Tuberculosis in Canada 2013: Pre-Release

In Canada, 1,640 new active and re-treatment TB cases were reported in 2013, for a corresponding incidence rate of 4.7 per 100,000 population (Table 1A). This is comparable to both the number of TB cases reported in 2012 (n = 1,699) and the incidence rate for 2012 (4.9 per 100,000 population). The annual number of reported TB cases and the corresponding annual incidence rates have remained relatively stable between 2003 and 2013.

In 2013, British Columbia, Ontario, and Quebec, which together make up 75% of the total Canadian population, continued to account for the majority of reported TB cases (68%) in Canada (Table 1A).

In 2013, the incidence rates in the Atlantic provinces (New Brunswick, Newfoundland and Labrador, Nova Scotia, and Prince Edward Island), Alberta, Ontario and Quebec were all equivalent to or below the Canadian rate of 4.7 per 100,000 population. No TB cases were reported from Prince Edward Island in 2013. The incidence rates in all other provinces and territories were higher than the Canadian rate. Nunavut has consistently had the highest incidence rate; in 2013, the incidence rate was 143.3 per 100,000 population (Table 1A). The 2013 incidence rate was lower than the 2012 rate, at 230.5 per 100 000 population, and represented a difference of 29 fewer cases compared to 2012 (Table 1A). Between 2003 and 2013 there was little change in the overall distribution of cases by province or territory.

Similarly, there was little change in the overall distribution of cases by sex, age group, and diagnostic classification (Table 1B, Table 1C, Table 2 and Table 3). In 2013, males continued to account for a larger percentage of reported cases than females. Males accounted for 902 of the 1,640 reported cases (55% of the total number reported) which corresponds to an overall incidence rate of 5.2 per 100,000 population (Table 1B). In comparison, females accounted for 738 cases (45% of all reported cases) for a corresponding incidence rate of 4.2 per 100,000 population (Table 1C).

In 2013, individuals aged 25 to 34 years old represented the largest percentage of reported cases at 16%. However, the highest incidence rate was observed for those aged 75 years or older, at 9.3 per 100,000 population. In 2013, 7% of reported cases were less than 15 years of age (Table 4).

Foreign-born individuals and Canadian-born Aboriginal people continued to be disproportionately represented among reported cases of TB in 2013. Data on origin was available for 1,611 (98%) of the 1,640 cases reported in 2013. The foreign-born population, which represented approximately 22% of the total Canadian population in 2013, accounted for 71% of reported cases of known origin (n = 1,146), with a corresponding incidence rate of 14.8 per 100,000 population. Canadian-born Aboriginal people made up 4% of the total Canadian population in 2013 but accounted for 19% (n = 309) of reported cases of known origin, with a corresponding incidence rate of 19.9 per 100,000 population. Canadian-born non-Aboriginal people accounted for the lowest percentage of reported cases at 10% (n = 155) with a corresponding incidence rate of 0.6 per 100,000 population (Table 5).

The distribution of TB cases across origin groups varied by province and territory. In 2013, the majority of cases (> 60%) reported by Alberta, British Columbia, Ontario, and Quebec were foreign-born. Canadian-born Aboriginal people accounted for the majority (> 65%) of reported cases in Manitoba and Saskatchewan. In the territories (Northwest Territories, Nunavut, and Yukon), almost all (98%) reported cases were Canadian-born Aboriginal people (Table 5).

Canadian-born Aboriginal people comprise three distinct populations: First Nations, Inuit and Métis people. In 2013, of the 309 reported Canadian-born Aboriginal cases, 200 (65%) were First Nations, 91 (29%) were Inuit and 18 (6%) were Métis. The incidence rate among the Métis was 3.3 per 100,000 population, which was lower than the overall Canadian incidence rate of 4.7 per 100,000 population. By comparison, the incidence rate in First Nations, at 21.8 per 100,000 population, was almost five times the overall Canadian rate. The highest incidence rate, however, was in the Inuit population, at 154.2 per 100,000 population (Table 5).

Based on their country of birth, foreign-born cases were grouped into one of nine epidemiological regions as defined by the STOP-TB Partnership/World Health Organization^{Reference 2}. Individuals born in the Western Pacific region countries accounted for the highest percentage of reported foreign-born cases in Canada (42%). Of these cases, 75% were from China and the Philippines. However, the highest incidence rate, at 48.5 per 100,000 population, was observed for foreign-born individuals from the AFR-High region, primarily Ethiopia (Table 5).

Active TB disease is classified as either respiratory or non-respiratory. Respiratory TB includes pulmonary TB, TB of the pleura, the intrathoracic or mediastinal lymph nodes, or of the larynx, nasopharynx, nose or sinuses. Primary disease^{Reference i} is also captured under the respiratory classification. Non-respiratory TB refers to all other disease sites^{Reference 3}. As in recent years, 77% of cases were diagnosed with respiratory TB and 23% with non-respiratory TB in 2013 (Table 3, Table 6). Pulmonary TB, including TB of the lungs and conducting airways, accounted for the majority (67%) of reported cases in 2013 (Table 6).

Treatment Outcomes for 2012

Partial or complete treatment outcome data were available for 1,614 (95%) of the 1,699 reported cases of active TB disease in 2012. Of the remaining cases, treatment was reported as on-going for 72 and treatment outcome data were unknown for 12 (Table 7).

Of the 1,614 cases reported in 2012 for which treatment outcome data were available:

• 1,409 (87%) were reportedly cured or had completed treatment;
• 128 (8%) died before or during treatment;
• 26 (2%) moved outside of Canada before completing treatment;
• 24 (1%) had absconded or were lost to follow-up;
• 7 (0.4%) cases stopped treatment due to an adverse reaction, and
• 1 case reported treatment failure.

For the remaining 20 cases (1%) for which treatment outcome data were available, the treatment outcome was reported as "other." Of these, seven cases were non-compliant with the prescribed treatment regimen and no further information was available for the remaining 13 cases.

Conclusion

As in 2012, preliminary data from 2013 indicate that there were no notable changes in the number of reported cases of TB or in the overall incidence rate in Canada. Similarly, no changes were noted in the distribution of cases by province or territory, or by age group and sex. Foreign-born individuals continued to account for the majority of reported TB cases, and the incidence rates per 100,000 population remained highest among Canadian-born Aboriginal people. Pulmonary TB remained the most commonly reported site of disease in 2013, and available treatment outcome data for cases reported in 2012 indicated that 87% of cases had been cured or had completed treatment.

The findings from this analysis are provisional and will likely change over time. Updated case counts and incidence rates for 2013 will be presented in the next iteration of the Tuberculosis in Canada surveillance report.

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References

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