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Guideline for the Prevention and Control of Norovirus Gastroenteritis Outbreaks in Healthcare Settings, 2011

Q2: What are the best methods to identify a norovirus outbreak in a healthcare setting?

Diagnostic methods – Food specimens

PCR

Author, Yr (Ref) Study Design Quality Study Objective Population and Setting N Results Comments Ref ID_Data extracted by
Tian, P; 2006 145

Diagnostic Study

2
To develop a sensitive RT – Immuno PCR method for detecting norovirus capsid protein in food samples

Food samples contaminated with norovirus. Study was conducted in the US.

N/A

Detection limit of RT-Immuno PCR compared with ELISA and conventional RT-PCR
Viral RNA could be detected in samples diluted 1000 fold when compared with ELISA and 10-100 fold when compared with RT-PCR using fecal and food samples

Power and sample size not reported 4285_RA

Diagnostic methods – Water specimens

PCR

Author, Yr (Ref) Study Design Quality Study Objective Population and Setting N Results Comments Ref ID_Data extracted by
Wolf, S; 2007 134

Diagnostic study

2,3
To evaluate a multiplex real-time RT-PCR that distinguishes between norovirus genogroups I, II, and III and targets the junction between open reading frames 1 and 2 compared to Kageyama real time RT-PCR.              

Real time RT-PCR assays evaluated against 45 RNA samples collected from 2001-2006 known to be positive for norovirus including:
34 human stool samples from New Zealand
6 raw and 3 treated sewage samples
Single samples of contaminated drinking water and source water.

28 stool samples collected from asymptomatic cattle in May 2006 from farms in New Zealand.

Positive results
Multiplex real time RT-PCR positive for norovirus GI/1, GI/2, GI/3, GI/4, GI/5, GI/6, G1/7, GII/8, GII/10, GII/12, and GII/17 in different matrices (stool samples, treated and raw sewage, source water, and treated drinking water).

Agreement between the multiplex real time RT-PCR vs. Kageyama real time RT-PCR
All samples positive by Kageyama RT-PCR also positive by multiplex RT-PCR.
norovirus GI – 2/25 (8%) negative by Kageyama RT-PCR positive by multiplex RT-PCR.
norovirus GII –  3/17 (18%) negative by Kageyama RT-PCR positive by multiplex RT-PCR.

Cycle threshold (CT) values
In 16/20 norovirus GI samples and 26/28 norovirus GII samples positive by both assays, CT values for the multiplex assay were on average -2.4 CT U lower than for the Kageyama assay.

Remaining 6 samples had higher CT  values using the multiplex assay:
3/3 GI/3 specimens, on average +3.9 CT  U
1/1 GI/7 specimen, +3.5 CT U
1/1 GII/1 specimen, +3.3 CT U
1/1 GII/12, +1.4 CT U 

Level of detection
Multiplex real-time RT-PCR detects <10 copies/reaction of norovirus
GI/1, GII/3, and GIII/1 N/A. Calculated efficiency values of the assay were 0.93, 0.90, and 1.04 based on the slopes of the standard curves of 3.59, 3.60, and 3.23.

Kageyama real time RT-PCR compared to the multiplex real time RT-PCR.

A new bovine NLV, Bo/NLV/Norsewood/2006/NZL was identified using multiple real-time RT-PCR.

068_IL
Trujillo, A; 2006 18

Diagnostic study

2
To compare the test characteristics of Taqman RT-PCR with conventional RT-PCR for th edetection of GI, GII and GIV strains

Stool specimens from sporadic cases and outbreaks of gastroenteritis. Water samples from outbreaks of gastroenteritis in the US.

92 stool samples and 33 water samples

Test characteristics of Taqman RT-PCR vs. conventional RT-PCR
Stool specimens
TP – 65
TN – 27
FP – 0
FN – 0

By means of serially diluted norovirus RNA transcripts, a potential detection limit of < 10 transcript copies per reaction mixture was observed with the GII assay and a potential detection limit of < 10 transcript copies per reaction mixture was observed with the GI assay.

Water specimens
8/33 specimens were found to be positive. No test characteristics were reported

Power and sample size not reported 4225_RA

Concentration method

Author, Yr (Ref) Study Design Quality Study Objective Population and Setting N Results Comments Ref ID_Data extracted by
Beuret, C; 2003 146

Diagnostic study

None
To test a method for concentration of enteric viruses from water, whereby viruses are directly lysed after filtration on a negatively charged membrane. This method does not have the rinsing, elution, centrifugation and flocculation steps used in older protocols.

Water samples. Study was conducted in Switzerland.

Not reported

Detection limit
A sensitivity of a 106 fold dilution could be detected for norovirus which compared favorably to the older protocol

Power and sample size not reported 5853_RA

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