An outbreak of norovirus infection linked to oyster consumption at a UK restaurant, February 2010

Baker, Kenneth F.; Morris, Jill; McCarthy, Noel D.; Saldaña, Luisa; Lowther, James; Collinson, Andrew; Young, Michael C.

doi:10.1093/pubmed/fdq089

Cited by 49 publications

(26 citation statements)

References 19 publications

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“…Enteric viruses, such as NoVs or hepatitis A, have been involved in gastroenteritis outbreaks associated with different food sources (Baker et al 2010;Maunula et al 2009;Grotto et al 2004;Ethelberg et al 2010), and consequently, the effect of standard and novel inactivation processes on food borne viruses needs to be assessed. The use of a surrogate virus is currently the most common approach.…”

Section: Discussionmentioning

confidence: 99%

Virus Genome Quantification Does not Predict Norovirus Infectivity After Application of Food Inactivation Processing Technologies

et al. 2011

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When determining the effect of food processing on the infectivity of any contaminating virus, it is necessary to distinguish unambiguously between infectious and noninfectious viruses present. However, this can be difficult in the particular case of noroviruses (NoVs) because no reliable cell culture model is available. The aim of this study was to assess the use of molecular methods-RT real-time PCR (RT-qPCR) and enzymatic treatment (ET) coupled to RT-qPCR-to quantify the infectivity of NoV after application of various inactivating food-processing technologies. RT-qPCR and ET-RT-qPCR gave significantly different (P \ 0.01) results concerning the reduction in viral genome counts by all inactivation procedures and conditions used, except for HHP treatment at 600 MPa for 5 min. These findings indicate that the ET prior to RT-qPCR has an effect on the estimation of the reduction of virus genome counts, and may eliminate genomes of affected virus particles. However, no correlation was found between the results obtained by ET-RT-qPCR and those obtained by cell culture. Therefore, the effect is presumably only partial, and not adequate to allow accurate estimation of virus inactivation. Consequently, our results indicate that the quantification of virus genomes by PCR, regardless of prior ET, is not adequate for establishing virus inactivation and/or infectivity. In addition, our results also illustrate that the general effect of virus inactivation is not directly correlated to effects on the integrity of virus genome and protein capsid. Presumably, inactivation by food processing is the consequence of effects on proteins involved in adhesion and invasion stages.

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Section: Discussionmentioning

confidence: 99%

Virus Genome Quantification Does not Predict Norovirus Infectivity After Application of Food Inactivation Processing Technologies

et al. 2011

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“…The contamination of an oyster with multiple NoV strains complicates the investigations further. When stool samples are analyzed, variability is observed as different individuals may be infected by different strains present in the consumed oyster (Baker et al, 2011;Le Guyader et al, 2008). The genetic susceptibility of exposed consumers is an important factor, and may explain some variations in consumer illness .…”

Section: Quantitative Data From Outbreaksmentioning

confidence: 99%

Scientific Opinion on Norovirus (NoV) in oysters: methods, limits and control options

Publication¹

2012

EFSA Journal

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NoV is highly infectious, and there is no threshold infectivity limit for NoV detected by PCR. The probability of becoming infected increases with the dose but depends also on the characteristics of the organism, the food matrix and the host factors. The relationship between the number of infectious virus particles and the number of virus genome copies detected by quantitative PCR is not a constant, and it is important to realise that the infectious risk associated with low level positive oysters as determined by real‐time PCR may be overestimated. Quantitative data on viral load from areas compliant with current EU legislative requirements (E. coli standards) during January‐March 2010 in 3 selected member states, show that a viral limit of 100, 200, 500, 1000 or 10.000 NoV PCR copies would result in 33.6‐88.9%, 24.4‐83.3%, 10.0‐72.2%, 7.7‐44.4% or 0‐11.1% of non‐compliant batches, respectively. Compliance with any of the above NoV limits would reduce the number of contaminated oysters placed on the market and therefore the risk for consumers to become infected. It is currently not possible to quantify the public health impact of different limits. Microbiological criteria for NoV in oysters are useful for validation and verification of HACCP‐based processes and procedures, and can also be used by competent authorities as an additional control to improve risk management in production areas, during processing and retail. The Panel recommended that risk managers should consider establishing an acceptable limit for NoV in oysters to be harvested and placed on the market. NoV testing of oysters (standardized CEN method) should be used to verify compliance with the acceptable NoV limit established. The most effective public health measure to control human NoV infection from oyster consumption is to produce oysters from areas which are not faecally contaminated, particularly given the ineffectiveness of current depuration and relaying procedures.

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“…Under European regulations (14), assessment of the sanitary quality of shellfish harvest areas relies on the use of the bacterial indicator organism Escherichia coli. However, E. coli has been shown to be an inadequate indicator of viral contamination (15), and numerous NoV outbreaks have been caused by shellfish compliant with the current regulations (16)(17)(18). Furthermore, a characteristic of shellfish-related outbreaks is the presence of multiple NoV GI and GII genotypes in the feces of infected patients (19,20), whereas outbreaks in closed or semiclosed settings are generally associated with a single GII genotype (3), most commonly GII.4 (21).…”

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confidence: 99%

Norovirus Genotypes Present in Oysters and in Effluent from a Wastewater Treatment Plant during the Seasonal Peak of Infections in Ireland in 2010

Rajko-Nenow

Waters

Keaveney

et al. 2013

Appl Environ Microbiol

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We determined norovirus (NoV) concentrations in effluent from a wastewater treatment plant and in oysters during the peak period of laboratory-confirmed cases of NoV infection in Ireland in 2010 (January to March). Weekly samples of influent, secondary treated effluent, and oysters were analyzed using real-time quantitative reverse transcription-PCR for NoV genogroup I (GI) and genogroup II (GII). The mean concentration of NoV GII (5.87 × 104genome copies 100 ml−1) in influent wastewater was significantly higher than the mean concentration of NoV GI (1.40 × 104genome copies 100 ml−1). The highest concentration of NoV GII (2.20 × 105genome copies 100 ml−1) was detected in influent wastewater during week 6. Over the study period, a total of 931 laboratory-confirmed cases of NoV GII infection were recorded, with the peak (n= 171) occurring in week 7. In comparison, 16 cases of NoV GI-associated illness were reported during the study period. In addition, the NoV capsid N/S domain was molecularly characterized for selected samples. Multiple genotypes of NoV GI (GI.1, GI.4, GI.5, GI.6, and GI.7) and GII (GII.3, GII.4, GII.6, GII.7, GII.12, GII.13, and GII.17), as well as 4 putative recombinant strains, were detected in the environmental samples. The NoV GII.4 variant 2010 was detected in wastewater and oyster samples and was the dominant strain detected in NoV outbreaks at that time. This study demonstrates the diversity of NoV genotypes present in wastewater during a period of high rates of NoV infection in the community and highlights the potential for the environmental spread of multiple NoV genotypes.

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An outbreak of norovirus infection linked to oyster consumption at a UK restaurant, February 2010

Cited by 49 publications

References 19 publications

Virus Genome Quantification Does not Predict Norovirus Infectivity After Application of Food Inactivation Processing Technologies

Virus Genome Quantification Does not Predict Norovirus Infectivity After Application of Food Inactivation Processing Technologies

Scientific Opinion on Norovirus (NoV) in oysters: methods, limits and control options

Norovirus Genotypes Present in Oysters and in Effluent from a Wastewater Treatment Plant during the Seasonal Peak of Infections in Ireland in 2010

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