Abstract
BACKGROUND: Acute respiratory infections (ARIs) remain a leading cause of childhood morbidity and mortality in low-resource settings. This hospital-based observational study investigated the etiology, seasonal trends, and co-infections of respiratory pathogens using the multiplex polymerase chain reaction (PCR) panel among children under five from Eastern India. STUDY DESIGN: From January to December 2024, 209 samples (nasopharyngeal swabs/throat swabs or bronchoalveolar lavage) were collected from children under five who visited a tertiary healthcare center at Bhubaneswar, Odisha, India, with ARI/severe ARI (SARI). Multiplex PCR was used to identify the pathogens. All the data were recorded in a pre-designed case record form and analyzed using appropriate statistical tests. RESULT: Overall, 59.8% (125/209) tested positive for viral pathogens, predominantly human rhinovirus (HRV, 21.05%) and respiratory syncytial virus (RSV, 16.26%). Bacterial pathogens were detected in 45.45% (95/209), primarily Haemophilus influenzae (11%) and Klebsiella pneumoniae (7.65%). Viral co-infections occurred in 6.69% (14/209), with HRV-RSV being the most common, while bacterial co-infections (8.61%) frequently involved Streptococcus pneumoniae and H. influenzae. Seasonal peaks for viral infections occurred post-monsoon (October), whereas bacterial infections peaked during monsoon (September). ARI cases showed higher odds of bacterial etiology (OR 1.04, P = 0.87), whereas SARI cases showed higher odds of viral etiology (OR 0.65, P = 0.04). CONCLUSION: The findings underscore HRV and H. influenzae as dominant agents, highlighting the need for region-specific surveillance, improved diagnostics, and targeted vaccination strategies to mitigate ARI burden in children under five.