INTRODUÇÃO: As infecções respiratórias agudas (IRAs) constituem importante causa de morbidade e mortalidade em crianças nos países em desenvolvimento. A etiologia viral dessas infecções nem sempre é conhecida no Brasil, e estudos sobre as IRAs virais em crianças com doenças de base (DBs) são escassos. OBJETIVO: Determinar a etiologia viral dessas infecções em menores de 5 anos assistidos no Instituto Fernandes Figueira da Fundação Oswaldo Cruz (IFF/FIOCRUZ), Rio de Janeiro. MÉTODOS: Foram analisadas 285 amostras de aspirado de nasofaringe, obtidas de 204 crianças com IRA, de maio de 2005 a junho de 2006. RESULTADOS: Por meio da imunofluorescência indireta (IFI), 90 amostras (31,6%) foram positivas: 21,4% vírus sincicial respiratório (VSR); 3,5% adenovírus (Ad); 3,1% parainfluenza (PF) 3; 2,5% influenza (Flu) A; 0,7% PF 1; 0,4% Flu B. Das 195 negativas, 156 foram testadas para metapneumovírus humano (MPVh), com 15 positivas (9,6 % das amostras testadas). CONCLUSÃO: A prevalência viral nos serviços de ambulatórios foi de 42,8% e nos hospitalizados foi de 30%. Das crianças, 83,3% possuíam uma ou mais DBs associadas às IRAs, resultando em longos períodos de internação. Algumas delas tiveram múltiplas internações e múltiplos diagnósticos clínicos de IRA no período estudado.

INTRODUCTION: Acute respiratory infections (ARIs) are an important cause of morbidity and mortality among children in developing countries. The viral etiology of such infections is not always known in Brazil. Furthermore, studies on viral ARIs in children with underlying diseases (UD) are scanty. OBJECTIVE: The objective of this study was to determine the viral etiology of these infections among children under 5 years of age treated at Instituto Fernandes Figueira/Fundação Oswaldo Cruz (IFF/FIOCRUZ), Rio de Janeiro. METHOD: Two hundred and eighty-five samples of nasopharyngeal aspirate, which had been obtained from 204 children with ARI from May/2005 to June/2006, were analyzed. RESULTS: Samples were tested through indirect immunofluorescence assay and 90 of them (31.6%) were positive for the following viral agents: respiratory syncytial virus (21.4%), adenovirus (3.5%), parainfluenza 3 (3.1%), influenza A (2.5%), parainfluenza 1 (0.7%), and influenza B (0.4%). One hundred and ninety-five samples were negative, from which 156 were tested for human metapneumovirus, and 15 of them (9.6%) were positive. CONCLUSION: The viral prevalence among outpatients was 42.8% and among inpatients it was 30%; 83.3% of the children were carriers of one or more UD associated with ARI, resulting in long-term admission to hospital. Some children had multiple admissions and multiple clinical diagnoses of ARI during the studied period.

Viral replication, histopathological and ultrastructural changes were observed for a period of nine days in the small intestine of suckling mice infected with a simian rotavirus (SA11). Samples taken from duodenum, jejunun and ileum were prepared for light microscopy, transmission and scanning electron microscopy analysis. Histopathologic effect could be detected within 8 hr post-infection, when only a few altered cells were observed. Damage was extensive after 16 hr post-infection, showing swollen enterocytes and reduced and irregularly oriented microvilli at intestinal villi tips. Virus particles were detected at 16 and 48 hr post-infection, budding from the viroplasm into the rough endoplasmic reticulum cisternae in ileum enterocytes. Clear evidence of viral replication, observed by electron microscopy was not described before in heterologous murine models. Regeneration of the intestinal villi began at the third day post-infection. Despite some differences observed in clinical symptoms and microscopic analysis of homologous and heterologous rotavirus infections, we concluded that mechanisms of heterologous rotavirus infection in mice follow similar patterns to those observed in the homologous models.