BACKGROUND: In 2006, bronchiolitis due to adenovirus nosocomial infections resulted in the closure of a pediatric department in northern Portugal. OBJECTIVES: To determine the etiology of bronchiolitis in northern Portugal. STUDY DESIGN: It was a prospective multicenter study on the etiology of bronchiolitis during the respiratory syncytial virus (RSV) season (November-April). Children < or = 24 months of age a...