Paediatric tuberculosis among the foreign-born: utility of the Canadian TB immigration medical surveillance programme

BACKGROUND: There are few data on the utility of screening paediatric immigrants for tuberculosis (TB) in low TB burden countries. OBJECTIVE: To evaluate the utility of the Canadian immigration medical examination and TB Medical Surveillance (TBMS) for detecting paediatric TB disease. DESIGN: A 10-year population-based retrospective cohort study of foreign-born children (ages 0-10 years) and adolescents (ages 11-17 years) immigrating to Ontario, Canada, using linked immigration and public health databases. RESULTS: Among 232 169 individuals (median follow-up of 5.7 years), active TB was diagnosed at or after immigration in 125 cases (20 children and 105 adolescents), at an overall rate of 54/100 000 (14/100 000 children, 116/100 000 adolescents). All cases originated from 34 countries. Active TB was diagnosed in 0/419 children and 10/418 adolescents referred for medical surveillance, representing only 8.0% of all cases. TBMS referrals were correlated with a previous diagnosis of TB (κ = 0.8) and were driven by country of origin (e.g., hazard ratio 31.2 for the Philippines). Rates of pre-immigration TB diagnosis varied considerably among high TB burden countries. CONCLUSIONS: The current Canadian system detects little TB disease, and reveals very different rates of pre-immigration paediatric TB diagnosis in different high TB burden countries. These data provide a basis for improving TB screening strategies for immigrants to low TB burden countries.