Objective: To determine the prevalence of tuberculosis (TB) infection in Year 8 schoolchildren (aged 12-14 years) in Sydney.
Design: Cross-sectional survey.
Setting: 22 inner city Sydney secondary schools.
Participants: 2290 Year 8 school children enrolled in 1992.
Outcome measures: Distribution of Mantoux test reaction size and proportion of children who were Mantoux positive (i.e., having Mantoux reaction > or = 15 mm with previous Bacille Calmette-Guérin vaccination; > or = 10 mm without).
Results: Of the 2290 children, 1836 (81%) were screened and 1801 Mantoux reactions were read. Ten per cent of children were Mantoux positive--27% of foreign-born children and 2% of Australian-born children (relative risk 16.7, 95% confidence interval 10.6-26.4). Two children were found to have active TB disease.
Conclusion: There is a high prevalence of primary (non-contagious) TB infection in children aged 12-14 years in inner Sydney, mostly confined to children born overseas. Thus there is a large pool of infected children at risk of developing active (contagious) adult-type TB disease in the future. This public health problem should be addressed by identification and treatment of those infected.