title: Risk factors for tuberculosis.
abstract: 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.
authors.affiliation: School of Public Health and Community Medicine, The University of New South Wales, Kensington, Sydney, NSW 2052, Australia.
authors.forename: Padmanesan
authors.initials: P
authors.lastname: Narasimhan
authors.forename: James
authors.initials: J
authors.lastname: Wood
authors.forename: Chandini Raina
authors.initials: CR
authors.lastname: Macintyre
authors.forename: Dilip
authors.initials: D
authors.lastname: Mathai