Viral etiologies of infant bronchiolitis, croup and upper respiratory illness during 4 consecutive years

Area of Science:

• Pediatric infectious diseases
• Virology
• Epidemiology

Background:

• Limited prospective data exists on viral causes and clinical features of infant bronchiolitis and upper respiratory illness (URI).
• Understanding these factors is crucial for effective diagnosis and management of common infant respiratory infections.

Purpose of the Study:

• To prospectively identify the viral etiology of acute URI and bronchiolitis in infants.
• To characterize the clinical presentation and severity of these illnesses.
• To explore demographic and seasonal variations in viral infections.

Main Methods:

• A prospective cohort study enrolled previously healthy term infants presenting with acute URI or bronchiolitis.
• Illness severity was assessed using an ordinal bronchiolitis severity score.
• Real-time reverse-transcriptase polymerase chain reaction (RT-PCR) was used for common respiratory virus identification.

Main Results:

• Respiratory syncytial virus (RSV) and human rhinovirus (HRV) were the most frequent viral pathogens identified.
• RSV was predominant in bronchiolitis (76%), while HRV was common in URI (46%) and croup (39%).
• Distinct seasonal, demographic, and clinical patterns were observed for individual viruses.

Conclusions:

• RSV and HRV are the leading causes of infant respiratory infections requiring unscheduled medical visits.
• Observed demographic differences suggest host and viral factors influence the clinical expression of these viral illnesses.
• These findings highlight the importance of considering specific viruses based on patient demographics and seasonality.