Incidence, viral etiology, and risk factors of wheezing in children under two years of age: findings from a low-income urban community in Dhaka, Bangladesh.

BACKGROUND: The burden of early childhood wheezing in Bangladesh remains poorly characterised, despite infants’ exposure to viral pathogens and substantial particulate pollution. We conducted a longitudinal birth cohort study to estimate incidence, describe viral detections around episodes, and identify major risk factors of wheezing in children under two years of age. METHOD: We enrolled 447 newborns between May 2015 and March 2016 and followed them through 2022. In this study, we restricted the analysis to follow-ups conducted during the first two years of life through twice-weekly household surveillance. Physicians confirmed wheezing episodes, and nasopharyngeal wash samples collected during episodes were tested by rRT-PCR for major respiratory viruses, including rhinovirus (RV), respiratory syncytial virus (RSV), human metapneumovirus (hMPV), influenza virus, human parainfluenza virus (HPIV), and adenovirus. Incidence rates were calculated using Poisson-based methods with 95% confidence intervals, and multivariable Cox proportional hazards regression models were used to estimate adjusted hazard ratios (aHRs) to identify risk factors for wheezing. RESULTS: A total of 276 wheezing episodes were identified among 163 children. The incidence of wheezing was 35 episodes/100 child-years (95% CI: 31–40). Respiratory viruses were detected in 74.6% of wheezing episodes, yielding a viral wheezing incidence of 26 episodes/100 child-years (95% CI: 23–30). RV (35%) and RSV (22%) were the most commonly detected pathogens. Male sex (aHR: 1.48, 95% CI: 1.08–2.03), greater daily hours of PM2.5 concentrations above 50 µg/m3 (aHR: 1.05, 95% CI: 1.02–1.10), kerosene stove use (aHR: 3.23, 95% CI: 2.33–4.45), and wheezing episodes after intervals preceded by a prior ARI (aHR: 1.41, 95% CI: 1.09–1.83) were associated with an increased hazard of wheezing among the children. CONCLUSION: Early childhood wheezing was common, and the majority of these episodes were caused by viral pathogens in this high-density setting. Elevated particulate exposure and kerosene stove use further increased the risk. Interventions that reduce household particulate exposure and improve early wheeze management may help lower respiratory morbidity in similar environments.