Rapid diagnosis of parainfluenza virus infection in children.

The indirect immunofluorescent-antibody (IFA) assay for detection of parainfluenza virus antigen was performed on samples of nasopharyngeal secretions obtained from infants and children with various respiratory illnesses to determine the usefulness of the IFA assay for rapid diagnosis of parainfluenza virus infection. Ninety-four samples of nasopharyngeal secretions were obtained from 78 children during a community outbreak of parainfluenza virus infection. Application of the IFA assay revealed the presence of parainfluenza antigen in 67 of the 94 samples. When these same specimens were inoculated into tissue culture, the presence of parainfluenza virus was confirmed in 62 (93%) of the 67 IFA-positive specimens by hemadsorption on tissue culture monolayers (31 cases), presence of parainfluenza hemagglutinin in infected tissue culture fluids (23 cases), or by other methods (8 cases). Only four IFA-negative specimens were subsequently shown to be positive for parainfluenza virus by tissue culture infectivity. The IFA assay provided a more rapid and more accurate method for diagnosis of parainfluenza infection in children than did routine tissue culture methods employed currently.