Smoking 'linked to TB'
2005-06-30 07:48
Paris - Smoking seems to boost the risk of tuberculosis, possibly by weakening the lungs' resistance to the TB bacterium, a South African study published on Thursday says.
Researchers at Stellenbosch University asked 2 400 adults about their smoking habits and got them to undergo a skin test for TB.
To get a level playing field, the researchers took the volunteers' age, sex, educational level, fat and income into account.
Of 1 300 people who were current or ex-smokers, 82% tested positive for tuberculosis, whereas among the 1 100 people who had never smoked, the rate was 70%.
The reason for the smoking-TB link is unclear, the researchers say.
However, they point to previous studies that show smoking suppresses the activity of protective white-blood cells in the lungs and blood, and this may hamper the immune system's ability to combat the TB bug.
The study appears in Thorax, a specialist journal of the British Medical Association (BMA).
Testing positive for the tuberculosis bacterium does not mean by itself that someone has tuberculosis disease.
Many people can carry the bacteria but do not fall sick from it or spread it.
TB is an infectious disease of the lung that is usually spread by coughing or sneezing.
But repeated or prolonged exposure to someone with TB disease is generally necessary before a person will fall sick.
Cramped housing and prisons in poor countries are typical incubators for the disease.