Occurrence Of Human Enteric Viruses Research Articles

A study on the occurrence of human enteric viruses in salad vegetables and seafood and associated health risks for consumers in Mauritius.

Norovirus (NOV) and hepatitis A virus (HAV) are human enteric viruses of major concern worldwide. Salad vegetables and molluscan shellfish are highly susceptible to contamination by NOV and HAV and can pose a health threat when consumed raw. The objective of this study was to determine the occurrence of NOV and HAV in lettuce, watercress, tomatoes, and oysters using the enzyme-linked immunosorbent assay and assess the health risks associated with the consumption of these commodities by semiquantitative risk assessment. The occurrence of NOV in vegetables ranked in the following decreasing order: lettuce (36%) > watercress (16%) > tomatoes (4%). However, HAV was more frequently detected in watercress (56%), compared to lettuce or tomatoes (12%). Additionally, NOV was detected in oysters (60%). The risk assessment exercise pointed to a medium-risk score of contracting a foodborne illness of viral origin for consumers eating fresh watercress or oysters. Future research will ascertain the presence of these enteric viruses in a broader range of food commodities.

Occurrence of Human Enteric Viruses in Shellfish along the Production and Distribution Chain in Sicily, Italy.

Contamination of bivalve mollusks with human pathogenic viruses represents a recognized food safety risk. Thus, monitoring programs for shellfish quality along the entire food chain could help to finally preserve the health of consumers. The aim of the present study was to provide up-to-date data on the prevalence of enteric virus contamination along the shellfish production and distribution chain in Sicily. To this end, 162 batches of mollusks were collected between 2017 and 2019 from harvesting areas, depuration and dispatch centers (n = 63), restaurants (n = 6) and retail stores (n = 93) distributed all over the island. Samples were processed according to ISO 15216 standard method, and the presence of genogroup GI and GII norovirus (NoV), hepatitis A and E viruses (HAV, HEV), rotavirus and adenovirus was investigated by real-time reverse transcription polymerase chain reaction (real-time-RT PCR), nested (RT)-PCR and molecular genotyping. Our findings show that 5.56% of samples were contaminated with at least one NoV, HAV and/or HEV. Contaminated shellfish were sampled at production sites and retail stores and their origin was traced back to Spain and several municipalities in Italy. In conclusion, our study highlights the need to implement routine monitoring programs along the whole food chain as an effective measure to prevent foodborne transmission of enteric viruses.

Occurrence of Human Enteric Viruses in Water Sources and Shellfish: A Focus on Africa.

Enteric viruses are a diverse group of human pathogens which are primarily transmitted by the faecal–oral route and are a major cause of non-bacterial diarrhoeal disease in both developed and developing countries. Because they are shed in high numbers by infected individuals and can persist for a long time in the environment, they pose a serious threat to human health globally. Enteric viruses end up in the environment mainly through discharge or leakage of raw or inadequately treated sewage into water sources such as springs, rivers, dams, or marine estuaries. Human exposure then follows when contaminated water is used for drinking, cooking, or recreation and, importantly, when filter-feeding bivalve shellfish are consumed. The human health hazard posed by enteric viruses is particularly serious in Africa where rapid urbanisation in a relatively short period of time has led to the expansion of informal settlements with poor sanitation and failing or non-existent wastewater treatment infrastructure, and where rural communities with limited or no access to municipal water are dependent on nearby open water sources for their subsistence. The role of sewage-contaminated water and bivalve shellfish as vehicles for transmission of enteric viruses is well documented but, to our knowledge, has not been comprehensively reviewed in the African context. Here we provide an overview of enteric viruses and then review the growing body of research where these viruses have been detected in association with sewage-contaminated water or food in several African countries. These studies highlight the need for more research into the prevalence, molecular epidemiology and circulation of these viruses in Africa, as well as for development and application of innovative wastewater treatment approaches to reduce environmental pollution and its impact on human health on the continent.

Occurrence of human e nterovirus in tropical fish and shellfish and their relationship with fecal indicator bacteria.

Aim:Human enteroviruses in fish and shellfish are a health concern worldwide. Human infections occur due to the consumption of raw or insufficiently cooked fish or shellfish. The objective of this study was to determine the occurrence of human enteric viruses belonging to Enterovirus (EV) group in seafood in Mumbai and to correlate their occurrence with the bacterial indicators of fecal contamination.Materials and Methods:Samples of fresh fish and shellfish collected from fish landing centers and retail fish markets were analyzed by virus concentration, nucleic acid extraction, and reverse transcription-polymerase chain reaction (RT-PCR). Bacterial indicators of fecal contamination were estimated by the most probable number technique. The relationship between the presence of virus and fecal indicators was determined by statistical analysis.Results:A total of 89 samples comprising of fish, shrimps, oysters, clams, and mussels were screened in this study. EV was detected in 32 (35.95%) samples, and all the virus-positive samples belonged to bivalve molluscan group. None of the finfish and crustacean shellfish samples was positive for the enteric viruses. Clams were found to be the most contaminated with 48.4% of the samples being positive for EV. The prevalence of enteric viruses in seafood samples showed a strong positive correlation with the bacteriological indicators of fecal contamination, suggesting that fecal coliform bacteria are good indicators of EVs in tropical seafood.Conclusion:The presence of EVs in seafood is a public health hazard. Increasing level of coastal water contamination from anthropogenic sources is the primary reason for the contamination of seafood with EVs. Continuous monitoring of coastal waters and seafood for enteric viruses will help to ensure the safety of fish and shellfish for human consumption.

Enteric viruses' dissemination in a private reserve of natural heritage.

This study is part of a collaborative project designed to investigate the environmental and health conditions of the Private Reserve of Natural Heritage at Pantanal, the largest seasonally flooded wetland in the world. The project aimed to promote health and quality of human and wildlife extending technical-scientific knowledge about pathogens present in the region. By assessing the occurrence of human enteric viruses in different water matrices we demonstrated the anthropogenic impact of surrounding population and pointed out the potential risk of infection by exposure of susceptible individuals.

Distribution of Escherichia coli, coliphages and enteric viruses in water, epilithic biofilms and sediments of an urban river in Germany

Fecal contamination of surface water is commonly evaluated by quantification of bacterial or viral indicators such as Escherichia coli and coliphages, or by direct testing for pathogens such as enteric viruses. Retention of fecally derived organisms in biofilms and sediments is less frequently considered. In this study, we assessed the distribution of E. coli, somatic coliphages, and enteric viruses including human adenovirus (HAdV), enterovirus (EV), norovirus genogroup GII (NoV GII) and group A rotavirus (RoV) in an urban river environment in Germany. 24 samples each of water, epilithic biofilms and sediments were examined. E. coli and somatic coliphages were prevalent not only in the flowing water, but also in epilithic biofilms and sediments, where they were accumulated compared to the overlying water. During enhanced rainfall, E. coli and coliphage concentrations increased by approximately 2.5 and 1 log unit, respectively, in the flowing water, whereas concentrations did not change significantly in epilithic biofilms and sediments. The occurrence of human enteric viruses detected by qPCR was higher in water than in biofilms and sediments. 87.5% of all water samples were positive for HAdV. Enteric viruses found less frequently were EV, RoV and NoV GII in 20.8%, 16.7% and 8.3% of the water samples, respectively. In epilithic biofilms and sediments, HAdV was found in 54.2% and 50.0% of the samples, respectively, and EV was found in 4.2% of both biofilm and sediment samples. RoV and NoV GII were not detected in any of the biofilms and sediments. Overall, the prevalence of enteric viruses was in the order of HAdV > EV > RoV ≥ NoV GII. In conclusion, epilithic biofilms and sediments can be reservoirs for fecal indicators and enteric viruses and thus should be taken into consideration when assessing microbial pollution of surface water environments.

Occurrence of human enteric viruses at freshwater beaches during swimming season and its link to water inflow

Human enteric viruses are significant etiological agents for many recreational waterborne illnesses. The occurrence and density of human enteric viruses such as human adenovirus (HAdV), human enterovirus (HEnV), and human norovirus genogroups I/II (HNoV GI/GII) were investigated using quantitative real-time PCR (qPCR) at freshwater beaches along with monitoring fecal indicators and environmental parameters. During the 2009 swimming season, water samples were collected from three inland freshwater beaches in Ohio, USA. Of the total samples, 40% (26/65) and 17% (11/65) were positive for HAdV and HEnV respectively, but HNoV GI/GII were not detected. There was no significant association among the detected human enteric viruses (HAdV and HEnV) and fecal bacteria indicators (Escherichia coli and Bacteroides) by Spearman correlation and principal component analyses. Logistic regression analysis also revealed that the odds of finding HAdV or HEnV was not influenced by levels of fecal bacteria indicators. However, there was a 14-fold increase in the odds of HEnV detection for each 1-log increase in daily water inflow (m3/s) into freshwater beach reservoirs (adjusted odds ratio=14.2; 95% confidence interval=1.19–171). In summary, the viral occurrence at the freshwater beaches was not readily explained by the levels of fecal bacteria indicators, but appeared to be more related to water reservoir inflows. These results suggest that hydrological data must be considered in future epidemiology efforts aimed at characterizing beach water safety.

Harmonised Investigation of the Occurrence of Human Enteric Viruses in the Leafy Green Vegetable Supply Chain in Three European Countries

Numerous outbreaks have been attributed to the consumption of raw or minimally processed leafy green vegetables contaminated with enteric viral pathogens. The aim of the present study was an integrated virological monitoring of the salad vegetables supply chain in Europe, from production, processing and point-of-sale. Samples were collected and analysed in Greece, Serbia and Poland, from 'general' and 'ad hoc' sampling points, which were perceived as critical points for virus contamination. General sampling points were identified through the analysis of background information questionnaires based on HACCP audit principles, and they were sampled during each sampling occasion where as-ad hoc sampling points were identified during food safety fact-finding visits and samples were only collected during the fact-finding visits. Human (hAdV) and porcine (pAdV) adenovirus, hepatitis A (HAV) and E (HEV) virus, norovirus GI and GII (NoV) and bovine polyomavirus (bPyV) were detected by means of real-time (RT-) PCR-based protocols. General samples were positive for hAdV, pAdV, HAV, HEV, NoV GI, NoV GII and bPyV at 20.09 % (134/667), 5.53 % (13/235), 1.32 % (4/304), 3.42 % (5/146), 2 % (6/299), 2.95 % (8/271) and 0.82 % (2/245), respectively. Ad hoc samples were positive for hAdV, pAdV, bPyV and NoV GI at 9 % (3/33), 9 % (2/22), 4.54 % (1/22) and 7.14 % (1/14), respectively. These results demonstrate the existence of viral contamination routes from human and animal sources to the salad vegetable supply chain and more specifically indicate the potential for public health risks due to the virus contamination of leafy green vegetables at primary production.

Occurrence of Human Enteric Viruses in Commercial Mussels at Retail Level in Three European Countries

In this study, the prevalence of different enteric viruses in commercial mussels was evaluated at the retail level in three European countries (Finland, Greece and Spain). A total of 153 mussel samples from different origins were analysed for human norovirus (NoV) genogroups I and II, hepatitis A virus (HAV) and hepatitis E virus (HEV). Human adenovirus (HAdV) was also tested as an indicator of human faecal contamination. A full set of controls (such as sample process control, internal amplification controls, and positive and negative controls) were implemented during the process. The use of a sample process control allowed us to calculate the efficiencies of extraction, which ranged from 79 to 0.5 %, with an average value of 10 %. Samples were positive in 41 % of cases, with HAdV being the most prevalent virus detected (36 %), but no significant correlation was found between the presence of HAdV and human NoV, HAV and HEV. The prevalences of human norovirus genogroup II, HEV and human NoV genogroup I were 16, 3 and 0.7 %, respectively, and HAV was not detected. The estimated number of PCR detectable units varied between 24 and 1.4 × 10(3) g(-1) of digestive tract. Interestingly, there appeared to be a significant association between the type of mussel species (M. galloprovincialis) and the positive result of samples, although a complete overlap between country and species examined required this finding to be confirmed including samples of both species from all possible countries of origin.

Seasonal Occurrence of Human Enteric Viruses in River Water Samples Collected from Rural Areas of South-East Poland

The study was carried out in 2007, and its main aim was 1 year monitoring of surface water of the River Wieprz in Poland for the presence of human adenoviruses group F and noroviruses (NoVs). In total, 60 water samples were collected from four sampling sites situated along the river. The viruses were concentrated from water samples using glass wool, followed by elution with a glycine buffer containing skimmed milk powder. Subsequently, the viral nucleic acids were extracted and purified from water concentrates using a NucliSENS® kit and a QIAamp Viral RNA Mini Kit®. The presence of viral nucleic acids was confirmed by applying traditional PCR-based methods with incorporated internal amplification controls. Human pathogenic viruses were detected in 35% of analysed water samples. Adenoviruses were detected in 28.3% of analysed samples, and were present at all seasons of the year. 11.6% of the samples were positive for NoVs; they were present only during summer, in contrast to conventional findings. Molecular identification of norovirus strains revealed that they belong to genogroup I and II.

Assessment of Sewer Source Contamination of Drinking Water Wells Using Tracers and Human Enteric Viruses

This study investigated the source, transport, and occurrence of human enteric viruses in municipal well water, focusing on sanitary sewer sources. A total of 33 wells from 14 communities were sampled once for wastewater tracers and viruses. Wastewater tracers were detected in four of these wells, and five wells were virus- positive by qRT-PCR. These results, along with exclusion of wells with surface water sources, were used to select three wells for additional investigation. Viruses and wastewater tracers were found in the groundwater at all sites. Some wastewater tracers, such as ionic detergents, flame retardants, and cholesterol, were considered unambiguous evidence of wastewater. Sampling at any given time may not show concurrent virus and tracer presence; however, given sufficient sampling over time, a relation between wastewater tracers and virus occurrence was identified. Presence of infectious viruses at the wellhead demonstrates that high-capacity pumping induced sufficiently short travel times for the transport of infectious viruses. Therefore, drinking-water wells are vulnerable to contaminants that travel along fast groundwater flowpaths even if they contribute a small amount of virus-laden water to the well. These results suggest that vulnerability assessments require characterization of "low yield-fast transport" in addition to traditional "high yield-slow transport", pathways.

Virus Transport Experiments in a Sandy Aquifer

The occurrence of human enteric viruses in ground water has been well documented in the literature. Bacteriophages such as MS-2 and PRD1 have properties similar to pathogenic human viruses suggesting that bacteriophages can be used as proxies for virus transport. The objective of this study is to investigate a “worst case scenario” for virus transport in a ground water aquifer, i.e., sand and gravel aquifer under a forced-gradient, by using bacteriophages. Field studies have been conducted to trace large-scale (34 m) and small-scale (10 m) virus transport under natural- and forced-gradients through a sand and gravel aquifer at a ground water research site at the Texas A&M University. Virus transport was monitored under natural and forced-gradient conditions using MS-2 and PRD-1 as virus tracers and bromide as a conservative tracer. Results indicate virus and bromide transport to down-gradient monitoring wells in both the large- and small-scale field tests. During the tests conducted, MS-2 transport appears to exhibit little longitudinal dispersion, showing a narrow peak at the well nest 34 m down-gradient in 13 days which is 20 days before the bromide breakthroughs, indicating that bacteriophage transport through the aquifer was mainly by advective flow. Differences in tracer transport can be attributed to the heterogeneity of the sand and gravel aquifer at the site, different injection methods, different sampling methods, and different tracer properties. Heterogeneity of the aquifer would cause virus transport through preferential flow paths.

Application of Cation-Coated Filter Method to Detection of Noroviruses, Enteroviruses, Adenoviruses, and Torque Teno Viruses in the Tamagawa River in Japan

The occurrence of human enteric viruses in surface water in the Tamagawa River, Japan, was surveyed for 1 year, from April 2003 to March 2004. Sixty-four samples were collected from six sites along the river, and 500 ml of the sample was concentrated using the cation-coated filter method, which was developed in our previous study. This method showed recovery yields of 56% +/- 32% (n = 37) for surface water samples inoculated with polioviruses. More than one kind of tested virus was detected in 43 (67%) of 64 samples by TaqMan PCR. Noroviruses and adenoviruses were detected in a high positive ratio; 34 (53%), 28 (44%), and 29 (45%) of 64 samples were positive for norovirus genotype 1 and genotype 2 and adenoviruses, respectively. The mean concentrations of norovirus genotype 1 or genotype 2 determined by real-time PCR were 0.087 and 0.61 genome/ml, respectively, showing much higher values in winter (0.21 genome/ml for genotype 1 and 2.3 genomes/ml for genotype 2). Enteroviruses were detected by both direct PCR (6 of 64 samples; 9%) and cell culture PCR (2 of 64 samples; 3%). Torque teno viruses, emerging hepatitis viruses, were also isolated in three samples (5%). The concentration of total coliforms and the presence of F-specific phages showed a high correlation with the presence of viruses, which suggested that the simultaneous use of total coliforms and F-specific phages as indicators of surface water may work to monitor viral contamination.