Tobacco smoking, TB, HIV and chronic obstructive pulmonary disease (COPD) are all burgeoning problems in resource poor settings. The evidence of their potentially devastating effects on global public health is increasing and they require a coordinated approach for control. These diseases all occur in predominantly resource-poor countries. They are perpetuated by poverty and inadequate resources and their control and management require coordinated approach for control, said delegates at the 40th Union World Conference on LungHealth, in Cancun, Mexico.
Statistically, there is 1 TB-related death that takes place every 18 seconds, 1 HIV death every 16 seconds and 1 smoking-related death every 13 seconds. The enormous public challenge posed by the combined epidemics of tobacco smoking, HIV, TB and COPD, is undoubtedly alarming. But is there a link between TB, HIV, COPD and tobacco smoking? Do they increase the risk of each other?
"At the beginning of 21st century we really are facing convergence of several epidemics like HIV, TB, COPD and tobacco smoking among others" said Richard N van Zyl-Smit work works with Lung Infection and Immunity Unit, Division of Pulmonology and UCT Lung Institute, Department of Medicine, University of Cape Town, South Africa.
"Tobacco smoking is unquestionably the primary risk factor for COPD. The importance of "total burden of inhaled particles" (occupational, household, environmental) is increasing" said Richard.
"Smokers have two fold higher risk of developing active TB disease" said Dr Madhukar Pai from McGill University and Montreal Chest Institute in Canada. Dr Pai was referring to three meta-analysis studies from 2007/2008. "Tobacco smokers have 2 times more risk of dieing of TB" added Dr Pai, referring to the data from India. India has enormous tobacco use and COPD rates, and also the highest TB burden in the world. "It is not a universal estimate, and is population specific" cautioned Dr Pai, outlining the need for more research on the association between TB, tobacco smoking, COPD and HIV. "There is very little data to study association between TB and passive smoking" said Dr Pai. However there are studies to show that passive smoking escalates risk of developing active TB disease by three times. "How can passive smoking have higher risk (three times) for developing active TB disease than active smoking (two times), so we do need more data in this regard" said Dr Pai.
Tobacco smoke increases the risk of pneumonia, influenza, menningococcal meningitis, among others. Evidence is accumulating that smoking is a risk factor for TB. However there is no published data on the cellular interactions of tobacco smoke and mycobacterium tuberculosis, said Richard.
At least 15 more studies have been published since the three major meta-analyses in 2007/2008. All studies report a positive association between tuberculosis and tobacco smoking. Studies also show that current male smokers have a higher risk for active TB disease than former smokers. In a study conducted in India, 900 non-medical staff monitored 1.1 million people for 3 years for cause of death taking place in this population. TB was the biggest cause of death reported in this study in India, and 66% of those who died of TB during the study, were active smokers.
The risk to develop active TB disease is higher when tobacco smoking is combined with alcohol.
"Mortality rates, particularly from Asian countries suggest that there is an urgent need to target TB patients for smoking cessation interventions" said Dr Pai. However he stressed that tobacco cessation should be encouraged regardless in all disciplines of medicine because of proven public health outcomes.
The second edition of the International Standards of Tuberculosis Care (ISTC), which is an official component of the WHO Global Stop TB Strategy also mentions tobacco smoking cessation among other measures to improve TB treatment outcomes. The ISTC standard 17 says: "This plan should include assessment of and referrals for treatment of other illnesses with particular attention to those known to affect treatment outcome, for instance care for diabetes mellitus, drug and alcohol treatment programs, tobacco smoking cessation programs, and other psychosocial support services, or to such services as antenatal or well baby care.
Dr Donald Enarson stressed that tobacco smoking cessation is an important part of the comprehensive tobacco control programme, and not the only part. So all components of the comprehensive tobacco control measures should be implemented for improving public health outcomes. Dr Enarson was referring to MPOWER report from Tobacco Free Initiative (TFI) of WHO which outlines the MPOWER package, a set of six key tobacco control measures that reflect and build on the WHO Framework Convention on Tobacco Control (FCTC, global tobacco treaty). Another delegates remarked that MPOWER is in line with the global tobacco treaty - FCTC - and we should be demanding implementation of the treaty to which governments have committed to enforce. The WHO FCTC is the first public health and corporate accountability treaty, said a delegate from India. Comprehensive tobacco control programmes can yield major public health outcomes, as 30% of male TB patients die of tobacco smoking.
Although lethal association between tobacco smoking, COPD and TB was becoming clear, we needed more discussion on association between smoking with HIV. "Tobacco smoke increases the risk of human papiloma virus (HPV) and HPV increases the risk of HIV" said Richard in response to a question on the link between HIV and smoking.
Kristina Crothers from Department of Internal Medicine, Yale School of Medicine in USA, shed more light on this association with HIV. She was referring to long term complications of HIV and progression to AIDS, which does get influenced by the above risk factors.
TB continues to be the biggest cause of mortality among people living with HIV (PLHIV) worldwide. However, HIV related long-term complications get aggravated by noxious agents which include tobacco smoke. The risk to develop pulmonary infections and respiratory tract colonization is also upped. The history of childhood illnesses, low socio-economic status, malnutrition among PLHIV does increase their vulnerability to further severe the HIV-related long-term complications. All these are contributing factors for PLHIV to develop chronic lung disease, and COPD in case of smokers, among other conditions that include fibrosis, pulmonary hypertension and lung cancer.
Kristina cited smoking prevalence among PLHIV in northern America. Although tobacco smoking prevalence among general population in USA is 22%, yet the tobacco smoking prevalence goes up among PLHIV to 54%.
In India, in a study conducted by Tuberculosis Research Centre at Madurai, the following results were reported: 66% of PLHIV men were smokers.
In another study, those PLHIV who reported 12 pack years of smoking, had 37% of emphysema, and those who reported 25 pack years of smoking, had 46% of emphysema.
"HIV is associated with chronic lung disease, particularly COPD" said Kristina. "This chronic lung disease can substantially contribute to morbidity and mortality" added Kristina. However long term impact of HIV infection on lung health is unknown, said she.
Studies show that smoking may impact progression to AIDS among PLHIV, said Kristina.
Although more research and data may further clarify the lethal synergy between the epidemics of TB, HIV, tobacco smoking and COPD, among other public health challenges, there is no doubt that collaboration between different single disease or health programmes will be truly beneficial and have major public health outcomes.
Bobby Ramakant, CNS
(The author is a World Health Organization (WHO) Director-General's WNTD Awardee (2008), writes extensively on health and development and manages the Stop-TB eForum. He is a Fellow of Citizen News Service (CNS) Writers' Bureau. Email: [email protected], website: www.citizen-news.org)
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