title: Smoking and tuberculosis: an association overlooked.
abstract: OBJECTIVE
  This article discusses the role of smoking as a risk factor for tuberculosis. A review of the evidence that has been documented is presented.
  
  
  METHODS
  Relevant articles in the medical literature derived from searching the Medline database (1966 to present) with key terms 'smoking' and 'tuberculosis'. The bibliographies of all papers thus located were searched for further relevant articles.
  
  
  RESULTS
  On searching the database, a total of 12 studies were found. A search of the bibliographies yielded four more articles. Sixteen studies published between 1956 to the present were included in this review. The evidence suggests that smoking could be considered as an important risk factor for the development of tuberculosis. Not only does active smoking appear to heighten the chances of contracting pulmonary tuberculosis, smokers also seem to be at an increased risk for extrapulmonary tuberculosis. Exposure to environmental tobacco smoke in children seems to enhance the hazards of acquiring tuberculosis. Increased tuberculin reactivity, in a dose-dependent manner, was recorded in smokers as compared to non-smokers.
  
  
  CONCLUSIONS
  Although an association between smoking and tuberculosis appears evident, prospective studies would help to confirm the evidence and to highlight this noxious association. Nevertheless, smoking should be considered as an important risk factor for tuberculosis.
authors.affiliation: Department of Respiratory Medicine, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India.
authors.forename: V
authors.initials: V
authors.lastname: Maurya
authors.forename: V K
authors.initials: VK
authors.lastname: Vijayan
authors.forename: A
authors.initials: A
authors.lastname: Shah
mesh_terms: D016021:Epidemiologic Studies; D006801:Humans; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology; D014397:Tuberculosis, Pulmonary / Q000209:etiology*