Isolation and identification of viral agents in Argentinian children with acute lower respiratory tract infection.

From a total population of 1,002 children with acute lower respiratory infection (ALRI), identification of virus was achieved in 304 cases. In this survey, 1,000 nasopharyngeal aspirate and 13 lung tissue samples were tested in four cell lines (HEp-2, MRC-5, MDCK, and LLC-MK2) and by indirect immunofluorescence (IIF), while 242 paired sera were studied by complement fixation. Respiratory syncytial virus (RSV) was the most frequently detected agent (n = 183), followed by adenovirus (n = 28), parainfluenza (n = 5) and 3 (n = 16) viruses, and influenza A (n = 10) and B (n = 4) viruses. The sensitivity and specificity of IIF identification vs. isolation in cell culture were high for RSV (91.5% and 94.9%, respectively). However, IIF proved poorly sensitive for detection of adenovirus (sensitivity, 23.8%; specificity, 100%). The complement-fixation test proved the least effective, with a sensitivity of only 41.5%. Therefore, on the basis of our experience, it appears that the yield for positive diagnosis of virus is increased if both isolation in multiple cell lines and identification by means of IIF are used. Our survey provides for the first time reliable data on the viral etiology of ALRI in Argentina, as determined by three different methods.