Acute viral respiratory infection in children under 5 years. Epidemiological study in two centers in Buenos Aires, Argentina

Introduction. Acute respiratory infections (ARI) are a major cause of hospitalization particularly at the extreme ages of life. Objectives. To determine the viral diagnosis in children <5 years old with ARI, seasonality, clinical and epidemiological characteristics. Population and methods. A cross-sectional, descriptive and multicenter study was performed. Respiratory samples from patients with ARI hospitalized or outpatients with <5 days of respiratory symptoms from June 2008 to May 2009 were studied for respiratory viruses. Clinical and demographic data were recorded. Results. A total of 347 patients were enrolled: 234 hospitalized and 112 outpatients. Hospitalized patients were younger compared with outpatients (8 vs. 19 months, p <0.001) and presented more frequently bronchiolitis (74% hospitalized vs. 24% outpatients) and pneumonia (14% hospitalized vs. 5% outpatients). Age was statistically associated with hospitalization (p= 0.01). Viral diagnosis was achieved in 81% hospitalized and 57% of outpatients. Rhinovirus was the most frequent followed by respiratory syncytial virus. The rest of respiratory viruses were observed with lower frequency. Viral circulation was observed throughout the whole year. The median length of stay was 3.5 days. Intensive care was required in 11% of hospitalized patients and 3% required mechanical ventilation. No deaths were recorded. Conclusions. The use of viral diagnostic techniques allowed the identification of an etiologic agent in most of the hospitalized patients and more than half of outpatients. The addition of RT-PCR for rhinovirus, allowed the identification of this etiologic agent. Viral circulation was observed throughout the whole year. Hospitalized patients presented bronchiolitis and pneumonia more frequently than outpatients.