Comparison of immunofluorescence & culture for the diagnosis of respiratory syncytial virus infection.

In 809 infants and children with acute respiratory infection, HEp-2 cells were used for the isolation of respiratory syncytial virus (RSV) and an indirect immunofluorescence technique (IIF) was used for the detection of RSV antigen in the epithelial cells of nasopharyngeal secretions. While RSV was detected in culture in only 87 subjects, IIF was positive for viral antigen in 158 subjects. In children with bronchiolitis and in those with pneumonia 57 and 19 per cent respectively, had evidence of RSV infection by culture or IIF. The frequency of virus antigen detection by IIF was above 90 per cent irrespective of the duration of symptoms before specimen collection. The frequency of virus isolation in culture was 86 per cent in children with less than 2 days duration of symptoms and 42 to 69 per cent in those with duration of symptoms of 2 days or more. However, this difference was not statistically significant. In conclusion, the IIF test was not only rapid, but also more sensitive for the detection of RSV infection than culture.