Rapid diagnosis of human parainfluenza virus type 1 infection by quantitative reverse transcription-PCR-enzyme hybridization assay.

The detection and quantitation of human parainfluenza virus type 1 (HPIV-1) RNA in nasal wash specimens from 49 children with lower respiratory infections were performed by a reverse transcription-PCR-enzyme hybridization assay (RT-PCR-EHA). The HPIV-1 RT-PCR-EHA was then used to test 40 samples from asymptomatic children. Primers and probes were designed from regions within the HPIV-1 hemagglutinin-neuraminidase gene which are highly conserved among all known genotypes. HPIV-1 was detected in all nine children who were culture positive. Other common respiratory viruses (HPIV-2, -3, and -4, mumps virus, respiratory syncytial virus, and influenza virus) were not detected by the HPIV-1 assay. Forty symptomatic children were negative by culture, and four of these were positive by RT-PCR-EHA. All of the samples from asymptomatic children were negative by culture and RT-PCR-EHA. RT-PCR-EHA was 100% sensitive (95% confidence interval, 0.66 to 1.00) and 95% specific (95% confidence interval, 0.88 to 0.99) compared with culture. The four false-positive results (relative to the results of culture) were in children with lower respiratory infections compatible with HPIV-1 infection and suggest that RT-PCR-EHA may be more sensitive than culture. Our data indicate that HPIV-1 may be underdiagnosed by routine culturing methods. RT-PCR-EHA has been demonstrated to be an easy, rapid, sensitive, and specific test for diagnosing HPIV-1 infection and provides a methodology for the rapid detection of closely related respiratory viruses.