Human metapneumovirus in children with acute lower respiratory infections: effects on clinical and disease severity.

backgroundHuman metapneumovirus (HMPV) is a common cause of acute lower respiratory tract infections (ALRIs), accounting for 6-40% of paediatric outpatient visits and hospitalisations. However, its clinical severity and epidemiological characteristics remain poorly understood.

methodsTo investigate the epidemiology and clinical features of HMPV infection, hospitalised children with ALRIs from 2023 to 2024 were screened for HMPV and ten other common respiratory pathogens using multiplex polymerase chain reaction. Demographic data, clinical presentations, diagnose, and outcomes were compared between children with moderate and severe diseases.

resultsThe annual detection rate of HMPV was 7.5%, with peak incidence observed in summer and autumn. Children under 5 Years of age accounted for 93.9% of HMPV-associated ALRIs. Among the 131 confirmed cases, 35.1% were classified as severe. Wheezing, dyspnoea and liver function abnormalities were more frequently associated with severe cases. In contrast, mild or normal radiographic findings were significantly more common among children with moderate diseases. Furthermore, children with severe disease exhibited a significantly higher percentage of neutrophils, elevated levels of creatine kinase MB isoenzyme (CK-MB), and lower serum creatinine levels. Most hospitalized children recovered or showed clinical improvement. However, two infants under one year of age in the severe group died; both had underlying conditions.

conclusionsHMPV infections were primarily observed in summer and autumn During 2023-2024. Our findings underscore the importance of early identification of severe and potentially fatal HMPV-associated ALRI in pediatric populations. Given the observed seasonal pattern and the risk of severe outcomes-particularly among children with underlying conditions-timely diagnosis and risk stratification are critical for guiding clinical management and informing targeted public health interventions.