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Pulmonary Medicine
Volume 2013, Article ID 828939, 11 pages
Review Article

Risk Factors for Tuberculosis

1School of Public Health and Community Medicine, The University of New South Wales, Kensington, Sydney, NSW 2052, Australia
2Infectious Diseases Research and Training Centre, Department of Medicine-I and Infectious Diseases, Christian Medical College, Vellore, Tamil Nadu, India

Received 7 October 2012; Revised 27 December 2012; Accepted 5 January 2013

Academic Editor: Anete Trajman

Copyright © 2013 Padmanesan Narasimhan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The risk of progression from exposure to the tuberculosis bacilli to the development of active disease is a two-stage process governed by both exogenous and endogenous risk factors. Exogenous factors play a key role in accentuating the progression from exposure to infection among which the bacillary load in the sputum and the proximity of an individual to an infectious TB case are key factors. Similarly endogenous factors lead in progression from infection to active TB disease. Along with well-established risk factors (such as human immunodeficiency virus (HIV), malnutrition, and young age), emerging variables such as diabetes, indoor air pollution, alcohol, use of immunosuppressive drugs, and tobacco smoke play a significant role at both the individual and population level. Socioeconomic and behavioral factors are also shown to increase the susceptibility to infection. Specific groups such as health care workers and indigenous population are also at an increased risk of TB infection and disease. This paper summarizes these factors along with health system issues such as the effects of delay in diagnosis of TB in the transmission of the bacilli.