A review of known and hypothetical transmission routes for noroviruses.

Department of Infectious and Parasitic diseases, Virology and Viral diseases, Faculty of Veterinary Medicine, University of Liège, Boulevard du Colonster 20, 4000, Liège, Belgium.
Food and Environmental Virology (Impact Factor: 2.51). 12/2012; 4(4):131-52. DOI: 10.1007/s12560-012-9091-z
Source: PubMed

ABSTRACT Human noroviruses (NoVs) are considered a worldwide leading cause of acute non-bacterial gastroenteritis. Due to a combination of prolonged shedding of high virus levels in feces, virus particle shedding during asymptomatic infections, and a high environmental persistence, NoVs are easily transmitted pathogens. Norovirus (NoV) outbreaks have often been reported and tend to affect a lot of people. NoV is spread via feces and vomit, but this NoV spread can occur through several transmission routes. While person-to-person transmission is without a doubt the dominant transmission route, human infective NoV outbreaks are often initiated by contaminated food or water. Zoonotic transmission of NoV has been investigated, but has thus far not been demonstrated. The presented review aims to give an overview of these NoV transmission routes. Regarding NoV person-to-person transmission, the NoV GII.4 genotype is discussed in the current review as it has been very successful for several decades but reasons for its success have only recently been suggested. Both pre-harvest and post-harvest contamination of food products can lead to NoV food borne illness. Pre-harvest contamination of food products mainly occurs via contact with polluted irrigation water in case of fresh produce or with contaminated harvesting water in case of bivalve molluscan shellfish. On the other hand, an infected food handler is considered as a major cause of post-harvest contamination of food products. Both transmission routes are reviewed by a summary of described NoV food borne outbreaks between 2000 and 2010. A third NoV transmission route occurs via water and the spread of NoV via river water, ground water, and surface water is reviewed. Finally, although zoonotic transmission remains hypothetical, a summary on the bovine and porcine NoV presence observed in animals is given and the presence of human infective NoV in animals is discussed.

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    ABSTRACT: The aim is to describe the epidemiological and laboratory investigation of a nosocomial outbreak of gastroenteritis and the effectiveness of control measures. In April 2011, an outbreak of gastroenteritis occurred in patients and personnel of the Orthopedic Department of Tzaneio General Hospital, Piraeus, Greece. The hospital infection control committee implemented a series of interventions for the containment of the outbreak. In particular, cases were defined as patients, visitors or hospital personnel with symptoms of vomiting and/or diarrhoea. Clinical and epidemiological information was collected from cases and from all patients hospitalized in the respective department. Investigation for similar cases was made to other hospital departments. Stool samples were submitted to the microbiological laboratory for routine culture, Clostridium difficile toxin assay, and detection of viral antigens. A total of 21 cases were identified; 10 were inpatients, 3 were visitors, and 8 were hospital personnel. All cases had diarrhoea, 6 had vomiting and 1 had fever. Symptoms lasted for 1-3 days and were generally mild. A common food- or water-borne source was not identified. Bacterial stool cultures yielded no enteric pathogen. The antigen immunoassays were positive for norovirus and the diagnosis was confirmed with reverse transcriptase RT-PCR. Instructions for strict hand hygiene and contact precautions were given. Hospital surfaces in the vicinity of the affected patients were cleaned with sodium hypochlorite solution and the rooms were aerated. Visits to the patients were discouraged. The outbreak lasted 10 days with no cases to occur thereafter. All affected staff members were asked to refrain from work until symptom resolution. In conclusion, the reported norovirus outbreak was probably introduced to a hospital department from the community. The prompt response to the outbreak prevented the spread to other hospital departments. Σκοπός της μελέτης ήταν η αναφορά της επιδημιολογικής και εργαστηριακής διερεύνησης συρροής κρουσμάτων γαστρεντερίτιδας στην Ορθοπεδική Κλινική του Γ.Ν.Π. «Τζάνειο», τον Απρίλιο του 2011, καθώς και της αποτελεσματικότητας των μέτρων ελέγχου. Με την παρέμβαση της Επιτροπής Νοσοκομειακών Λοιμώξεων ελήφθησαν άμεσα μέτρα περιορισμού της επιδημίας. Συγκεκριμένα, μελετήθηκαν όλες οι περιπτώσεις ασθενών, συνοδών και προσωπικού με συμπτώματα εμέτου και/ή διάρροιας. Συλλέχθηκαν επιδημιολογικές και κλινικές πληροφορίες από όλους τους νοσηλευόμενους στην κλινική κατά το συγκεκριμένο χρονικό διάστημα και από το προσωπικό. Διερευνήθηκε η ύπαρξη παρόμοιων περιστατικών στα υπόλοιπα νοσηλευτικά τμήματα. Εστάλησαν δείγματα κοπράνων για καλλιέργεια, πραγματοποιήθηκε αναζήτηση ιικών αντιγόνων και τοξίνης Clostridium difficile. Συνολικά προσβλήθηκαν 21 άτομα (10 ασθενείς, 8 μέλη του προσωπικού και 3 συνοδοί ασθενών). Όλοι οι προσβληθέντες εμφάνισαν διαρροϊκές κενώσεις, 6 ανέφεραν και εμέτους, ενώ ένας ασθενής παρουσίασε πυρετό. Η διάρκεια των συμπτωμάτων ήταν 1-3 ημέρες και η βαρύτητα ήταν ήπια. Δεν διαπιστώθηκε προέλευση της επιδημίας από κατανάλωση μολυσμένου τροφίμου ή νερού. Οι καλλιέργειες κοπράνων για εντεροπαθογόνα βακτήρια ήταν αρνητικές. Η αναζήτηση των ιικών αντιγόνων και η μοριακή επιβεβαίωση με RT-PCR ανέδειξαν ως αιτιολογικό παράγοντα τον Norovirus. Έγιναν συστάσεις για αυστηρή εφαρμογή της υγιεινής των χεριών και των προφυλάξεων επαφής. Πραγματοποιήθηκε επιμελής καθαρισμός όλων των επιφανειών που βρίσκονταν στο χώρο των προσβληθέντων με διάλυμα υποχλωριώδους νατρίου και καλός αερισμός των θαλάμων. Περιορίστηκε το επισκεπτήριο και τα προσβεβλημένα άτομα του προσωπικού απείχαν από την εργασία τους έως την πλήρη αποδρομή των συμπτωμάτων. H επιδημία διήρκεσε 10 μέρες και έκτοτε δεν αναφέρθηκαν νέα περιστατικά. Η νοσοκομειακή διασπορά του norovirus πιθανολογείται ότι οφείλεται σε εισαγωγή του ιού από ταυτόχρονη επιδημία στην κοινότητα. Η επιδημιολογική επιτήρηση συνέβαλλε στον άμεσο περιορισμό της επιδημίας.
    Acta Microbiologica Hellenica 07/2013; 58(3):7-11.
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    ABSTRACT: Noroviruses (NoVs) are genetically diverse, with genogroup II-and within it-genotype 4 (GII.4) being the most prevalent cause of acute gastroenteritis worldwide. The aim of this study was to characterize genogroup II NoV causing acute gastroenteritis in the Basque Country (northern Spain) from 2009-2012.
    PLoS ONE 06/2014; 9(6):e98875. · 3.53 Impact Factor
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    ABSTRACT: Noroviruses (NoVs) are a leading cause of epidemic and sporadic acute gastroenteritis worldwide. However, the genetic diversity and geographical distribution of NoV isolates from China have not been well described thus far. In this study, all NoV sequences obtained in China from 1999 to 2011 (n = 983), both partial and complete genomes, were downloaded from GenBank. Genotyping and phylogenetic and recombination analyses were performed in order to gain a better understanding of the distribution and genetic diversity of NoVs in China. The results indicated that approximately 90% of NoV sequences were obtained from the coastal regions of China, and most of the NoV sequences from distinct geographical regions appeared to be closely related. GII.4 was the most prevalent genotype, accounting for 64.4% of all genotypes, followed by GII.12 (13.9%) and GII.3 (7.0%). Over the last decade, the GII.4 variants were dominated by successive circulation of GII.4/2002, GII.4/2004, GII.4/2006b, and GII.4/2008, with GII.4/2006b continuing to date. A relatively high frequency of NoV intergenotype recombinants was identified. The most common ORF1/ORF2 intergenotype recombinant was GII.12/GII.4 (n = 11), and the relative frequency was up to 30% among all the recombinant strains (n = 36). These findings may aid in the evaluation and implementation of appropriate measures for monitoring NoV infectious diseases in China.
    BioMed research international. 01/2014; 2014:196169.


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