Two outbreaks of norovirus infections associated with the consumption  of imported frozen raspberries, Denmark, May-June 2005

Korsager, Birgitte; Hede, Susanne; Bøggild, Henrik; Böttiger, Blenda; Mølbak, Kåre

doi:10.2807/esw.10.25.02729-en

Cited by 29 publications

(24 citation statements)

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“…Thus, given the stability of cryoconserved NV, it must be assumed that NV remains infective under freezing conditions. The results of epidemiological studies corroborate this conclusion, since outbreaks of NV infection were associated with consumption of frozen raspberries (23,55,72). Thermal processes are used for production, preparation, and preservation of foods.…”

Section: Discussionsupporting

confidence: 76%

Effects of Technological Processes on the Tenacity and Inactivation of Norovirus Genogroup II in Experimentally Contaminated Foods

Mormann¹,

Dabisch²,

Becker³

2010

Appl Environ Microbiol

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Contaminated food is a significant vehicle for human norovirus transmission. The present study determined the effect of physicochemical treatments on the tenacity of infective human norovirus genogroup II in selected foods. Artificially contaminated produce was subjected to a number of processes used by the food industry for preservation and by the consumer for storage and preparation. Virus recovery was carried out by using ultrafiltration and was monitored by using bacteriophage MS2 as an internal process control. Norovirus was quantified by using monoplex one-step TaqMan real-time reverse transcription (RT)-PCR and an external standard curve based on recombinant RNA standards. An RNase pretreatment step was used to avoid false-positive PCR results caused by accessible RNA, which allowed detection of intact virus particles. Significant reductions in titers were obtained with heat treatments usually applied by consumers for food preparation (baking, cooking, roasting). Generally, processes used for preservation and storage, such as cooling, freezing, acidification (>pH 4.5), and moderate heat treatments (pasteurization), appear to be insufficient to inactivate norovirus within a food matrix or on the surface of food. Besides data for persistence in processed food, comparable data for individual matrix-specific protective effects, recovery rates, and inhibitory effects on the PCRs were obtained in this study. The established procedure might be used for other noncultivable enteric RNA viruses that are connected to food-borne diseases. The data obtained in this study may also help optimize the process for inactivation of norovirus in food by adjusting food processing technologies and may promote the development of risk assessment systems in order to improve consumer protection.Norovirus (NV) (formerly Norwalk-like virus) is a member of the family Caliciviridae and is a nonenveloped virus with a single-stranded RNA (ssRNA) genome. Genetically, the human noroviruses are subdivided into three distinct genogroups (genogroup I [GGI], GGII, and GGIV) and into at least 31 genetic clusters or genotypes (53). Noroviruses have emerged as the most common cause of food-borne outbreaks and sporadic cases of acute nonbacterial gastroenteritis worldwide (62,87).In addition to direct person-to-person infection, transmission via environmental contamination (70) and transmission via foods and drinking water (primary and secondary contamination) are known. Food can be contaminated by contact with sewage or sewage water before harvest; e.g., shellfish (3,52,58,60,81) and raspberries (33, 72) have been reported to be vehicles of NV infection. Food is often directly contaminated during production, storage, distribution, and preparation by infected persons (22); e.g., ill or asymptomatic food handlers have been identified as sources of virus contamination of fresh produce and ready-to-eat foods (25, 69). The percentage of cases that can be attributed to food-or waterborne transmission is estimated to be between 16% (56) and 57% (34). Hu...

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Section: Discussionsupporting

confidence: 76%

Effects of Technological Processes on the Tenacity and Inactivation of Norovirus Genogroup II in Experimentally Contaminated Foods

Mormann¹,

Dabisch²,

Becker³

2010

Appl Environ Microbiol

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“…Transmission of viruses associated with the consumption of contaminated bivalve shellfish, particularly, oysters which are eaten uncooked, is regularly reported (Koopmans and Duizer 2004;Widdowson et al 2005). Other foods, including raspberries (Cotterelle et al 2005;Le Guyader et al 2004;Gaulin et al 1999;Korsager et al 2005;Hedlund et al 2000;Falkenhorst et al 2005;Hjertqvist et al 2006;Fell et al 2007;Ponka et al 1999) and salads (Vivancos et al 2009), have caused outbreaks after being contaminated by polluted water or virus-infected food handlers. Polluted water, both drinking water and recreational water, have been shown to have transmitted viruses (Cannon et al 1991;Lawson et al 1991;Maunula et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Analytical Methods for Virus Detection in Water and Food

et al. 2010

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Potential ways to address the issues that relate to the techniques for analyzing food and environmental samples for the presence of enteric viruses are discussed. It is not the authors' remit to produce or recommend standard or reference methods but to address specific issues in the analytical procedures. Foods of primary importance are bivalve molluscs, particularly, oysters, clams, and mussels; salad crops such as lettuce, green onions and other greens; and soft fruits such as raspberries and strawberries. All types of water, not only drinking water but also recreational water (fresh, marine, and swimming pool), river water (irrigation water), raw and treated sewage are potential vehicles for virus transmission. Well over 100 different enteric viruses could be food or water contaminants; however, with few exceptions, most well-characterized foodborne or waterborne viral outbreaks are restricted to hepatitis A virus (HAV) and calicivirus, essentially norovirus (NoV). Target viruses for analytical methods include, in addition to NoV and HAV, hepatitis E virus (HEV), enteroviruses (e.g., poliovirus), adenovirus, rotavirus, astrovirus, and any other relevant virus likely to be transmitted by food or water. A survey of the currently available methods for detection of viruses in food and environmental matrices was conducted, gathering information on protocols for extraction of viruses from various matrices and on the various specific detection techniques for each virus type.

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“…In contrast to other gastroenteritis viruses, NoVs infect all age groups (3). The viruses are spread rapidly and can cause large outbreaks in a wide variety of settings, including health care facilities, restaurants, and schools (5,6,11,17,20,23,32). Since many countries do not have national NoV surveillance programs, the completeness and quality of reporting systems vary substantially.…”

mentioning

confidence: 99%

Multicenter Comparison of Two Norovirus ORF2-Based Genotyping Protocols

et al. 2009

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Point source norovirus outbreaks can be difficult to track due to high background levels of the virus in the environment and the limited strain variation in some genotyping regions. However, rapid and accurate source identification can limit the spread of a foodborne outbreak and reduce the number of cases. Harmonization of genotyping assays is critical for enabling the rapid exchange of sequence data nationally and internationally. Several regions of the genome have been proposed for this purpose, but no consensus has been reached. In the present study, two standardized genotyping protocols (region C and region D) were evaluated by nine laboratories in Canada and the United States, using a coded panel of 96 fecal specimens representing 22 different norovirus genotypes. Overall, region C typing had a success rate of 78% compared to 52% for region D; however, region D provides greater nucleotide sequence diversity for identifying new GII.4 variant strains. Significant differences in the genotyping success rate were observed among the nine participating laboratories (10% to 100%) and among the different genotypes (6% to 100%). For several genogroup II strains, reduced region D amplification correlated directly with mismatches between primer sequences and the template. Based on overall performance, we recommend the region C protocol for routine genotyping of noroviruses, while the region D protocol may be useful for identifying new GII.4 variants. Standardized genotyping protocols will enable rapid exchange of outbreak and sequence data through electronic norovirus surveillance networks.

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Two outbreaks of norovirus infections associated with the consumption of imported frozen raspberries, Denmark, May-June 2005

Abstract: On the weekend of 21-22 May, it was reported that 101 patients and 76 employees at the two Aalborg Hospitals

Cited by 29 publications

References 0 publications

Effects of Technological Processes on the Tenacity and Inactivation of Norovirus Genogroup II in Experimentally Contaminated Foods

Effects of Technological Processes on the Tenacity and Inactivation of Norovirus Genogroup II in Experimentally Contaminated Foods

Analytical Methods for Virus Detection in Water and Food

Multicenter Comparison of Two Norovirus ORF2-Based Genotyping Protocols

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