Paediatric tuberculosis in Canada 

TUBERCULOSIS IN CANADA 2000
512 KB in PDF Format Only

Cat. H49-108/2000
ISBN 0-662-67074-4

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Special Report of the
Canadian Tuberculosis Committee

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Background

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Overview

Tuberculosis continues to be a significant cause of morbidity and mortality for children throughout the world. In Canada, TB in children steadily declined from 1970 to 1988 with a brief resurgence through the 1990s. The majority of children with TB acquire the disease from adults with whom they are in close contact. Although TB can have a profound impact on the affected children and their families, paediatric TB has a limited influence on the transmission of the disease, as children are rarely infectious. However, the occurrence of TB in children is a marker for recent and ongoing transmission of the disease in a population.¹

Methods 

TB case data reported to the Canadian Tuberculosis Reporting System (CTBRS) from 1970 to 2001 were examined.  The reporting system is designed to capture information on every new active or relapsed case of TB occurring in Canada in all provinces and territories. Paediatric cases were defined as all cases occurring in individuals younger than 15 years of age. Cases within the CTBRS meet the Canadian Tuberculosis Standards case definition.² Population estimates by origin were obtained from Statistics Canada, and Indian and Northern Affairs Canada (1991-2001). Ethnic origin for this report is defined as Status Indian, Non-status Indian/Metis and Inuit (Aboriginal), Canadian-born non-Aboriginal, and foreign-born. If ethnic origin was reported as unknown, the record was excluded from analysis. Diagnostic site follows the hierarchy established by the Surveillance Sub-committee of the Canadian Tuberculosis Committee and includes primary, miliary, meninges/central nervous system, respiratory (includes pulmonary and other respiratory), peripheral lymph node and other sites (see Appendix I, Technical Notes for ICD-9 codes related to this hierarchy). 

Epidemiology of TB among children in Canada 

The number of reported TB cases in children younger than 15 years of age declined from 430 in 1970 to 109 in 2001, an average annual decline of 4%. The incidence of TB disease in children has also decreased, from 6.6 per 100,000 in 1970 to 1.9 per 100,000 in 2001. An increase in the number of cases and incidence of TB among children was observed for the period of 1989 to 1999, mostly attributable to cases diagnosed in the Canadian-born Aboriginal population; however, this increasing trend has since reversed (Figures SR-1 and SR-3). 

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Figure SR-1
Paediatric tuberculosis cases and incidence in Canada, 1970–2001

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From 1970 to 2001, 45% of TB in children occurred in the under 5 age category. Younger children were more likely to present with meningeal, miliary or primary TB, whereas older children more frequently presented with other non-pulmonary sites and respiratory TB (Figure SR-2). By sex, TB in children is uniformly distributed between males and females (51% male; 49% female). 

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Figure SR-2
Paediatric tuberculosis by diagnostic site and age, 1970–2001

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TB disease case counts and rates were significantly higher among children of Aboriginal origin than among Canadian born non-Aboriginal and foreign-born populations (Table SR-A). Over time, the number of reported cases has measurably decreased among the Canadian-born non-Aboriginal population, remained constant in the foreign born and decreased, although less dramatically, in the Canadian-born Aboriginal group (Figure SR-3). 

Table SR-A  : Distribution and incidence (2001) of paediatric tuberculosis cases by origin in Canada: 1970–2001
Origin	Number of cases, 1970-2001	Percentage of cases, 1970-2001	Number of cases, 2001	Percentage of cases, 2001	Percentage of paediatric population, 2001	Incidence rate per 100,000, 2001
Canadian-born Aboriginal	3,574	53.5	61	56.0	6.8	15.3
Canadian-born non-Aboriginal	2,429	36.4	28	25.7	78.5	0.6
Foreign born	679	10.2	20	18.3	14.6	2.3
TOTAL	6,682	100	109	100	100	1.9
Note: totals may not always equal 100 because of rounding.

Figure SR-3
Paediatric tuberculosis by origin, 1970–2001

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Summary 

Infected children represent a large proportion of the pool from which future TB cases arise. Continued TB diagnosis in children is indicative of ongoing transmission of infection. The majority of paediatric TB cases in Canada occur in children of Aboriginal origin. By origin, TB disease in children mirrors the overall presentation of the disease in Canada over the past 30 years. TB case reporting has fallen dramatically among the Canadian-born non-Aboriginal population, less so among the Aboriginal population and has remained constant among the foreign-born. 

TB disease in children is compounded by the difficulty in obtaining an accurate diagnosis and in differentiating between infection and disease. The most important manifestations of the disease are miliary and meningeal disease given the high morbidity and mortality associated with these forms. 

Directions 

The most likely factor contributing to this ongoing burden of disease in children is lack of access to health resources in remote areas, leading to slow identification and examination of infectious cases and close contacts.  Ultimately, controlling TB in children is dependent upon the control of TB in adults.  The prompt identification of pulmonary TB in adults followed by prompt and complete treatment as well as investigation of contacts is essential for interrupting transmission of the disease.  Adequate resources and infrastructure must be in place to provide these necessary services.  Continued education of health care professionals is also crucial to maintain awareness and suspicion of TB as a possible diagnosis in children who fail to gain weight or whose lower respiratory tract infections fail to resolve despite appropriate treatment.³ 

Members: Dr. V. Hoeppner (Chair); Dr. M. Baikie; Dr. C. Balram; Ms. C. Case; Dr. E. Ellis (Executive Secretary); Dr. R.K. Elwood (Past Chair); Ms. P. Gaba; Dr. B. Graham; Dr. B.  Gushulak; Ms. C. Helmsley; Dr. E.S. Hershfield; Ms. R. Hickey; Dr. A. Kabani; Dr. B. Kawa; Dr. R. Long; Dr. F. Stratton; Ms. S. Black; Dr. L. Sweet; Dr. T.N. Tannenbaum. 

This report was prepared by Ms. Melissa Phypers, Senior Epidemiologist, Tuberculosis Prevention and Control, Health Canada. 

Reference List 

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1. Tuberculosis in children. In: Reichman LB, Hershfield ES, eds. Tuberculosis: A comprehensive approach. New York: Marcel Dekker, Inc, 2000: 553–5. 
2. Long R. ed. Canadian tuberculosis standards, 5^th edition. Ottawa: Canadian Lung Association, 2000. 
3. Tuberculosis in childhood. In: Davies PDO, ed. Clinical tuberculosis. London: Chapman and Hall, 1996: 219.