The association between secondhand smoke exposure and risk of developing active tuberculosis in individuals with latent tuberculosis infection: a systematic literature review.

Background: Tuberculosis is one of the leading causes of death from infectious diseases in the world, with approximately 25% of the global population having latent tuberculosis infection. Secondhand smoke exposure has been recognised as a significant risk factor in the development of active Tuberculosis in individuals with latent tuberculosis infection.

Study design and methods: This study used the Systematic Literature Review method based on PRISMA guidelines. Relevant articles published between 2014-2024 were identified through PubMed, ProQuest, and Scopus databases using related keywords. A total of 13 articles met the inclusion criteria for analysis.

Results: Secondhand smoke exposure significantly increases the risk of latent tuberculosis infection conversion to active Tuberculosis, with a stronger effect in vulnerable groups such as children and individuals who are in close contact with active Tuberculosis patient and live in the same household with heavy smokers. This risk of exposure to secondhand smoke follows a dose-response pattern, where longer duration and higher intensity of exposure directly increase the likelihood of Tuberculosis activation in individuals with latent tuberculosis infection. The biological mechanisms involve immune suppression and lung damage caused by toxic particles in the tobacco smoke, which weaken the body's defenses against Mycobacterium tuberculosis and facilitate the progression of latent tuberculosis infection to active Tuberculosis. Therefore, reducing exposure to secondhand smoke is important to mitigate its impact on active Tuberculosis progression.

Conclusion: Secondhand smoke exposure has been consistently shown to increase the risk of developing active Tuberculosis in individuals with latent tuberculosis infection. To support the global Tuberculosis elimination programme, concerted efforts are needed to reduce exposure to secondhand smoke, especially in individuals with latent tuberculosis infection.