of the graph shows the number of reported cases and the vertical axis on the right side of the graph shows the reported incidence TB rate per 100,000 population.
Between 1990 and 2010, the number of reported cases has steadily declined from around 2,100 cases to 1,600 cases. Between 2005 and 2010 the annul number of reported cases has remained stable at around 1,600 case. Similarly, the rate has slowly declined over the period from approximately 7.0 per 100, 000 in 1990 to approximately 5.0 per 100 000 for the past six years.
Age and Sex Distribution
The reported TB incidence rate has always been higher among males than females in Canada; however, the differential has decreased over time. In 2010, the male to female ratio was 1:0.8. Between 2000 and 2010, individuals in the 25-34 and 35-44 year age groups accounted for the largest number of cases relative to other age groups. However, the highest age-specific rate was found in the 75+ age group. For 2010, 35% of the cases were between the ages of 25 and 44, whereas the highest age-specific rate, at 9.6 per 100,000, occurred among those aged 75 years or older (Figure 3). Overall, by age and sex, males 75 years of age and over had the highest rate, at 13.6 per 100,000 population.
Figure 3. Reported TB incidence rate by sex and age group in Canada, 2010
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The graph shows the reported TB incidence rate by age group showing the differences between males and female for the year 2010. The horizontal axis shows the age-groups analysed (<1, 1-4, 5-14, 15-24, 25-34, 35-44,45-54, 55-64,65-74 and 75+). The vertical axis shows the incident rate per 100,000 population. Data for females are represented by a solid pink trend line and males by a solid red trend line.
The graph shows very little difference in the incidence rates between male and females for the age groups from < 1 to 25-34. Between <1 and 14 year of age, the rate goes from approximately 3.0 per 100,000 down to less than 1 per 100,000. Between the 5 and 34 years of age, for both males and females, the reported incidence rate slowly increases to approximately 6 cases per 100,000 population. However by 44 years the incidence rate for males starts increasing relative to females and by the 75+ age group the incidence rate for male (13.6 per 100,000 population) is over 2 times the rate reported for females (5.7 per 100,000 population).
Distribution by Population Group and Province/Territory
Although the overall rate in Canada continues to decline, the TB burden is not shared equallyFootnote 6. In particular, Canadian-born Aboriginal peoples and foreign-born individuals are disproportionately affected (Figure 4). From 1970 to 2010, the proportion of active TB cases in the Canadian-born non-Aboriginal population decreased significantly, from 67.8% to 11.8%. During the same period, the proportion among foreign-born individuals increased significantly, from 17.7% to 67.0%, and the proportion among Canadian-born Aboriginal peoples increased from 14.7% to 21.2%.
Figure 4. Percentage of reported TB cases by population group in Canada, 1970-2010
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The graph shows the percentage of reported TB cases by origin group (foreign-born represented by the solid line trend line, Canadian-born non-Aboriginal represented by the dashed trend line and Canadian-born Aboriginal population represented by the dotted trend line) for the years 1970 to 2010. The horizontal axis represents the year cases were reported and the vertical line represents the percent of the total cases reported (0%– 100%).
In 1970 the Canadian-born non-Aboriginal population made up almost 68% of all reported cases in Canada, the foreign born population made up 18% of the cases and the Canadian-born Aboriginal population made up approximately 15% of reported cases. The graph shows that the percentage of cases represented by the Canadian-born non-Aboriginal population steadily decreased and by 2010 they represented 12% of the cases. During the same time the percentage of cases represented by the foreign-born population steadily increased, and by 2012 foreign-born individual made up 67% of all cases. Finally between 1970 and 2010 the percentage of cases represented by Canadian-born Aboriginal remained constant and by 2010 only increased slightly to 21% of all reported cases.
Cases among Canadian-born non-Aboriginal people continue to drop. In 2010, this population group had an incidence rate of 0.7 per 100,000 population (Figure 5).
Figure 5. Reported TB incidence rate by population group in Canada, 2000-2010*
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This graph shows the reported incidence rate of TB cases by origin group (foreign-born represented by the solid line trend line, Canadian-born non-Aboriginal represented by the dashed trend line and Canadian-born Aboriginal population represented by the dotted trend line) The horizontal axis represents the year cases were reported and the vertical line represents the rate per 100,000 population.
Between 2000 to 2010 the Canadian-born Aboriginal population reported the highest incidence rates of all three origin groups ranging from 20 and 30 cases per 100,000 population. The reported TB incidence rate in the foreign-born, between 2000 and 2010 displays a slow but steady decline from 21 per 100,000 in 2000 to 14.5 per 100,000 population by 2010. For the period 2000 to 2010, the reported incidence rate for TB in the Canadian-born non-Aboriginal population remained steady at approximately 1 per 100,000 population.
Population denominators obtained from Statistics Canada
In addition to differential incidence rates by population group, TB case patterns also reveal pronounced disparities based on geographic region within Canada. In 2010, incidence rates ranged from a low of 0.7 per 100,000 population in Prince Edward Island to a high of 106.1 per 100,000 population in Northern territories combined (Figure 6). The three most populous provinces in Canada, namely British Columbia, Ontario and Quebec, with 75% of the population, accounted for 69% of all TB cases in 2010.
Figure 6. Reported TB incidence rates by province/territory, Canada, 2010
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The bar-graph shows the reported TB incidence rate by province and territory for the year 2010. The horizontal axis shows the ten provinces as well as the North which combines the rates for Northwest Territories, Nunavut and Yukon. The vertical axis displays the rate per 100,000 population. For the ten provinces, the rates are all below 11 per 100,000. The rate for the North, however, is many time higher at 105 cases per 100,000 population.
Population denominators obtained from Statistics Canada
Distribution of TB cases by population group also varies significantly by jurisdiction. As depicted in the graphs below (Figure 7), the majority of cases in Alberta, British Columbia, Ontario and Quebec occurred in foreign-born individuals, whereas in Manitoba, Saskatchewan and the Northern territories most cases occurred largely in Aboriginal people. These varied geographic patterns in part reflect differences in the populations among jurisdictions: there are more foreign-born individuals in Ontario, Quebec, British Columbia and Alberta in particular, whereas Aboriginal communities make up a higher proportion of the general population in the prairies and in the North.
Figure 7. Number of reported TB cases by population group and province/territory in Canada, 2010Footnote *
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The bar-graph shows the breakdown of the number of reported TB cases by province, across origin groups (from top to bottom: foreign-born, Canadian-born Aboriginal and Canadian born non-Aboriginal). For Alberta, BC, Ontario and Quebec, the majority of cases were foreign-born. In Manitoba, Saskatchewan and the North, the majority of cases were Canadian-born Aboriginals.
Population denominators obtained from Statistics Canada
Tuberculosis in Canadian-born Aboriginal Peoples
While the greatest number of cases is reported among foreign-born individuals, the reported incidence rate has consistently been highest among Canadian-born Aboriginal individuals over the past decade (Figure 8).
"The Constitution Act of 1982 recognizes three major groups of Aboriginal Peoples in Canada: Indian (more commonly referred to as First Nations), Inuit and Métis. First Nations (on- and off-reserve) and Inuit account for the vast majority of incident cases of TB in Aboriginal peoples in Canada."Footnote 7 From 2001 to 2010, the rate of TB was highly variable in the Inuit population and peaked in 2010 at approximately 200 cases per 100,000 population. In contrast, the rates were relatively stable for First Nations (on- and off-reserve) and Métis (Figure 8).
Figure 8. Reported TB disease incidence rates in Canada by population group, 2001-2010
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This graph shows the trend lines for the reported incidence rate of TB cases by Aboriginal group (Inuit, First Nation on–reserve, First Nation off–reserve, and Métis) and the trend line for the Canadian-born non-Aboriginal population, for the years 2001 to 2010. First Nations (on- and off-reserve) and Inuit account for the majority of incident cases of TB in Aboriginal peoples in Canada. From 2001 to 2010, the rate of TB was highly variable in the Inuit population. In 2003 the reported incident rate for the Inuit population was 22.1 per 100,000 population. The reported incidence rate for the Inuit rose to approximately 200 cases per 100,000 population in 2010. The graphs show that the reported incidence rates for First Nations (on- and off-reserve) were relatively stable over time with the First Nation on-reserve population having slightly high incidence rate (range 21.6 to 30.4 per 100,00 population) than the First nations off-reserve population (range 18.6 to 27.8 per 100,000 population).
The burden of TB disease among Aboriginal populations varies by jurisdiction. In terms of both overall cases as well as rates, TB cases in Aboriginal individuals in 2010 were significantly higher in Nunavut, Saskatchewan and Manitoba (Figure 9).
Figure 9. Distribution of active TB cases and incidence rates for Aboriginal populations, 2010
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The bar-graph shows the breakdown of the number of reported TB cases and the reported incidence rates for the Canadian-born Aboriginal population by province, for 2010. The horizontal axis shows the reporting provinces and territories, the left-hand vertical axis shows the number of reported cases and the right-hand vertical axis shows the incidence rate per 100,000 population. The majority of the Aboriginal cases were reported from Manitoba (76), Nunavut (99) and Saskatchewan (70). The highest reported incidence rate was reported from Nunavut at 333.0 per 100,000.
Figure 10. TB cases and incidence rates among Canadian-born-Aboriginal Populations by age group, 2010
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This bar graph shows the breakdown of the TB cases reported among the Canada-born Aboriginal populations in 2010 by age-group (< 5, 5-14, 15-24, 25-34, 35-44, 45-54, 55-64, 65-74 and 75+) with the bars representing the number of reported cases and the trend line showing the rate per 100,000 population. The majority of the reported cases in Aboriginal individuals was reported in adolescents and young adults between the ages for 15 and 44 years of age. A substantial number of cases in Canadian-born Aboriginal individuals was reported in children under the age of 15, and the incidence rate was much higher than that seen in other Canadian populations. The highest reported incidence rate, 69 per 100,000 population, was reported for those individuals 75 years of age and older.
The majority of all cases in Aboriginal individuals were reported in adolescents and young adults in the 15-44 year age groups (Figure 10). A substantial number of cases in Canadian-born Aboriginal individuals were reported in children, and the incidence rate was much higher than that seen in other Canadian populations. This suggests ongoing transmission in some Aboriginal communities.
Tuberculosis in the Foreign-born Population
While the proportion of all TB cases in Canada among the foreign-born has increased significantly in the past 40 years, the annual number of reported cases has not changed substantially, averaging 1,000 cases per year. Over the past 11 years, however, the incidence rate has declined slowly but steadily, reaching 13.3 per 100,000 in 2010 (Figure 8). Of the foreign-born TB cases reported in Canada from 2000 to 2010 for which the date of arrival was known, 11% were reported within the first year of arrival, 22% within the second year of arrival and 44% within 5 years (Figure 11).
Figure 11. Reported foreign-born TB cases in Canada, 2000-2010: time from arrival in Canada to diagnosis, in years
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The bar graph shows the number of foreign born cases reported by the time difference between the year of arrival into Canada and the year in which the TB was diagnosed. The horizontal axis shows the years from arrival into Canada to year of diagnosis and runs from 0 to 54 years. The vertical axis shows the number of reported cases. Of the foreign-born TB cases reported in Canada between 2000 and 2010 for which the date of arrival was reported, 11% were reported within the first year of arrival, 22% by the second year of arrival and 44% within 5 years.
Each foreign-born TB case was assigned to a WHO TB epidemiologic regionFootnote 8 on the basis of the individual's country of birth. (These regions differ from the WHO's standard administrative regions). Figure 12 depicts changes over time in the distribution of the region of origin of all foreign-born TB cases reported in Canada. During the period 1970 to 2010 the proportion of cases from established market economiesFootnote & decreased, whereas the proportion of cases reported from the Western Pacific and South-East Asia regions increased.
Figure 12. Percentage of reported foreign-born TB cases in Canada by WHO TB epidemiologic region, 1970-2010
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The line graph shows the changing trends in the percentage of foreign-born cases by epidemiological regions as set out in the STOP TB partnership/WHO TB (African Region – high HIV prevalence countries, Africa Region – low HIV prevalence countries, Americas, Eastern Europe Region, Eastern Mediterranean Region, Established Market Economies, Central European Region, South East Asia Region, and Western Pacific Region). During the period 1970 to 2010 the percentage of cases from established market economies decreased, whereas the percentage of cases reported from the Western Pacific and South-East Asia regions increased. In 2010, 42% of reported cases in the foreign-born population were born in the Western Pacific Region followed and an additional 25% were born in the South East Asia Region.
Changing immigration patterns account for some of the changes to this distribution. In addition to increased migration to Canada of people from African, Asian and Pacific regions, these regions also have the highest TB incidence rates (Table 1), which results in a corresponding shift in Canada's distribution. Rates within Canada are calculated as the number of cases in Canada among people born in a certain region divided by the total population in Canada born in that region. Rates within Canada are significantly lower across people from all WHO regions compared with respective rates within the regions. People in Canada who emigrated from the two African RegionsFootnote + (high and low HIV prevalence), as well as the South-East Asia Region and the Western Pacific Region, show the highest rates, mirroring patterns seen within the regions themselves. Almost one-half of TB cases typically occur within 5 years of arrival in Canada.
|WHO regionFootnote 1.1||Reported rate in Canada 2010||WHO estimated TB incidence rate in regions, 2010Footnote 1.2|
|Africa, High HIV Prevalence||37.4||306.3|
|Africa, Low HIV Prevalence||21.5||194.4|
|American Region – Latin American Countries||7.0||42.9|
|Established Market Economies and
The majority of reported TB cases in 2010 (64%) were diagnosed as pulmonary TB. Peripheral lymph node was the second most commonly reported site, at nearly 13% of cases in the same year. Slight differences were observed when comparing the three origin groups. A greater proportion of cases in Aboriginal individuals were due to primary disease, and a greater proportion of foreign-born individuals received a diagnosis of peripheral lymph node TB (Figure 13).
Figure 13. Percentage of reported cases by diagnostic site and origin in Canada, 2010
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The bar chart shows the percentage of reported TB cases by diagnostic site (primary, pulmonary, other respiratory, miliary, central nervous system, peripheral lymph node and other) across origin groups (Canadian-born Aboriginal represented by the white bar, Canadian-born non-Aboriginal represented by the rose bar and foreign-born represented by the red bar). Also included is the overall percentage of cases by diagnostic site for all cases reported in Canada. Sixty-four percent of all reported TB cases in 2010 were diagnosed with pulmonary TB. Peripheral lymph node was the second most commonly reported site, at nearly 13% of cases in the same year. Slight differences were observed when comparing the three origin groups. A greater proportion of cases in Aboriginal individuals were diagnosed with primary disease, and a greater proportion of foreign-born individuals received a diagnosis of peripheral lymph node TB.
The majority of TB cases in Canada are diagnosed by culture confirmation. In 2010, 1,261 (80%) were culture-confirmed. Figure 14 presents data on the proportion of pulmonary TB cases that were smear-positive (indicating a higher level of infectivity) and smear-negative, and the proportion of cases for which laboratory data were not reported. Between 2000 and 2010, an average of 41% of all reported pulmonary TB cases were smear-positive, 34% were reported as smear-negative, and for 25% laboratory microscopy results were not reported.
Figure 14. Percentage of pulmonary cases by sputum smear microscopy result: Canada, 2000-2010
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The area graph shows data for the pulmonary TB cases diagnosed between 2000 and 2010. The data show the percentage of reported cases diagnosed with active pulmonary TB by sputum smear microscopy results (sputum smear positive, sputum smear negative or sputum smear unknown). Between 2000 and 2010, on average 33% of all reported pulmonary cases were smear negative, 41% were reported as smear positive and lab microscopy results were not reported for 26% of pulmonary cases.
Canada's national HIV/AIDS and TB surveillance systems have their own limitations regarding their ability to estimate TB-HIV coinfection. However, information on HIV status is increasingly included in TB cases reported to the CTBRS. In 2000, HIV status was reported for only 16% of TB cases, but that figure had increased to 40% in 2010 (Figure 15). Among cases for which HIV status was reported, the coinfection rate in 2010 was 5%. This percentage is possibly biased towards HIV testing among those individuals with known risk factors for HIV infection. In the unlikely event that these were the only coinfected cases, the overall coinfection rate was 2%. The true coinfection rate probably lies somewhere in the 2%-5% range. The WHO has estimated the Canadian rate in 2007 to be 5.7%Footnote 9. Underreporting imposes serious limitations on the interpretation of HIV-TB coinfection in Canada.
Figure 15. Percentage of reported TB cases by HIV status, Canada, 1997-2010
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The stacked bar graph shows data on the HIV status for all reported TB cases diagnosed between 1997 and 2010. For each year the bars show the percentage of cases for which HIV status was unknown, the percentage that was positive and the percentage that was negative. Between 1997 and 2010 the percentage of cases for which the HIV status (positive or negative) was reported as unknown has decreased from 94% of cases to 59% of cases. In 2010, the HIV status for 60% of the reported cases remained unknown, 2% were positive and 38% of all cases were reported to be HIV negative.
Data and trends on TB drug resistance in Canada are detailed in Chapter 8, Drug-Resistant Tuberculosis.
Treatment and Case Outcomes
Of 1,658 cases of active TB disease diagnosed in 2009, 1,599 (96%) had a treatment outcome. Of these, 1,399 (87%) were deemed cured or treatment completed, 129 (8%) died before or during treatment, and 31 (2%) transferred out of Canada at some point during their treatment with final outcome unknown. Of the remaining 3% of cases reporting an outcome, 18 absconded and were lost to follow-up, 1 had a treatment failure, and treatment was discontinued for 1 case because of adverse reactions to the medications. For the 4% of the total number of reported cases in 2009 for which treatment was not completed, treatment was ongoing in 42 cases and was unknown at the time of writing in the remaining 17 cases.
Drug regimen was reported for 1,249 reported cases in 2009. Of these, 89% were reported to have received three or more drugs. Fifty-nine percent of the individuals were reported to have received directly observed therapy (DOT), 32% self-administered therapy and 8% unspecified or other.
Between 2000 and 2009, 8.6% of diagnosed cases were reported to have died before or during treatment. TB was reported to have been the cause of death in 18% of these cases and contributed to but was not the underlying cause of death in an additional 41% of the cases. TB was reported not to have contributed to death but was an incidental finding in 28% of cases. For 12% of cases, the cause of death was not reported. However, it is important to note that identification of the precise cause of death can be inaccurate, and the WHO recommends that the most important indicator is death (of any cause) during treatment.
Between 2000 and 2009, of those individuals with a diagnosis of active TB disease, 1,429 were reported to have died before or during treatment. Males accounted for 63% of these deaths and had a median age of 73 years at the time of death. Females accounted for 37% and had a median age of 74 years at the time of death. Ten percent had had a previous episode of TB disease. HIV status was known for 17% of all deaths during this period; of these, 39% were HIV-positive. Of the 1,429 TB-attributed deaths reported, 170 (12%) were found to have TB on postmortem examination.
Summary of Salient Trends
Both the overall rate and annual number of reported cases of TB continue to slowly decline in Canada. Nevertheless, pronounced disparities are observed in certain population groups and in several geographic regions. The high proportion of cases in foreign-born individuals presents unique challenges, in particular because of changing demographic patterns. Also of concern are the continued high rates observed among Aboriginal peoples born in Canada, particularly in Inuit communities.
TB partners in Canada aim to reduce the national TB incidence rate, and in particular to reduce the burden of TB disease among Canadian-born Aboriginal peoples and the foreign-born. In order to achieve reduction in these key populations, prevention and control interventions should target those determinants of health that contribute to the disease. The public health community has long recognized that economic, social, cultural and environmental factors play a role in TB infection and disease. As detailed in this chapter, certain Canadian populations experience greater risk of TB than others. In addition to foreign-born and Aboriginal communities in Canada, those who are incarcerated or homeless also show higher rates, as outlined in subsequent chapters of the Standards. There are numerous determinants of health that relate to TB, which include education, employment, physical environment, social support, access to health care, personal health practices and cultureFootnote 7. Addressing the underlying determinants of health is universally recognized by TB experts as being an integral component of the response, both in Canada as well as globallyFootnote 10 Footnote 11.
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