RESUMEN
OBJECTIVE: Viral infection is the major cause of respiratory tract pathology affecting individuals of all ages, especially children and immunocompromised patients. There is a paucity of data on etiological and epidemiological infection caused by virus, in Southern Brazil. The aim of this study was to evaluate the seasonality, and the incidence of the viruses involved in respiratory infections in Curitiba, South Brazil. METHODS: Two hundred seventy-three nasopharyngeal aspirates (NPA) from primary care health units and 1348 NPA or bronchoalveolar lavages from a tertiary-care teaching hospital were studied. Viruses were identified by indirect immunofluorescence and cellular culture. RESULTS: Thirty percent of tested samples scored positive for the presence of virions. The percentages of infection for each virus from outpatients and hospitalized, respectively, were 3.3, 19.3 for respiratory syncytial virus; 13.9, 3.5 for influenza A, 3.0, 1.7 for influenza B; 3.3, 5.6 for parainfluenza virus and 2.2, 0.8 for adenovirus. A higher incidence of positive results was found during the winter season, thus showing a pattern of seasonality. CONCLUSION: Viral agents are one of the main etiologies of respiratory tract pathology in the population studied.