Associations between tobacco and tuberculosis.

The association between smoking and tuberculosis (TB) has been investigated since 1918. Both passive and active exposure to tobacco smoke have been shown to be associated with tuberculous infection and with the transition from being infected to developing TB disease. The association between smoking and developing TB disease (without separating the risk of transition from being exposed to being infected and that from being infected to developing TB disease) has been reported substantially. Smoking affects the clinical manifestations of TB. It has been shown that ever smokers are more likely to have cough, dyspnoea, chest radiograph appearances of upper zone involvement, cavity and miliary appearance, and positive sputum culture, but are less likely to have isolated extra-pulmonary involvement than non-smokers. Smoking has been found to be associated with both relapse of TB and TB mortality. There appears to be enough evidence to conclude that smoking is causally associated with TB disease. Patients with TB need and should receive counselling and assistance in stopping smoking.