Respiratory infections in low and middle-income countries.

Objectives: To investigate the epidemiology, aetiology, diagnostics and management of childhood pneumonia in low and middle income countries (LMICs).

Design: Review of published english literature from 2019 to February 2024.

Results: Lower respiratory tract infections (LRTIs) still result in significant mortality in children under 5 years of age in LMICs. Important studies have reported a change in the pathogenesis of LRTIs over the last 5 years with respiratory syncytial virus (RSV) resulting in a large burden of disease. SARS-CoV-2 had a significant direct and indirect impact in children in LMICs. Mycobacterium tuberculosis (MTB) remains a priority pathogen in all children. Nucleic acid amplification and rapid antigen tests have improved diagnostic accuracy for MTB and other bacterial pathogens. Point of care diagnostics may overcome some limitations, but there is a need for better cost-effective diagnostics. Access to shorter courses of TB treatment are now recommended for some children, but child friendly formulations are lacking. The role of chest X-ray in TB has been recognized and included in guidelines, and lung ultrasound to diagnose LRTI is showing promise as a lower cost and accessible option.

Conclusion: Advances in diagnostics and large multi-centre studies have provided increased understanding of the causative pathogens of LRTIs in LMICs. Increased access to preventive strategies such as vaccines, treatment modalities including antivirals, and addressing upstream factors such as poverty are essential if further declines in LRTIs in LMICs are to be realised.