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.