Diagnosis of respiratory syncytial virus infection in children: comparison of viral antigen detection and serology.

Direct detection of viral antigen in nasopharyngeal secretion by radioimmunoassay was compared with serology by IgG antibody enzyme immunoassay for diagnostic efficacy in 77 children with clinically suspected respiratory syncytial virus (RSV) infections. Antigen detection gave a positive diagnosis in 26 of 33 (79%) children in whom RSV infection was diagnosed by any of the two methods. The diagnostic efficacy of antigen detection was dependent upon the interval after onset at which specimens were collected; 88% of specimens taken during the first 5 days and 50% of specimens taken 6-10 days after onset of illness were positive. It was also dependent on the age of the patients, the diagnostic efficacy being 88 and 76% in children under and over 6 months of age, respectively.