Tuberculosis in Brunei Darussalam

The burden of tuberculosis-diabetes mellitus (TBDM) comorbidity in Brunei Darussalam has remained largely unexamined until now. This retrospective cohort study assessed all registered TB cases in the country from 2013 to 2018 to determine the prevalence of DM among TB patients and explore associated factors. Findings revealed that 33.9% of TB patients were also diagnosed with DM, with a majority already aware of their diabetic status prior to their TB diagnosis. The annual prevalence remained stable over the six-year period, highlighting a persistent co-epidemic that warrants attention. Most TB cases were male, Malay, and classified as smear-positive pulmonary TB, and the TBDM group showed a slightly higher rate of treatment success compared to non-DM TB patients.[1]

Significant associations were found between TBDM and several risk factors. Older age, smear-positive TB, hypertension or heart disease, and renal disease were all independently associated with increased odds of DM among TB patients. Interestingly, the presence of chronic obstructive pulmonary disease or asthma appeared to be a protective factor. Patients over 31 years of age had at least five times the odds of having DM compared to younger counterparts. Among those with DM, individuals with a known history of the disease prior to their TB diagnosis had higher mortality rates than those newly diagnosed, suggesting that the chronic burden of DM may worsen TB outcomes if not well-managed before TB onset.[1]

These findings underline the importance of integrating diabetes screening and management into national TB control strategies, in line with WHO’s collaborative framework. The high rate of previously known DM cases among TB patients supports the need for proactive chronic disease management and routine DM assessments in TB care. Given the increased mortality and comorbidity burden associated with TBDM, programmatic interventions should prioritize early detection, integrated care models, and tailored public health policies that address both diseases concurrently.[1]

Over an 18-year period (2001–2018), weekly PTB case data from Brunei-Muara were analyzed alongside daily climate measurements that were averaged weekly. A total of 1,967 PTB cases were reported, with smear-positive cases accounting for 71.8%. Climate variables examined included sunshine hours, rainfall, wind speed, temperature (minimum, mean, maximum), relative humidity (RH), and derived vapour pressure. Spearman’s correlation analysis revealed a weak but significant positive association between PTB and humidity-related variables, particularly mean RH, maximum RH, and vapour pressure. Temperature and humidity variables showed stronger intercorrelations, indicating potential interaction effects.[2]

The core finding of this study was a delayed but significant positive association between PTB incidence and minimum temperature. Notably, higher minimum temperatures (specifically 25.1°C, the 95th percentile) were associated with increased PTB risk, with effects becoming statistically significant from approximately 30 weeks onwards. The adjusted relative risk (RR) increased progressively at longer lags, reaching a peak RR of 1.38 at 52 weeks. This association persisted even when the analysis was restricted to smear-positive PTB cases, reaffirming the robustness of the observation.[2]

In addition to temperature, rainfall was found to be positively associated with smear-positive PTB cases, with significant risk increases seen from lag 42 weeks onward. Other variables, such as wind speed and sunshine hours, exhibited non-linear patterns across lag periods, though these were not statistically significant. Importantly, sensitivity analyses confirmed the direction of observed trends, and multicollinearity was minimal, enhancing confidence in the model’s validity.[2]

These findings suggest that in Brunei’s equatorial setting, climate factors — especially minimum temperature and rainfall — may influence TB transmission, though the mechanisms are likely indirect and delayed. For instance, increased temperature or rainfall might alter human behavior, crowding patterns, or host immunity in ways that facilitate TB spread weeks or months later. This highlights the complex, context-specific nature of TB transmission in tropical regions.[2]

References:

1. Omar, N., Wong, J., Thu, K., Alikhan, M.F. and Chaw, L., 2021. Prevalence and associated factors of diabetes mellitus among tuberculosis patients in Brunei Darussalam: a 6-year retrospective cohort study. International Journal of Infectious Diseases, 105, pp.267-273.
2. Chaw, L., Liew, S.Q. and Wong, J., 2022. Association between climate variables and pulmonary tuberculosis incidence in Brunei Darussalam. Scientific Reports, 12(1), p.8775.