RESUMEN
A survey was conducted in two pediatric intensive care units in hospitals in Porto Alegre, Brazil, in order to monitor the main respiratory viruses present in bronchiolitis and/or pneumonia and their involvement in the severity of viral respiratory infections. Viral respiratory infection prevalence was 38.7 percent. In bronchiolitis, respiratory syncytial virus (RSV) was detected in 36 percent of the cases. In pneumonia, the prevalence rates were similar for adenovirus (10.3 percent) and RSV (7.7 percent). There was a difference among the viruses detected in terms of frequency of clinical findings indicating greater severity. Frequency of crackles in patients with RSV (47.3 percent) showed a borderline significance (p = 0.055, Fisher's exact test) as compared to those with adenovirus (87.5 percent). The overall case fatality rate in this study was 2.7 percent, and adenovirus showed a significantly higher case fatality rate (25 percent) than RSV (2.8 percent) (p = 0.005). Injected antibiotics were used in 49 percent of the children with RSV and 60 percent of those with adenovirus. Adenovirus was not detected in any of the 33 children submitted to oxygen therapy.