Comparison of Direct Fluorescence Assay and Real-Time RT-PCR as Diagnostics for Respiratory Syncytial Virus in Young Children

Caroline F Shafik,Emad W Mohareb,Fouad G Youssef

doi:10.1155/2011/781919

Caroline F Shafik, Emad W Mohareb + Show 1 more

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https://doi.org/10.1155/2011/781919

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Abstract

Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract infections in children worldwide. Early detection of RSV is critical to initiate proper care. Two methods, the direct fluorescence assay (DFA) and the real-time reverse-transcription polymerase chain reaction (rt-RT-PCR), that are used for RSV detection were compared. A total of 451 nasopharyngeal aspirates from children 5 years of age or less were tested for RSV using both methods. The overall prevalence rate of the RSV among the children was 23.7% with a significantly higher prevalence among children under the age of 6 months of age when compared to other age groups. The sensitivity of DFA in comparison to rt-RT-PCR was highest (86%) during the first 3 days of symptoms onset and decreased gradually till it reached 65% after the first week. The specificity of DFA in comparison to rt-RT-PCR ranged between 99 and 100% irrespective of the date of collection. We concluded that, although the rt-RT-PCR is more sensitive for RSV detection, the DFA offers a reliable point-of-care alternative detection method especially during the first few days of illness.

Highlights

Respiratory syncytial virus (RSV) is a negative sense singlestranded RNA virus belonging to Pneumovirus genus, subfamily Pneumovirinae
Sensitivity of Direct Fluorescence assay (DFA) was calculated by dividing the number of samples positive for RSV by both DFA and rt-RT-PCR by the total number of samples positive by rtRT-PCR
Positive Predictive Value (PPV) of DFA was calculated by dividing the number of samples positive by both DFA and rt-RT-PCR by the total number of DFA positive samples. negative predictive value (NPV) was calculated by dividing the number of samples negative by both DFA and rt-RT-PCR by the total number of DFA negative samples

Summary

Introduction

Respiratory syncytial virus (RSV) is a negative sense singlestranded RNA virus belonging to Pneumovirus genus, subfamily Pneumovirinae. RSV is considered a major cause of severe lower respiratory tract infections in children less than two years of age worldwide [1]. Direct Fluorescence assay (DFA) is a conventional method that is frequently used in the clinical setting for the detection of respiratory viruses including RSV. Nucleic acid detection methods have proven to be more sensitive for RSV detection [3]. Developing countries, cannot afford to use nucleic acid detection methods within hospital laboratories due to high cost and lack of technical expertise. We compared the sensitivity and specificity of the DFA against real-time reverse transcriptase polymerase chain reaction (rt-RT-PCR) as a point-of-care method for RSV detection. Comparison was made between both assays in relation to the days after onset of symptoms

Materials and Methods

Results

Conclusion