Association between passive smoking and infection with Mycobacterium tuberculosis in children

Tuberculosis and smoking are both significant public health problems. The association between passive smoking and Mycobacterium tuberculosis infection is not well documented. The objective of this study was to examine the influence of passive smoking on M. tuberculosis infection in children.

A community survey was conducted in 15% of addresses in 2 adjacent low-income suburbs in Cape Town, South Africa. All children (< 15 years of age) and their adult household members residing at these addresses were included in the study. Children underwent tuberculin skin testing. An induration of > or = 10 mm was considered to define M. tuberculosis infection. Passive smoking was defined as living in the household with at least 1 adult who smoked for at least 1 year. Random-effects logistic regression analysis was performed, and odds ratios were adjusted for age, presence of a patient with tuberculosis in the household, average household income, and clustering at the household level.

Of 1344 children, 432 (32%) had a positive tuberculin skin test. Passive smoking was significantly associated with M. tuberculosis infection in the unadjusted analyses but not in the adjusted analyses. In the 172 households with a patient with tuberculosis, passive smoking was significantly associated with a positive tuberculin skin test but not in the 492 households without a patient with tuberculosis.

Passive smoking is associated with M. tuberculosis infection in children living in a household with a patient with tuberculosis. More studies are needed to confirm this observation, but the possible association is a cause of great concern, considering the high prevalence of smoking and tuberculosis in most developing countries.