Article

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

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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Available from: Ambroos Stals, Oct 07, 2014
    • "Overview of bovine noroviruses detected worldwide (adapted from Mathijs et al., 2012). "
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    ABSTRACT: Noroviruses are RNA viruses that belong to the Genus Norovirus, Family Caliciviridae, and infect human beings and several animal species, including cattle. Bovine norovirus infections have been detected in cattle of a range of different ages throughout the world. Currently there is no suitable cell culture system for these viruses and information on their pathogenesis is limited. Molecular and serological tests have been developed, but are complicated by the high genetic and antigenic diversity of bovine noroviruses. Bovine noroviruses can be detected frequently in faecal samples of diarrhoeic calves, either alone or in association with other common enteric pathogens, suggesting a role for these viruses in the aetiology of calf enteritis.
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    • "strains are detected most commonly in association with disease (Patel et al., 2009), although there is a greater diversity of genotypes associated with foodborne outbreaks (Kroneman et al., 2008; Stals et al., 2012). Most hNoV foodborne disease outbreaks are associated with consumption of food outside of the home, where it appears that poor hygiene of infected food handlers is the major source of contamination (Mathijs et al., 2012). Effective control measures for water treatment, food processing , cleaning and disinfection of surfaces, personal hygiene and hand washing, and/or sanitation are all required in order to control the spread of hNoV along the food chain, although the efficiency of current control measures is poorly characterized. "
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    ABSTRACT: Human noroviruses (hNoV) are the single largest cause of acute gastroenteritis in the western world. The efficacy of hNoV control measures remains largely unknown, partly owing to the inability to grow the virus in vitro and partly to the large number of surrogate studies of unknown relevance. A systematic review of the persistence and survival of hNoV in foods and the environment was undertaken based upon PRISMA (preferred reporting items for systematic reviews and meta analyses) guidelines to answer the questions: (1) "What are the natural hNoV persistence characteristics in food and the environment?" and (2) "How can these properties be altered by applying physical and/or chemical treatments to foods or food contact surfaces?" Over 10,000 citations were screened using defined inclusion and exclusion criteria. One hundred and twenty-six (126) citations were identified for further evaluation and data were extracted based upon the conditions of study and treatment (e.g., treatment parameters, pH, and temperature, time, infectivity, and RT-qPCR results). Since the only markers for hNoV persistence and survival were RT-qPCR data and human challenge studies, citations for further analysis were restricted to only those that included data on hNoV behavior (using RT-qPCR) as compared directly to surrogate virus behavior (using both RT-qPCR and infectivity) in the same study, and clinical studies. Based on these criteria, a total of 12 independent studies (5 for thermal inactivation and 7 for available chlorine) and 3 human challenge studies were identified. RT-qPCR always underestimated reductions in surrogate virus titre as a function of treatment when compared to infectivity. The corresponding reductions in RT-qPCR signals for hNoV under comparable conditions were nearly always less than those observed for the surrogates. These relationships were statistically significant for heat when comparing persistence of hNoV RT-qPCR signals with surrogate MNV-1 RT-qPCR signals (P equal persistence=<0.07); and for free chlorine when comparing persistence of hNoV RT-qPCR signals to those of FCV F-9 (p=<0.01). Overall the data suggest that hNoV are frequently more resistant to typical food and environmental control measures compared with cultivable surrogate viruses, when basing data on comparative RT-qPCR results.
    No preview · Article · Sep 2015 · International journal of food microbiology
    • "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.
    No preview · Article · Jun 2015 · Journal of Environmental Management
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