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A5378 - Prevalence of Tuberculosis Infection Among South African Adolescents
Author Block: E. W. Bunyasi1, H. Geldenhuys1, H. Mulenga1, J. Shenje1, A. Luabeya1, M. Tameris1, F. Ratangee1, K. Vollenhoven1, M. d. Kock1, E. Nemes1, H. Mahomed2, V. Rozot1, R. Wood3, T. Scriba1, J. Andrews4, M. Hatherill1; 1Dept of Pathology, University of Cape Town, Cape Town, South Africa, 2Division of Community Health, Stellenbosch University, Stellenbosch, South Africa, 3The Desmond Tutu HIV Centre, University of Cape Town, Cape Town, South Africa, 4Division of Infectious Diseases and Geographic Medicine, Stanford University, Stanford, CA, United States.
Rationale To measure changes in adolescent prevalence of latent tuberculosis (TB) infection (LTBI) between 2005-2015, in order to evaluate medium-term impact of TB control measures on Mycobacterium tuberculosis transmission, in a South African region where annual TB disease notifications fell 34% from 1,038 to 682 per 100,000 over the same decade. Methods We compared baseline data from a cohort study (2005-2007) and a vaccine trial (2014-2015), which enrolled adolescents from the same 8 South African high schools. LTBI was defined by positive QuantiFERON®-TB Gold In-Tube test. Results We analysed data from 4,880 adolescents between 2005-2007 and 1,968 adolescents between 2014-2015, when average LTBI prevalence was 43.8% (95% confidence interval (CI) 28.4-59.1) vs 48.5% (CI: 41.1-55.8), respectively. Age-specific LTBI prevalence increased between the ages of 12-18 years by 13% only in lower socio-economic quintile schools, in which average LTBI prevalence was 54% vs 53% in the two periods, consistent with stable rates of M.tuberculosis transmission before and during adolescence (Figure 1). LTBI prevalence did not increase with age in highest socio-economic quintile schools, but average LTBI prevalence increased from 20% to 38% between the two periods, consistent with increased risk of M.tuberculosis transmission, limited to the period prior to school entry. Conclusions Adolescent LTBI prevalence remained high and constant over a decade, suggesting M. tuberculosis transmission to children was not impacted in the medium term by effective TB control efforts. Trends in adolescent LTBI prevalence should be interpreted in the context of socio-demographic factors that affect risk of transmission before and during adolescence.