Epidemiologic link between tuberculosis and cigarette/biomass smoke exposure: Limitations despite the vast literature

Abstract

The geographic overlap between the prevalence of cigarette smoke (CS) exposure and tuberculosis (TB) in the world is striking. In recent years, relatively large number of studies has linked cigarette or biomass fuel smoke exposure and various aspects of TB. Our goals are to summarize the significance of the known published studies, graphically represent reports that quantified the association and discuss their potential limitations. PubMed searches were performed using the key words 'tuberculosis' with 'cigarette', 'tobacco', 'smoke' or 'biomass fuel smoke.' The references of relevant articles were examined for additional pertinent papers. A large number of mostly case-control and cross-sectional studies significantly associate both direct and second-hand smoke exposure with tuberculous infection, active TB, and/or more severe and lethal TB. Fewer link biomass fuel smoke exposure and TB. While a number of studies interpreted the association with multivariate analysis, other confounders are often not accounted for in these analyses. It is also important to emphasize that these retrospective studies can only show an association and not any causal link.We further explored the possibility that even if CS exposure is a risk factor for TB, several mechanisms may be responsible. Numerous studies associate cigarette and biomass smoke exposure with TB but the mechanism(s) remains largely unknown. While the associative link of these two health maladies is well established, more definitive, mechanistic studies are needed to cement the effect of smoke exposure on TB pathogenesis and to utilize this knowledge in empowering public health policies.

A Systematic Review of the Prevalence and Pattern of Imaging Defined Post-TB Lung Disease

“…Uncertainty therefore remains about the rate and drivers of recovery/deterioration in those with post-TB lung damage. Factors influencing the progression of lung damage may include modifiable exposures such as smoking, biomass fuel[ 69 , 70 ], and ongoing respiratory tract infections[ 71 ]. Further research in this area may inform strategies to prevent decline in this group.…”

Biomass smoke as a risk factor for chronic obstructive pulmonary disease: effects on innate immunity

“…63 Moreover, some studies reported an association between tuberculosis cases and biomass fuel smoke exposure compared with exposure to cleaner forms of fuels. 64 Despite the link between chronic exposure to BS and the occurrence of respiratory infections being based primarily on epidemiological data, few experimental studies in animals have reinforced this idea. Thus, Hatch et al showed a significantly increased mortality on mice with streptococcal pulmonary infection instilled with carbonaceous particles.…”

E-cigarettes: Effects in phagocytosis and cytokines response against Mycobacterium tuberculosis

“…It is noteworthy that countries with a high incidence of TB tend to also have an elevated proportion of smokers [3]. The link between TB and cigarette smoke has already been suggested since 1918 and it has been confirmed by several epidemiological studies [4,5]. There is evidence that cigarette smoke is a risk factor for TB, aiding the infection, the progression to the active disease and the severity of the illness [6,7].…”