Seasonal Variation in Respiratory Pathogen Detection and Clinical Characteristics Among Hospitalized Children With Acute Respiratory Illness in North India

Abstract

Background: Acute community-acquired respiratory infections (ACARI) continue to be a major contributor to pediatric hospitalizations globally and are highly concentrated in South Asia. Seasonal variation in weather conditions like temperature, humidity and monsoon activity has a strong influence on the circulation of respiratory virus and bacteria however there is limited region-specific data regarding the relation between seasonality, detection of pathogens and clinical presentation from Western Uttar Pradesh.

Objective: To study the seasonal variation in the detection of respiratory pathogens in children hospitalized with acute respiratory illness (ARI) from North India and to characterize clinical phenotype of pathogen detection.

Methods: This retrospective observational analytical study analysed prospectively collected hospital surveillance data from 210 hospitalized children aged 0–14 years with acute respiratory illness who underwent respiratory pathogen testing between 10 May 2024 and 9 February 2026, stratified by four predefined seasons (winter, pre-monsoon, monsoon, post-monsoon). Categorical variables were compared using the chi-square or Fisher's exact test, and continuous variables using the Mann–Whitney U test.

Results: Among the 210 samples analyzed, 76 (36.19%) tested positive for at least one pathogen. Specifically, a single pathogen was identified 38 cases (18%) involving only viral infections and 20 cases (9.52%) involving only bacterial infections. Mixed infections were observed in 18 cases (8.57%), while 134 samples (63.80%) were negative for pathogens.

Detection was highest in winter (54.1%) and lowest in pre-monsoon (23.9%; p=0.002), significant for virus-only detection (p=0.039) but not bacteria-only or mixed detection. RSV (31.57% of virus-positive children) was the commonest virus and, like most others, peaked in winter. Age did not differ significantly between pathogen-positive and pathogen-negative children (48.4 vs 51.1 months; p=0.466), whereas virus-positive children were significantly younger than virus-negative children (37.1 vs 54.9 months; p=0.009). Pathogen-positive and virus-positive children had higher rates of fever, shortness of breath, cough, expectoration, and rhinorrhea and longer illness duration (all p<0.05).

Conclusion: Respiratory pathogen detection showed significant winter predominance, and pathogen-positive and virus-positive children showed a more symptomatic clinical phenotype than pathogen-negative children.