Tuberculosis in Canada 1999

EXECUTIVE SUMMARY

As of April 1, 1999, the territory of Nunavut began reporting as a new jurisdication. TB incidence rates were similar to that of the neighbouring Northwest Territories. Seven of the reporting jurisdictions had case rates below the national rate (Alberta, New Brunswick, Newfoundland, Nova Scotia, Prince Edward Island, Quebec and the Yukon Territory). The three most populous provinces (Ontario, Quebec and British Columbia) which collectively make up 75% of Canada's population, accounted for 73% of the total number of reported cases. Compared with the previous year, five reporting jurisdictions (Nova Scotia, Ontario, Alberta, the Yukon Territory and the Northwest Territories) reported a decrease in case numbers and rates. Slightly increased rates were reported for Newfoundland, New Brunswick, Quebec, Saskatchewan and Manitoba) (Table B).

By age group, individuals in the age category 25 to 34 years made up the largest number of reported cases, accounting for 18% of the total. However, the corresponding case rate of 7.4 per 100,000 for this age group was surpassed by the age-specific rates of 11.1 and 15.9 per 100,000 for those in the older age groups of 65 to 74 and greater than 74 years respectively (Appendix II, Table 2A). Canadian-born non-Aboriginal cases were relatively older (median 58 years) than foreign-born (median 41 years) and Canadian-born Aboriginal TB cases (median 30 years).

The presentation of tuberculosis by gender revealed a larger number of reported cases among males (992 cases, 6.6 per 100,000) than among females (815 cases, 5.3 per 100,000) (Appendix II, Tables 2B, 2C).

TB incidence continues to be highest among the foreign-born population. In 1999, cases in foreign-born individuals accounted for 64% of all reported cases. The proportion of all TB cases that were Canadian-born non-Aboriginal, Canadian-born Aboriginal and foreign-born in 1989 were 33%, 20% and 47% respectively. By 1999, these proportions had decreased among Canadian-born non-Aboriginals and Canadian-born Aboriginals to 18% and 17% respectively, whereas among the foreign-born the proportion had increased to 64%.

The provinces of British Columbia and Ontario reported the highest percentage of foreign-born cases (74% and 85% respectively). In other jurisdictions foreign-born cases accounted for over half of all reported cases (Alberta, 60%; Quebec, 57%). In the Northwest Territories, Saskatchewan and Manitoba, cases of Canadian-born Aboriginals contributed all or a large proportion of reported cases (the Yukon Territory and Nunavut 100%, the Northwest Territories 91%; Saskatchewan 87%; Manitoba 60%) (Table C; Appendix II, Table 6).

Overall, respiratory TB (please see Appendix I, Technical Notes for definition) was the most frequently reported main diagnostic site, representing 65% of reported cases in 1999 (Appendix II, Table 4). A larger proportion of Canadian-born non-Aboriginal cases were reported as respiratory TB (73%) compared with that among both the Canadian-born Aboriginal and foreign-born cases (56% and 65% respectively). TB of the peripheral lymph nodes was the second most commonly reported diagnostic site (13%), with 42% of these cases occurring in foreign-born individuals who originated in the WHO Western Pacific Region. Among the Canadian-born Aboriginal cases, primary TB accounted for the most significant proportion (30%) of all notifications after respiratory TB (Appendix II, Table 10).

1,500 of the 1,807 reported cases (83%) were laboratory confirmed. Of the 1,171 respiratory cases, 43% were smear (microscopy) positive and 85% were culture positive (Appendix II, Table 14).

Of the 1,807 cases reported in 1999, 1,476 cases were culture positive. Of these, 89% had no resistance to TB drugs. 7.2% were resistant to one drug and the remaining 3.8% showed patterns of resistance to two or more drugs prescribed. The most common type of monoresistance was resistance to Isoniazid (INH) accounting for 39.5% of all reported resistance. Multi-drug resistant TB (please see Appendix I, Technical Notes for definition) accounted for < 1% of the drug resistant cultures reported (Appendix II, Table 15).

The majority of reported cases (76%) were detected through presentation of symptoms to a medical professional (Appendix II, Table 17).

Of the 1,807 cases diagnosed in 1999, 129 were reported to have died in the same year. TB was reported as the underlying cause of death for 26 cases (20%). For 52 cases (40%), TB was reported as contributing to death, but not as the underlying cause (Appendix II, Table 23). It should be noted that the number of reported TB related deaths is an underestimate, as it includes only known deaths occurring in the same year as the diagnosis at the time of reporting.

HIV reporting has shown slight improvement from previous reporting years. In 1997 and 1998 HIV status was unknown for 94.3 and 91.6% of the total cases reported respectively. In 1999, HIV status was unknown for 87% of reported cases (Appendix II, Table 25).

1999, marks the first year that Tuberculosis in Canada is reporting treatment outcome data (1998 cases). Of the 1,791 cases reported in 1998, treatment outcome data was reported for 809 cases. Of these, 80% were reported as being culture negative or having completed treatment. The majority of individuals placed on TB drug therapy in Canada received treatment as per the Canadian Tuberculosis Standards. Drug regimen reporting was complete for 807 cases of which 86% (696 cases) were treated with three or more anti-tuberculosis drugs.

The 1999 Tuberculosis in Canada annual report is a publication of Tuberculosis Prevention and Control (TBPC), Centre for Infectious Disease Prevention and Control, Public Health Agency of Canada, Health Canada. Reports of new active and relapsed tuberculosis cases are reported to TBPC through the Canadian Tuberculosis Reporting System (CTBRS) from the ten provinces and three territories.

This publication is notably different than previous annual reports published by TBPC. In addition to presenting data for cases reported to CTBRS that were diagnosed in 1999, this report also includes inaugural treatment outcome data for cases diagnosed in 1998. The report contains information on the overall TB case counts and case rates for selected demographic and clinical characteristics. The report outlines case and treatment outcome data for the following:

• province/territory
• gender
• age
• birthplace
• activity status
• main diagnostic site
• bacillary status
• method of detection
• immigration status
• HIV status
• patterns of drug resistance
• treatment outcomes
• treatment drug regimens.

Appendices to the report include: technical notes on the methodology of the report including the definition of terms (Appendix I), data tables (Appendix II), estimated incidence of TB from 23 high-burden countries (as designated by the World Health Organization, Appendix III), population estimates for 1999 (Appendix IV), the tuberculosis case reporting form and the treatment outcome reporting form (Appendix V).

The annual reports on tuberculosis morbidity have undergone and will continue to have revisions in format and content from year to year. It is our goal to continue to adapt and improve this publication in response to changes in the epidemiology and treatment of tuberculosis. We welcome any comments on the content or format of this document.

HOW TO REACH US

For more information, copies of this report or other related reports, please contact:

        Tuberculosis Prevention and Control
        Centre for Infectious Disease Prevention and Control
        Public Health Agency of Canada
        Health Canada
        Room 0108B, Brooke Claxton Building
        Tunney's Pasture, Ottawa, Ontario K1A 0K9

        Internal Postal Address: 0900B-1

        Telephone:     (613) 941-0238
        Facsimile:     (613) 946-3902

The following figures, tables and explanatory text were prepared by:

        Penny Nault
        Tuberculosis Database Manager
        Tuberculosis Prevention and Control

        Melissa Phypers, MSc
        Acting Chief
        Tuberculosis Prevention and Control

ACKNOWLEDGEMENT

The authors would like to acknowledge the Provincial/Territorial Tuberculosis Programs and their teams for their contribution to and participation in the Canadian Tuberculosis Reporting System (CTBRS).

The authors would also like to thank the Scientific Publication and Multimedia Services Unit, Public Health Agency of Canada, for its assistance in preparing this report.

Published by authority of the Minister of Health

© Minister of Public Works and Government Services Canada 2002

This publication can be made available in alternative formats upon request.