Prevalence and factors associated with tuberculosis among casual labourers employed in selected road construction projects in Central Uganda

Abstract

Introduction: Workers with occupational exposure to respirable silica dust are known to be at a high risk of developing tuberculosis (TB), especially in the lungs (pulmonary tuberculosis). However, there have been no studies to estimate the burden of TB among casual labourers who are also silica dust exposed workers and work in close proximity with each other hence the increased risk of occupational transmission. Objective: Determining the prevalence of TB and its associated factors among casual labourers employed in selected road construction projects in Central Uganda. Methods: The study enrolled 297 participants by consecutive sampling into a cross-sectional study that was carried out at the main campsites of each of the selected road construction projects (RCPs). Proportionate sampling was used to obtain a representative sample from each of the selected RCPs. Symptom screening, chest x-ray and GeneXpert in addition to a questionnaire were the methods used in data collection. Data were then entered into epi data and exported to Stata for analysis. Logistic regression adjusted for clustering through the survey analysis window was used both at bivariate and multivariate analyses to obtain crude and adjusted effect estimates respectively. Results: Most participants were males (n=284, 95.6%), median age was 29 years [IQR:25,33] and BMI of 22.6kg/m3 [IQR:21.1, 24.4]. The prevalence of TB among casual labourers was 2.0% (95% CI: 1.4,2.9) all of whom were males. BCG scar was the only factor associated with TB [aOR=5.326, P=0.045]. Conclusion: There is a high prevalence of TB among casual labourers employed in road construction projects in Central Uganda. For every 1,000 casual labourers involved in road works, 20 have TB, this statistic is 10 times higher than the national TB prevalence of approximately 3 TB cases for every 1,000 persons as reported in the report on Uganda’s national TB prevalence survey 2014/2015. Routine screening in all road construction sites is recommended to optimize active TB case finding and targeted vaccination among HIV-negative adults below the age of 35 years could be adopted to boost immunity of the casual labourers against TB.