Evaluation of four methods for the diagnosis of respiratory syncytial virus infection in older adults.

OBJECTIVE

To evaluate four methods of rapid diagnosis of respiratory syncytial virus (RSV) infection in older adults and to compare sensitivities with serologic analysis.

DESIGN

Prospective comparative analysis.

SETTING

Two adult daycenters.

PATIENTS

Frail older persons attending the daycenter who developed signs or symptoms of acute respiratory illness between the months of December and February.

MEASUREMENTS

Viral cultures performed by standard technique and bedside inoculation: antigen detection by indirect immunofluorescence assay (IFA) and Directigen enzyme immunoassay (EIA) on nasal brush samples; serologic analysis of acute and convalescent sera using EIA.

RESULTS

RSV infection was documented by serology in 11 of 54 (20%) subjects during the study period. Bedside viral cultures were the most sensitive assay and were positive in 6/9 infections. Standard viral culture detected 5/11 cases. Both methods of rapid antigen detection were found to be insensitive, with 1/11 detected by IFA and 0/11 detected by EIA.

CONCLUSION

Rapid antigen tests for the diagnosis of RSV in older persons should be used with caution.