Laboratory Testing

Several different types of laboratory tests are available for diagnosis of RSV infection. Rapid diagnostic assays performed on respiratory specimens are available commercially. Most clinical laboratories currently utilize antigen detection tests, and many supplement antigen testing with cell culture. Compared with culture, the sensitivity of antigen detection tests generally ranges from 80% to 90%. Antigen detection tests and culture are generally reliable in young children but less useful in older children and adults. Because of its thermolability, the sensitivity of RSV isolation in cell culture from respiratory secretions can vary among laboratories. Experienced laboratorians should be consulted for optimal results.

RT-PCR assays are now commercially available for RSV. The sensitivity of these assays often exceeds the sensitivity of virus isolation and antigen detections methods. Use of highly sensitive RT-PCR assays should be considered, particularly when testing older children and adults because they may have low viral loads in their respiratory specimens.

Serologic tests are less frequently used for routine diagnosis. Although useful for seroprevalence and epidemiologic studies, a diagnosis using paired acute- and convalescent-phase sera to demonstrate a significant rise in antibody titer to RSV cannot be made in time to guide patient care.