Biological, Social, and Environmental Factors in TB

1. Tuberculosis (TB) Epidemiology in Spain

• In 2021, Spain reported 3,754 TB cases, with a notification rate (NR) of 7.61 per 100,000; this marked a 2.18% decline from 2020 and a 28.07% reduction from 2015.
• Spain surpassed its TB control goals by 2020, reducing overall TB rates by 26.5% and pulmonary TB by 6% annually, maintaining its status as a low-incidence TB country.
• Higher TB rates were reported in northern regions—Ceuta, Galicia, Catalonia, Rioja, and the Basque Country—while the Canary Islands and parts of southern Spain had lower rates.
• TB incidence was 1.7 times higher in men than women, with nearly half of the cases among foreign-born individuals, typically younger than native-born cases; TB mortality was 2.6 times higher in males.
• Foreign-born TB cases primarily came from high-burden countries (Morocco, Romania, Bolivia, Peru, Pakistan); over half had lived in Spain for over 10 years, while only 13% were recent arrivals (<2 years).

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2. Geographic, Seasonal, and Environmental Factors in TB

• A clear north–south gradient exists in TB incidence across Spain, with the highest rates in northern provinces (e.g., A Coruña, Pontevedra), well above the national average.
• Regions with higher rainfall and fewer sunshine hours (e.g., Gipuzkoa, Asturias) had significantly higher TB rates, particularly extrapulmonary TB.
• Spatial regression analyses confirmed a strong link between reduced sunlight and higher TB incidence, reinforcing the potential role of vitamin D in TB susceptibility.
• TB cases peak seasonally in spring (May), about four months after winter’s lowest sunlight levels, suggesting an environmental influence on TB trends.
• These findings highlight the relevance of environmental and seasonal factors, particularly sunlight exposure, in modulating TB incidence and informing prevention strategies.

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3. Active Case Finding (ACF) and TB Control in High-Risk Groups

• ACF is effective for early TB detection, especially among migrants, the homeless, prisoners, and impoverished populations, where it outperforms passive case finding.
• ACF strategies include door-to-door screening, mobile clinics, and point-of-care tools like battery-operated GeneXpert systems (e.g., XACT), improving early detection and reducing transmission.
• Mobile clinics are more efficient and scalable than labor-intensive door-to-door approaches, offering quicker treatment initiation and better community reach.
• WHO recommends contact screening and latent TB infection (LTBI) screening for migrants when resources permit; integrating support services can help overcome barriers like legal status and social isolation.
• While ACF has clear benefits in high-risk groups, its effectiveness in the general population of developing countries remains limited, necessitating further research and tailored strategies.

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4. Health Education, Self-Management, and TB Treatment Adherence

• Health education significantly improves self-efficacy, treatment adherence, and disease knowledge in pulmonary TB patients, as shown in multiple studies (Jauhar 2019; Nuwa & Kiik 2021; Haskas 2023).
• Video-based and self-management education enhances adherence, health behaviors, perceived control, and nutritional management, reinforcing the need for patient-centered interventions.
• Knowledge is the dominant factor influencing adherence; interventions based on the health belief model and audiovisual tools have proven effective in improving compliance.
• Family and community support improves psychological well-being and coping, increasing the likelihood of treatment completion in TB patients.
• Self-management education is critical not only in TB but also for chronic diseases like diabetes and hypertension, fostering comprehensive care that includes medication adherence, physical activity, and transmission prevention.

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5. TB-Diabetes Mellitus (DM) Comorbidity: Endocrine-Immune Interactions and Treatment Implications

• TB and T2D comorbidity involves complex endocrine-immune disruptions; cytokines (IL-1, IL-6, TNF-α) trigger HPA and HPT axis activation but suppress the HPG axis, contributing to endocrine dysfunction.
• TB-T2D patients show hormonal imbalances (high cortisol, low DHEA/leptin), impairing immunity (reduced PRR/MHC expression, foam cell formation) and promoting Mycobacterium tuberculosis persistence.
• Hormonal modulators like glucocorticoids, leptin, DHEA, and GH influence lung immunity; experimental therapies targeting hormone receptors (e.g., α-MSH, GHRHR inhibitors) show potential.
• Cholesterol and lipid profiles affect TB risk and treatment outcomes; low cholesterol links to higher TB risk, while elevated triglycerides predict poor outcomes—cholesterol may aid immune defense by enhancing macrophage activity.
• The link between diabetes, BMI, and TB risk remains unclear, especially in Asian populations; distinguishing transient stress-induced hyperglycemia from clinical T2D during TB treatment is essential for accurate diagnosis and management.

Curated by Yoseph Leonardo Samodra

References:

1. Galán, M.D.M.D., Redondo-Bravo, L., Gómez-Barroso, D., Herrera, L., Amillategui, R., Gómez-Castellá, J. and Herrador, Z., 2024. The impact of meteorological factors on tuberculosis incidence in Spain: a spatiotemporal analysis. Epidemiology & Infection, 152, p.e58.
2. Guillén, S.M., et al., 2023. Tuberculosis in Spain: An opinion paper. Rev Esp Quimioter, 36(6), pp.562-583.
3. Pramono, J.S., Ridwan, A., Maria, I.L., Syam, A., Russeng, S.S. and Mumang, A.A., 2024. Active case finding for tuberculosis in migrants: a systematic review. Medical Archives, 78(1), p.60.
4. Esmail, A., Randall, P., Oelofse, S. et al. Comparison of two diagnostic intervention packages for community-based active case finding for tuberculosis: an open-label randomized controlled trial. Nat Med 29, 1009–1016 (2023).
5. Rochmah, A.F., Zahroh, C., Nadatien, I., Setiyowati, E., & Hidaayah, N. (2024). Does education influence self-efficacy in tuberculosis patients? A systematic review. Journal of Applied Nursing and Health, 6(1), 128–138.
6. Yamanaka, T., Castro, M.C., Ferrer, J.P., Solon, J.A., Cox, S.E., Laurence, Y.V. and Vassall, A., 2024. Health system costs of providing outpatient care for diabetes in people with TB in the Philippines. IJTLD open, 1(3), pp.124-129.
7. Webber, T., Ronacher, K., Conradie-Smit, M. and Kleynhans, L., 2022. Interplay between the immune and endocrine systems in the lung: implications for TB susceptibility. Frontiers in immunology, 13, p.829355.
8. Ngo, M.D.; Bartlett, S.; Ronacher, K. Diabetes-Associated Susceptibility to Tuberculosis: Contribution of Hyperglycemia vs. Dyslipidemia. Microorganisms 2021, 9, 2282.

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