Mycobacterium tuberculosis Infection in Close Childhood Contacts of Adults with Pulmonary Tuberculosis is Increased by Secondhand Exposure to Tobacco

Tuberculosis prevention: current strategies and future directions

BACKGROUND

An estimated one fourth of the world's population is infected with Mycobacterium tuberculosis, and 5-10% of those infected develop tuberculosis in their lifetime. Preventing tuberculosis is one of the most underutilized but essential components of curtailing the tuberculosis epidemic. Moreover, current evidence illustrates that tuberculosis manifestations occur along a dynamic spectrum from infection to disease rather than a binary state as historically conceptualized. Elucidating determinants of transition between these states is crucial to decreasing the tuberculosis burden and reaching the END-TB Strategy goals as defined by the WHO. Vaccination, detection of infection, and provision of preventive treatment are key elements of tuberculosis prevention.

OBJECTIVES

This review provides a comprehensive summary of recent evidence and state-of-the-art updates on advancements to prevent tuberculosis in various settings and high-risk populations.

SOURCES

We identified relevant studies in the literature and synthesized the findings to provide an overview of the current state of tuberculosis prevention strategies and latest research developments.

CONTENT

We present the current knowledge and recommendations regarding tuberculosis prevention, with a focus on M. bovis Bacille-Calmette-Guérin vaccination and novel vaccine candidates, tests for latent infection with M. tuberculosis, regimens available for tuberculosis preventive treatment and recommendations in low- and high-burden settings.

IMPLICATIONS

Effective tuberculosis prevention worldwide requires a multipronged approach that addresses social determinants, and improves access to tuberculosis detection and to new short tuberculosis preventive treatment regimens. Robust collaboration and innovative research are needed to reduce the global burden of tuberculosis and develop new detection tools, vaccines, and preventive treatments that serve all populations and ages.

"Inhaling hazards, exhaling insights: a systematic review unveiling the silent health impacts of secondhand smoke pollution on children and adolescents

The health risks of smoking are widely known, but the impact of secondhand smoke on children and adolescents is often underestimated. Despite efforts to reduce smoking, exposure to secondhand smoke remains a significant public health concern, especially for young individuals. This systematic review aims to explore the health impacts of secondhand smoking on children and adolescents. Following PRISMA guidelines, 18 eligible studies from 8 countries published between 2015 and 2023 were identified through PubMed, SCOPUS, and Web of Science databases. Findings revealed that passive smoking is associated with respiratory issues like asthma and respiratory infections in children and adolescents aged 4 months to 18 years. Significant correlations were found between asthma severity and cotinine levels, a marker of passive smoking. Additionally, metabolic issues, cardiovascular effects, and ophthalmological changes, and alterations in neurocognitive functions, were noted. Urgent public health interventions are needed to reduce smoking prevalence and protect this vulnerable demographic.

Tuberculosis Infection in Children and Adolescents

The burden of tuberculosis (TB) in children and adolescents remains very significant. Several million children and adolescents are infected with TB each year worldwide following exposure to an infectious TB case and the risk of progression from TB infection to tuberculosis disease is higher in this group compared to adults. This review describes the risk factors for TB infection in children and adolescents. Following TB exposure, the risk of TB infection is determined by a combination of index case characteristics, contact features, and environmental determinants. We also present the recently recommended approaches to diagnose and treat TB infection as well as novel tests for infection. The tests for TB infection have limitations and diagnosis still relies on an indirect immunological assessment of cellular immune response to Mycobacterium tuberculosis antigens using immunodiagnostic testing. It is recommended that TB exposed children and adolescents and those living with HIV receive TB preventive treatment (TPT) to reduce the risk of progression to TB disease. Several TPT regimens of similar effectiveness and safety are now available and recommended by the World Health Organisation.

Review of Pediatric Tuberculosis in the Aftermath of COVID-19

In 2014, the World Health Organization developed the End Tuberculosis Strategy with the goal of a 95% reduction in deaths from tuberculosis (TB) by 2035. The start of the COVID-19 pandemic and global lockdown has had a major impact on TB awareness, screening, diagnosis, and prompt initiation of treatment, inevitably leading to a significant setback. We explore pediatric tuberculosis through the lens of the COVID-19 era, investigating how COVID-19 has impacted pediatric TB cases in different regions of the world and what the implications are for management moving forward to mitigate these effects. Furthermore, in light of recent findings showing how exposed infants and children are at higher risk than we thought of contracting the disease, greater attention and resources are needed to prevent further downward trends.

Tobacco Smoking and Second-Hand Smoke Exposure Impact on Tuberculosis in Children

Little is known about whether second-hand smoke (SHS) exposure affects tuberculosis (TB). Here, we investigate the association of cigarette smoke exposure with active TB and latent TB infection (LTBI) in children, analyzing Interferon-Gamma Release Assays’ (IGRAs) performance and cytokine immune responses. A total of 616 children from contact-tracing studies were included and classified regarding their smoking habits [unexposed, SHS, or smokers]. Risk factors for positive IGRAs, LTBI, and active TB were defined. GM-CSF, IFN-γ, IL-2, IL-5, IL-10, IL-13, IL-22, IL-17, TNF-α, IL-1RA and IP-10 cytokines were detected in a subgroup of patients. Being SHS exposed was associated with a positive IGRA [aOR (95% CI): 8.7 (5.9–12.8)] and was a main factor related with LTBI [aOR (95% CI): 7.57 (4.79–11.94)] and active TB [aOR (95% CI): 3.40 (1.45–7.98)]. Moreover, IGRAs’ sensitivity was reduced in active TB patients exposed to tobacco. IL-22, GM-CSF, IL-5, TNF-α, IP-10, and IL-13 were less secreted in LTBI children exposed to SHS. In conclusion, SHS is associated with LTBI and active TB in children. In addition, false-negative IGRAs obtained on active TB patients exposed to SHS, together with the decrease of specific cytokines released, suggest that tobacco may alter the immune response.

Association between indoor air pollution, tobacco smoke and tuberculosis: an updated systematic review and meta-analysis

OBJECTIVE

This study aims to further quantify evidence of the association between exposure to indoor air pollution (IAP), tobacco smoke etc., on the one hand and the risk of contracting tuberculosis (TB) on the other.

STUDY DESIGN

This was a systematic review and meta-analysis of articles published between June 2014 and February 2020 in PubMed, Web of Science, among others.

METHODS

We only included studies that controlled for confounders, screened both the exposed and unexposed study participants, and passive smoking studies that limited the study population to non-smokers. Quality of studies was assessed using the Newcastle-Ottawa scale. The analysis was conducted using STATA, and pooled effect sizes were calculated using the random-effects model, and heterogeneity was tested for using the Cochran Q test and I2 statistic.

RESULTS

A total of 26 articles were included in the final analysis. There was an increased risk of contracting TB among people exposed to IAP (risk ratio [RR] = 1.68, 95% confidence interval [CI] 1.108-2.542). We also observed a two-fold increase in the risk of contracting TB from exposure to secondhand tobacco smoke (RR = 2.15, 95%CI 1.419-3.242). Tobacco smoking doubled the risk of contracting TB (RR = 2.67, 95%CI 2.017-3.527). Furthermore, studies that used microbiological tests showed a higher RR compared to those that used other TB diagnostic methods.

CONCLUSION

Exposure to IAP and secondhand tobacco smoke increases the risk of contracting TB. Various disease prevention campaigns should include IAP awareness and encourage a shift to cleaner sources of energy.

Epidemiological, Mycobacteriological, and Clinical Characteristics of Smoking Pulmonary Tuberculosis Patients, in Lambaréné, Gabon: A Cross-Sectional Study

Gabon carries a high burden of both tuberculosis (TB) and smoking. This study examines the disease characteristics of smoking pulmonary TB patients in Lambaréné. We interviewed adult pulmonary TB patients in Lambaréné, between March 2016 and April 2019. Clinical and biological patient characteristics were collected. Bivariate and logistic regression analyses were performed to assess factors associated with smoking. The mean age of patients included was 31 years (±13). The proportion of smokers in our study was 30% (89/295). Smoking was significantly associated with patient-related diagnostic delay (adjusted odds ratio [AOR] = 8.18; 95% CI = 3.67-19.56), a higher number of pulmonary TB signs and symptoms (AOR = 2.74; 95% CI = 1.18-6.73), and a higher sputum mycobacterial load (AOR = 3.18; 95% CI = 1.33-8.11). The prevalence of smoking among TB patients is high, and leading to aggravated disease as compared with controls. Our study findings suggest that smoking patients should be regularly screened for TB, to reduce diagnostic delay and TB transmission within community. Smoking cessation activities should be included in the national TB control program in Gabon.