Although, smoking per se does not cause the TB disease, experts warn that those infected with the TB bacteria run a greater risk of developing the disease if they are smokers, reports Sade Oguntola.

It may sound far-fetched that smoking can lead to severe brain damage. That smokers may exacerbate the problem of malnutrition because they tend to finance their habit by dipping into the family purse may also sound outrageous. But, the finding that smoking increases the risk of developing active tuberculosis (TB) disease, which would require daily intake for eight months to get rid of this disease, is really a cause for concern.

Although, smoking per se does not cause the TB disease, a new report by researchers from Brigham and Women’s Hospital in Boston, stated that those infected with the TB bacteria run a greater risk of developing the disease if they are smokers.

The researchers, when they compared the likelihood of active TB among ever, never, and current smokers, found that smokers are two times more at risk of developing active TB compared with people who never smoked. Infectious tuberculosis is known as active TB. There was a strong association between increased risk and the number of cigarettes smoked per day, years of smoking, and pack-years.

Interestingly, they also found that younger smokers were more likely than smokers older than 65 years to develop active TB, relative to their non-smoking counterparts.

The report analysed data on smoking data and exposure to second-hand smoke at home from almost 17,000 people, aged 12 years and older in Taiwan taking part in that country’s National Health Interview Survey.

About 3,900 were current smokers(people who were smokers at the time of interview) and about 13,250 had never smoked. Active TB occurred in 24 current smokers, compared with 30 in those who had never smoked.

Meanwhile, the researchers took into consideration factors such as sex, age, living in a crowded home, household income, marital status, alcohol use and employment, which could have affected the outcome of the finding of the study, published in the American Journal of Respiratory and Critical Care Medicine.

They noted, “Based on our analysis, 17 per cent of incident TB cases in this population were attributable to smoking. When extrapolated to the national population, this translated into 2,841 cases among the 16,580 reported in Taiwan in 2005.”

Dr. John Osho, Coordinator, Disease Control, Oyo State Ministry of Health, Ibadan, explained that the person who smokes has greater affinity to develop active TB disease since smoking is a very important predisposing factor to active TB disease. “The reasons are not far fetched. Tobacco smokers inhale smoke and the tar content of the smoke gets into the lungs. The tar causes some inflammatory response in the lungs. It is this inflammatory response that weakens the lung tissues. Basically, what TB needs to thrive and destroy the lung tissue is an unhealthy lung where it can thrive.”

Even though, everyone that leaves in a TB endemic environment like Nigeria has been exposed to the TB germ, he stated that the implication is that when people smoke, the possibility of the germ manifesting itself is higher.

Dr. Osho stated that people who were passive smokers might equally be affected, depending on the amount of smoke they were exposed to and the duration of exposure. He declared, “In the case of a passive smoker, the amount of smoke and the duration of exposure, all these things matter. However, passive smoking does not put at a level of risk that is comparable with what obtains in actual smokers. “

Meanwhile, Dr. Osho declared that not all smokers would end up having TB disease. “Not necessarily in medicine, you cannot say that all smokers would end up with TB disease. However, such people may be prone to other airway diseases

He opined that TB, all over the world had been declared by the World Health Organisation(WHO) as a global epidemic and so, the focus and funding to combating TB, AIDS and Malaria globally under the Global Funds for TB, AIDS and Malaria.

Dr. Wole Lawal, Coordinator, TB/Leprosy Programme, at the Oyo State Ministry of Health, explained that as advertisements of cigarettes read, smoking in dangerous to health. According to him, one of the dangers of smoking was that it reduces the ability of the lining of the airway to filter infection and lead to activation of latent TB germ in the body.

Dr. Lawal added that given that addicted smokers may easily substitute balanced meals with smoking, this could affect their body’s resistance to diseases as well as predisposing them to developing active TB. “Some of the things we tell our patients that are on anti-tuberculosis medicines or confirmed with TB is that they must stop smoking so that the habit would not further complicate their problem. This is because smoke is an irritant to the lung and as such would make the person that is exposed to it produce more sputum.

He pointed out that smoke, irrespective of its source was bad for the body as it could also predispose to allergic diseases like asthma and chronic airway diseases.

Several studies have shown that smoking is a risk factor for developing the tuberculosis disease. But there has not been any large-scale study in the general population to understand this association as most studies looked at high-risk individuals to understand how smoking makes a person develop the disease.

Tuberculosis (TB), which has 9.3 million new cases and claimed the lives of some 1.8 million in 2007, is still a leading cause of death in the world. One in every three individuals in the world is infected with TB; only 90 per cent, however, will develop active TB at some point in their lives due to their weak immune systems.

One in three people in the world is infected with TB but 90 percent of these will remain latent infections. The remaining 10 per cent 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.

Only a doctor can diagnose tuberculosis whose signs and symptoms include persistent cough, constant fatigue, weight loss, loss of appetite, fever, coughing up blood and night sweats. A skin test will be performed. If the person reacts to the test, the person has only been exposed to the disease. It does not mean that the person is infectious or has tuberculosis.

The researchers wrote, “Smokers may have reduced ability to fight intruding viruses and bacteria, such as Mycobacterium tuberculosis, the bacteria responsible for tuberculosis, in their lungs. When these normal defence mechanisms are compromised, the development of TB might ensue upon exposure to the TB pathogen.”

Based on the result of the study, they urged policy makers and authorities to add tobacco cessation as part of their programmes for controlling the spread of tuberculosis. Campaigns should also reach others affected by the smoke that is likely to benefit from the cessation of smoking among those around them.

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