Smokers seen twice as likely to develop active TB

Mon Aug 24, 2009 7:45am EDT
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By Tan Ee Lyn

HONG KONG (Reuters) - A study in Taiwan has found that smokers are twice as likely to develop active tuberculosis compared to people who have never smoked, prompting calls for policymakers to be tougher on smoking.

The study tracked nearly 18,000 people in Taiwan representing a general population for more than three years.

"We found a two-fold increase in the risk of active TB in current smokers compared with never-smokers (those who have never smoked)," wrote the lead author Hsien-Ho Lin, a postdoctoral research fellow from Brigham and Women's Hospital in Boston.

One in three people in the world is infected with TB but 90 percent of these will remain latent infections. The remaining 10 percent will develop active TB and fall sick at some point in their lives because of weak immune systems. For example, many people who are infected with HIV/AIDS fall sick and die from TB.

Among the 17,699 participants in the Taiwan study, 3,893 were current smokers, 552 were former smokers and 13,254 had never smoked. There were 57 new cases of active TB by the end of the three-year study.

After factoring in considerations like sex, age, living in a crowded home, household income, marital status, alcohol use and employment, the researchers still found a higher risk of active TB among current smokers.

"Based on our analysis, 17 percent of incident TB cases in this population were attributable to smoking," they wrote.

Smokers may have reduced ability to fight intruding viruses and bacteria, such as TB, in their lungs, the experts wrote.   Continued...

<p>Xie Yung-cheng, 54, smokes a cigarette at his sleeping area inside a carpark in Taiwan, November 21, 2007. REUTERS/Nicky Loh</p>