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: 2.36). 12/2012; 4(4):131-52. DOI: 10.1007/s12560-012-9091-z
Source: PubMed


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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    • "Overview of bovine noroviruses detected worldwide (adapted from Mathijs et al., 2012). "

    • "In the wider community, NoV GGII has been associated with the majority of recorded gastroenteritis cases (Lopman et al., 2004). Person-to-person transmission is the most common pathway, but NoV is spread by several routes that include contaminated shellfish, fresh food, processed food and water (Mathijs et al., 2012). NoVs are highly infectious, with a single virus particle having a probability of infection approaching 49% (Teunis et al., 2008). "
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    ABSTRACT: Conventional wastewater treatment does not completely remove and/or inactive viruses; consequently, viruses excreted by the population can be detected in the environment. This study was undertaken to investigate the distribution and seasonality of human viruses and faecal indicator bacteria (FIB) in a river catchment located in a typical Mediterranean climate region and to discuss future trends in relation to climate change. Sample matrices included river water, untreated and treated wastewater from a wastewater treatment plant within the catchment area, and seawater from potentially impacted bathing water. Five viruses were analysed in the study. Human adenovirus (HAdV) and JC polyomavirus (JCPyV) were analysed as indicators of human faecal contamination of human pathogens; both were reported in urban wastewater (mean values of 10(6) and 10(5) GC/L, respectively), river water (10(3) and 10(2) GC/L) and seawater (10(2) and 10(1) GC/L). Human Merkel Cell polyomavirus (MCPyV), which is associated with Merkel Cell carcinoma, was detected in 75% of the raw wastewater samples (31/37) and quantified by a newly developed quantitative polymerase chain reaction (qPCR) assay with mean concentrations of 10(4) GC/L. This virus is related to skin cancer in susceptible individuals and was found in 29% and 18% of river water and seawater samples, respectively. Seasonality was only observed for norovirus genogroup II (NoV GGII), which was more abundant in cold months with levels up to 10(4) GC/L in river water. Human hepatitis E virus (HEV) was detected in 13.5% of the wastewater samples when analysed by nested PCR (nPCR). Secondary biological treatment (i.e., activated sludge) and tertiary sewage disinfection including chlorination, flocculation and UV radiation removed between 2.22 and 4.52 log10 of the viral concentrations. Climate projections for the Mediterranean climate areas and the selected river catchment estimate general warming and changes in precipitation distribution. Persistent decreases in precipitation during summer can lead to a higher presence of human viruses because river and sea water present the highest viral concentrations during warmer months. In a global context, wastewater management will be the key to preventing environmental dispersion of human faecal pathogens in future climate change scenarios. Copyright © 2015. Published by Elsevier Ltd.
    Journal of Environmental Management 06/2015; 159:58-67. DOI:10.1016/j.jenvman.2015.05.019 · 2.72 Impact Factor
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    • "Various food products such as bivalve mollusks (especially oysters) (Le Guyader et al., 2010; Thebault et al., 2013), fresh fruit and vegetables including different types of lettuce, onions, berries and, more recently, semidried tomatoes have been involved in foodborne disease outbreaks (Bernard et al., 2014; Ethelberg et al., 2010; Fournet et al., 2012; Gallot et al., 2011; Sarvikivi et al., 2012). Fruits and vegetables can be contaminated either at the pre-harvest stage through contact with fecally contaminated irrigation water or during harvesting, packaging, processing, or cooking due to poor hand sanitation (Bitler et al., 2013; Kotwal and Cannon, 2014; Mathijs et al., 2012; Rodriguez-Lazaro et al., 2012). Most foodborne viruses are difficult or currently impossible to cultivate (Hamza et al., 2011) and sensitive molecular methods are therefore used to detect them in food and environmental samples. "
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    ABSTRACT: Noroviruses (genogroup I (NoV GI) and genogroup II (NoV GII)) and the hepatitis A virus (HAV) are frequently involved in foodborne infections worldwide. They are mainly transmitted via the fecal-oral route, direct person-to-person contact or consumption of contaminated water and foods. In food virology, detection methods are currently based on identifying viral genomes using real-time reverse transcriptase PCR (RT-qPCR). One of the general requirements for detecting these viruses in food involves the use of a process control virus to monitor the quality of the entire viral extraction procedure as described in the ISO/TS 15216-1 and 15216-2 standards published in 2013. The selected process control virus should have similar morphological and physicochemical properties as the screened pathogenic virus and thus have the potential to provide comparable extraction efficiency. The aim of this study was to determine which virus should be used for process control, murine norovirus (MNV-1) or Mengovirus, when testing for the presence of HAV, NoV GI and NoV GII in bottled water, lettuce and semi-dried tomatoes. Food samples were spiked with HAV, NoV GI or NoV GII alone or in the presence of MNV-1 or Mengovirus. Recovery rates of each pathogenic virus were compared to those of both process control viruses using a multiple comparison procedure. Neither process control virus influenced the recovery of pathogenic virus regardless of the type of food matrix. MNV-1 was the most appropriate virus for validating the detection of HAV and NoV GII in all three food matrices as well as NoV GI in lettuce. Mengovirus proved to be the most appropriate control for NoV GI detection in bottled water and semi-dried tomatoes. The process control virus is essential for validating viral detection in food and the choice of virus depends on food type and the screened pathogenic virus. Copyright © 2015 Elsevier B.V. All rights reserved.
    International Journal of Food Microbiology 02/2015; 202:57-65. DOI:10.1016/j.ijfoodmicro.2015.02.029 · 3.08 Impact Factor
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