Detection of multiple viral agents in nasopharyngeal specimens yielding respiratory syncytial virus (RSV). An assessment of diagnostic strategy and clinical significance.

A retrospective study of 6 years (1981-1987) experience with clinical specimens of pediatric patients submitted for identification of respiratory viruses was undertaken to determine the prevalence of multiple viral isolates and to assess the impact of dual infections on severity of clinical disease. Respiratory Syncytial Virus (RSV), the most frequently identified agent, was detected in cell culture and/or by immunofluorescence (IF) in 666 of 2,415 specimens examined. A second virus was isolated in cell cultures from 51 of the 666 specimens (7.6%). Cytomegalovirus, rhinoviruses, adenoviruses, influenza and parainfluenza viruses, echoviruses, vaccine strain polio viruses, and herpes simplex virus were identified with RSV. The diagnosis of a dual viral infection would have been missed in 37 of 51 instances (79%) had rapid diagnosis for RSV been employed without inoculation of cell cultures. Demographics and clinical presentations were similar in patients with dual infections or RSV alone. A case-control study comparing patients with dual isolates and patients with RSV alone to determine the effect of multiple viral infections on severity of disease revealed no significant difference. The combined use of rapid methods and isolation in culture provides more complete viral diagnosis and could have an impact on the choice of antiviral agents and the institution of appropriate infection control measures.