From the Guidelines
Yes, there is a test for Norovirus.
Testing Methods
- RT-PCR (Reverse Transcription-Polymerase Chain Reaction): This is the most commonly used method for norovirus detection, with high sensitivity and specificity 1.
- EIA (Enzyme Immunoassay): This method is also available, but its sensitivity and specificity are lower compared to RT-PCR, ranging from 36% to 80% and 47% to 100%, respectively 1.
Specimen Collection
- Whole stool specimens are preferred over rectal swabs for laboratory diagnosis of norovirus, as they contain a higher quantity of virus 1.
- Vomitus may also be collected and tested using molecular assays, but the sensitivity of these assays for vomitus is unknown 1.
Interpretation
- An outbreak of acute gastroenteritis is considered to be laboratory-confirmed as attributable to norovirus if stool or vomitus specimens from two or more ill persons are positive for norovirus by RT-PCR, EIA, or electron microscopy 1.
From the Research
Diagnostic Tests for Norovirus
There are several diagnostic tests available for norovirus, including:
- Electron microscopy 2
- Reverse transcription-polymerase chain reaction (RT-PCR) 2, 3
- Real-time RT-PCR 2, 3
- Enzyme immunoassay kits 2, 3
- Nucleic acid sequence-based amplification 2
- Immunochromatographic tests, such as RIDA® QUICK Norovirus 3, 4
Characteristics of Diagnostic Tests
The characteristics of these tests vary, with:
- Sensitivity ranging from 48.2% to 57.1% for immunochromatographic tests 3, 4
- Specificity ranging from 87.5% to 99.1% for immunochromatographic tests 3, 4
- Positive predictive values ranging from 93.3% to 91.2% for immunochromatographic tests 4
- Negative predictive values ranging from 91.2% for immunochromatographic tests 4
Limitations and Interpretations
The interpretation of test results should take into account the limitations of the different tests currently available 5 False positive and false negative results can occur, especially with immunochromatographic tests 3, 4 A negative result from a rapid test should be followed up by RT-PCR for confirmation 4