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Open Access Highly Accessed Research article

Force of tuberculosis infection among adolescents in a high HIV and TB prevalence community: a cross-sectional observation study

Keren Middelkoop12*, Linda-Gail Bekker12, Hua Liang3, Lisa DH Aquino1, Elaine Sebastian1, Landon Myer45 and Robin Wood12

Author Affiliations

1 Desmond Tutu HIV Centre, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa

2 Department of Medicine, University of Cape Town, Cape Town, South Africa

3 Department of Biostatics and Computational Biology, University of Rochester Medical Center, Rochester, USA

4 Centre for Infectious Diseases Epidemiology & Research, School of Public Health & Family Medicine, University of Cape Town, Cape Town, South Africa

5 International Centre for AIDS Care and Treatment Programs and Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, USA

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BMC Infectious Diseases 2011, 11:156  doi:10.1186/1471-2334-11-156

Published: 1 June 2011

Abstract

Background

Understanding of the transmission dynamics of tuberculosis (TB) in high TB and HIV prevalent settings is required in order to develop effective intervention strategies for TB control. However, there are little data assessing incidence of TB infection in adolescents in these settings.

Methods

We performed a tuberculin skin test (TST) and HIV survey among secondary school learners in a high HIV and TB prevalence community. TST responses to purified protein derivative RT23 were read after 3 days. HIV-infection was assessed using Orasure® collection device and ELISA testing. The results of the HIV-uninfected participants were combined with those from previous surveys among primary school learners in the same community, and force of TB infection was calculated by age.

Results

The age of 820 secondary school participants ranged from 13 to 22 years. 159 participants had participated in the primary school surveys. At a 10 mm cut-off, prevalence of TB infection among HIV-uninfected and first time participants, was 54% (n = 334/620). HIV prevalence was 5% (n = 40/816). HIV infection was not significantly associated with TST positivity (p = 0.07). In the combined survey dataset, TB prevalence was 45% (n = 645/1451), and was associated with increasing age and male gender. Force of infection increased with age, from 3% to 7.3% in adolescents ≥20 years of age.

Conclusions

We show a high force of infection among adolescents, positively associated with increasing age. We postulate this is due to increased social contact with infectious TB cases. Control of the TB epidemic in this setting will require reducing the force of infection.