Smoking feeds India TB scourge

<http://news.bbc.co.uk/1/hi/health/3151839.stm>
Friday, 15 August, 2003, 00:23 GMT 01:23 UK 

Smoking feeds India TB scourge

Hundreds of thousands of TB deaths in India can be directly linked to
smoking, say expert researchers. 

Scientists from the Epidemiological Research Centre in Chennai
calculated that half the male tuberculosis deaths in India stemmed
from tobacco. 

If you have TB, it can lie dormant in your lungs - but smoking can
encourage an active, and often fatal, infection. 

Three-quarters of those diagnosed with TB in India would not have done
so if they were not smokers. 

TB remains a major killer in South Asia. 

In India alone approximately 400,000 people a year die from the lung
infection. 

The Chennai researchers, working in collaboration with the University
of Oxford, found that half these deaths were caused by smoking, and
were perhaps therefore preventable. 

Early deaths 

They compared 43,000 men who had died from various diseases in the
late 1990s with the health habits of more than 35,000 living men. 

More than 4,000 of the deaths were from TB - but if there had been no
smoking involved, the researchers calculated that only 2,000 of these
deaths would have happened. 

Dr Vendhan Gajalakshmi, from the Chennai research centre, said:
"Almost 200,000 people a year in India die from TB because they smoked
- and half of these are still only in their 30s, 40s or early 50s when
they die." 

Sir Richard Peto, from Oxford University, said: "In some parts of the
world the main way smoking kills people is by damaging the lung's
defences against chronic TB infection. 

"Our study indicates that in rural India about 12% of smokers, but
only 3% of non-smokers, die prematurely from TB." 

However, this is far from being a problem just for smokers. 

Immune weakness 

If smoking leads to an active infection, that person also gains the
ability to infect other people - regardless of whether they smoke or
not. 

Approximately a billion people worldwide are carrying the bacterium
that causes TB in their lungs, but in most cases their natural
defences suppress it. 

It is only when a chink appears in that immune defence that the actual
illness surfaces and a threat to life emerges. 

That could either be caused by smoking, or by another infection such
as HIV, which reduces immune defences. 

This is why so many people with HIV eventually fall prey to TB. 

The paper was published on Friday in the Lancet medical journal.