Respiratory syncytial virus infection. Rapid diagnosis in children by use of indirect immunofluorescence.

Specimens of 387 nasopharyngeal suction smears obtained from 354 children hospitalized with acute respiratory infections during an eight-month period were examined for the presence of respiratory syncytial (RS) virus by the indirect immunofluorescence antibody technique (IFAT) and by conventional tissue culture infectivity techniques. Respiratory syncytial virus was identified in nasopharyngeal suction smear specimens from 123 of these specimens (32%) with the use of both techniques. Of the specimens positive on tissue culture 92% were also positive for RS virus by IFAT. However, eight specimens positive for RS virus by tissue culture were negative by IFAT, although three of the specimens were technically unsuitable. Six percent of the specimens negative for RS virus by tissue culture were positive for RS virus antigen when tested by IFAT. Using IFAT, identification of RS virus could be accomplished within four to six hours, whereas isolation by tissue culture took an average period of ten days. These data suggest that IFAT is a reliable means for the rapid diagnosis of RS virus infection in infants and children.