Viral etiology of lower respiratory tract infections in hospitalized children in Mexico

BACKGROUND: Respiratory viruses are the main cause of lower respiratory tract infections (LRTI) reported worldwide. The contribution of viral infections to respiratory infections in Mexico has not been fully determined. OBJECTIVE: To determine the contribution of viral infections in hospitalized children with LRTI. METHODS: Children younger than 15 years of age with the admission diagnosis of LRTI were eligible for this study. A nasal wash specimen for virus identification by direct immunofluorescent assay (DFA) was obtained as soon as possible after admission. Clinical and radiographic findings of children with positive and negative detection of viruses were compared. RESULTS: Of 285 subjects admitted to the hospital with LRTI, 265 (93%) had an appropriate specimen for DFA. A viral agent was detected in 125 (47.2%) specimens. Viruses that were identified included respiratory syncytial virus (107), influenza (9) and parainfluenza type 3 (9). Clinical and radiologic diagnoses included bronchiolitis (127), interstitial pneumonia (47) and pneumonia (91). Of the subjects included in the study, 71.3% were younger than 1 year of age. Children with a confirmed viral etiology for their LRTI were younger, had higher respiratory rates on admission and were more likely to present with bronchiolitis than subjects with a negative DFA result. CONCLUSIONS: Respiratory viruses are responsible for at least 47.2% of LRTI requiring hospitalization at our hospital. Respiratory syncytial virus was the most important respiratory agent identified.