RESUMO
PURPOSE: Causes of acute lower respiratory tract infections (ALRI) in children are diverse. But virus is the most common cause of ALRI, so it is important to understand the etiology and epidemiology of ALRI. This study was performed to investigate the etiologic organisms, age distribution, clinical manifestations and seasonal occurrence of ALRI in hospitalized children. METHODS: We confirmed viral etiologies using nasopharyngeal aspirates in 377 patients of the ages of 15 years or younger who were hospitalized for ALRI from March, 1996 to February, 1999 at Samsung Seoul Hospital, Seoul, Korea. Viral agents were detected by virus isolation and antigen detection by indirect immunofluorescent staining. RESULTS: The viral pathogens identified were influenza A (22.2%), influenza B (9.0 %), adenovirus (21.2%), parainfluenza virus type 1 (8.8%), type 2 (3.4%), type 3 (15.1%) and respiratory syncytial virus (RSV) (20.2%). The occurrence of ALRIs was high under 2 year old. The clinical patterns of viral ALRI include pneumonia (49.9%), croup (20.2%), bronchiolitis (22.0%), tracheobronchitis (8.0%). The specific viruses are frequently associated with specific clinical syndrome of ALRI. The respiratory agents and associated syndromes frequently have characteristic seasonal patterns. CONCLUSION: This study will help us to estimate the etiologic agents of ALRI, and to avoid inappropriate antibiotic therapy. An annual nationwide survey is necessary to understand the viral epidemiology associated with respiratory illness.