Molecular detection and genotyping of human noroviruses in influent and effluent water at a wastewater treatment plant in Japan

Estimation of Norovirus infections in Japan: An application of wastewater-based epidemiology for enteric disease assessment

Noroviruses of genogroup I (NoV GI) and NoV GII are the primary causes of acute gastroenteritis (AGE) in developed countries. However, asymptomatic and untested NoV infections lead to an underestimation of AGE cases, and the lack of mandatory viral identification in clinical cases hinders precise estimation of NoV infections. Back estimation of NoV infections in the community using a wastewater-based epidemiology (WBE) approach can provide valuable insights into the disease's extent, progression, and epidemiology, aiding in developing effective control strategies. This study employed a one-step reverse transcription-quantitative PCR to quantify NoVs GI and GII in wastewater samples (n = 83) collected twice a week from June 2022 to March 2023 in Japan. All samples from the Winter-Spring (n = 27) tested positive for NoV GI and GII RNA, while 73 % and 88 % of samples from the Summer-Autumn (n = 56) were positive for NoV GI and NoV GII RNA, respectively. Significantly higher concentrations of NoV GI/GII RNA were found in the Winter-Spring season compared to the Summer-Autumn season. NoV RNA was consistently detected in wastewater throughout the year, demonstrating the persistence of AGE cases in the catchment, suggesting an endemic NoV infection. Estimates of NoV infection incorporated viral RNA concentrations, wastewater parameters, and signal persistence in a mass balance equation using Monte Carlo Simulation. The median estimated NoV GI infections per 100,000 population for Summer-Autumn was 133 and for the Winter-Spring season, it was 881. Estimated NoV GII infections were 1357 for Summer-Autumn and 11,997 for the Winter-Spring season per 100,000 population. The estimated NoV infections exceeded by 3.2 and 23.9 folds than the reported AGE cases in Summer-Autumn and Winter-Spring seasons, respectively. The seasonal trend of estimated NoV infections closely matched that of AGE cases, highlighting the utility of WBE in understanding the epidemiology of enteric infections.

Prevalence of Human Norovirus GII.4 Sydney 2012 [P31] between 2019 and 2021 among Young Children from Rural Communities in South Africa

Acute gastroenteritis (AGE) accounts for considerable morbidity and mortality in the paediatric population worldwide, especially in low-income countries. Human norovirus (HNoV), particularly GII.4 strains, are important agents of AGE. This study aimed to detect and characterise HNoV in children with and without AGE. Between 2019 and 2021, 300 stool samples (200 AGE and 100 without AGE) were collected from children below 5 years of age referred to the healthcare facilities of the rural communities of Vhembe District, South Africa. After detection using real-time RT-PCR, HNoV positive samples were subjected to RT-PCR and Sanger sequencing. Partial nucleotide sequences (capsid/RdRp) were aligned using the Muscle tool, and phylogenetic analysis was performed using MEGA 11. The nucleotides' percent identity among HNoV strains was compared using ClustalW software. A significant difference in HNoV prevalence between AGE children (37%; 74/200) and non-AGE (14%; 14/100) was confirmed (p < 0.0001). Genogroup II (GII) HNoV was predominant in AGE children (80%; 59/74), whereas most non-AGE children were infected by the GI norovirus genogroup (64%; 9/14). GII.4 Sydney 2012 [P31] strains were dominant (59%; 19/32) during the study period. A phylogenetic analysis revealed a close relationship between the HNoV strains identified in this study and those circulating worldwide; however, ClustalW showed less than 50% nucleotide similarity between strains from this study and those from previously reported norovirus studies in the same region. Our findings indicate significant changes over time in the circulation of HNoV strains, as well as the association between high HNoV prevalence and AGE symptoms within the study area. The monitoring of HuNoV epidemiology, along with stringent preventive measures to mitigate the viral spread and the burden of AGE, are warranted.

Sheet, Surveillance, Strategy, Salvage and Shield in global biodefense system to protect the public health and tackle the incoming pandemics

The pandemic of COVID-19 challenges the global health system and raises our concerns on the next waves of other emerging infectious diseases. Considering the lessons from the failure of world's pandemic warning system against COVID-19, many scientists and politicians have mentioned different strategies to improve global biodefense system, among which Sheet, Surveillance, Strategy, Salvage and Shield (5S) are frequently discussed. Nevertheless, the current focus is mainly on the optimization and management of individual strategy, and there are limited attempts to combine the five strategies as an integral global biodefense system. Sheet represents the biosafety datasheet for biohazards in natural environment and human society, which helps our deeper understanding on the geographical pattern, transmission routes and infection mechanism of pathogens. Online surveillance and prognostication network is an environmental Surveillance tool for monitoring the outbreak of pandemic diseases and alarming the risks to take emergency actions, targeting aerosols, waters, soils and animals. Strategy is policies and legislations for social distancing, lockdown and personal protective equipment to block the spread of infectious diseases in communities. Clinical measures are Salvage on patients by innovating appropriate medicines and therapies. The ultimate defensive Shield is vaccine development to protect healthy crowds from infection. Fighting against COVID-19 and other emerging infectious diseases is a long rocky journey, requiring the common endeavors of scientists and politicians from all countries around the world. 5S in global biodefense system bring a ray of light to the current darkest and future road from environmental and geographical perspectives.

Norovirus detection in wastewater and its correlation with human gastroenteritis: a systematic review and meta-analysis

Norovirus (NoV) is a major cause of sporadic cases and outbreaks of acute gastroenteritis (AGE), thereby imposing threat to health globally. It is unclear how quantitation of wastewater NoV reflects the incidence of human AGE infections; therefore, we conducted this systematic review and meta-analysis of published NoV wastewater surveillance studies. A literature search was performed, and all studies on NoV wastewater surveillance were identified. Quantitative results were evaluated. The results showed that the overall detection rate of NoV in wastewater was 82.10% (95% confidence interval [CI]: 74.22-89.92%); NoV concentration was statistically significant in terms of season (P < 0.001), with higher concentration in spring and winter. There were positive correlations between NoV GII concentration in wastewater and GII AGE cases (rs = 0.51, 95% CI: 0.18-0.74, I2 = 0%), total AGE cases (rs = 0.40, 95% CI: 0.15-0.61, I2 = 23%) and NoV outbreaks (rs = 0.47, 95% CI: 0.30-0.62, I2 = 0%). Results of cross-correlation analysis of partial data indicated that variations in GII concentration were consistent with or ahead of those in the number of AGE cases. The diversity of NoV genotypes in wastewater was elucidated, and the dominant strains in wastewater showed a consistent temporal distribution with those responsible for human AGE. Our study demonstrated the potential association of NoV detected in wastewater with AGE infections, and further studies are needed to confirm this conclusion.

Environmental Surveillance of SARS-CoV-2 RNA in Wastewater and Groundwater in Quintana Roo, Mexico

The presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in wastewater has been reported as a result of fecal shedding of infected individuals. In this study, the occurrence of SARS-CoV-2 RNA was explored in primary-treated wastewater from two municipal wastewater treatment plants in Quintana Roo, Mexico, along with groundwater from sinkholes, a household well, and submarine groundwater discharges. Physicochemical variables were obtained in situ, and coliphage densities were determined. Three virus concentration methods based on adsorption-elution and sequential filtration were used followed by RNA isolation. Quantification of SARS-CoV-2 was done by RT-qPCR using the CDC 2020 assay, 2019-nCoV_N1 and 2019-nCoV_N2. The Pepper mild mottle virus, one of the most abundant RNA viruses in wastewater was quantified by RT-qPCR and compared to SARS-CoV-2 concentrations. The use of three combined virus concentration methods together with two qPCR assays allowed the detection of SARS-CoV-2 RNA in 58% of the wastewater samples analyzed, whereas none of the groundwater samples were positive for SARS-CoV-2 RNA. Concentrations of SARS-CoV-2 in wastewater were from 1.8 × 10³ to 7.5 × 10³ genome copies per liter (GC l^-1), using the N1 RT-qPCR assay, and from 2.4 × 10² to 5.9 × 10³ GC l^-1 using the N2 RT-qPCR assay. Based on PMMoV prevalence detected in all wastewater and groundwater samples tested, the three viral concentration methods used could be successfully applied for SARS-CoV-2 RNA detection in further studies. This study represents the first detection of SARS-CoV-2 RNA in wastewater in southeast Mexico and provides a baseline for developing a wastewater-based epidemiology approach in the area.

Bacteriophages Are Good Estimators of Human Viruses Present in Water

The detection of fecal viral pathogens in water is hampered by their great variety and complex analysis. As traditional bacterial indicators are poor viral indicators, there is a need for alternative methods, such as the use of somatic coliphages, which have been included in water safety regulations in recent years. Some researchers have also recommended the use of reference viral pathogens such as noroviruses or other enteric viruses to improve the prediction of fecal viral pollution of human origin. In this work, phages previously tested in microbial source tracking studies were compared with norovirus and adenovirus for their suitability as indicators of human fecal viruses. The phages, namely those infecting human-associated Bacteroides thetaiotaomicron strain GA17 (GA17PH) and porcine-associated Bacteroides strain PG76 (PGPH), and the human-associated crAssphage marker (crAssPH), were evaluated in sewage samples and fecal mixtures obtained from different animals in five European countries, along with norovirus GI + GII (NoV) and human adenovirus (HAdV). GA17PH had an overall sensitivity of ≥83% and the highest specificity (>88%) for human pollution source detection. crAssPH showed the highest sensitivity (100%) and specificity (100%) in northern European countries but a much lower specificity in Spain and Portugal (10 and 30%, respectively), being detected in animal wastewater samples with a high concentration of fecal indicators. The correlations between GA17PH, crAssPH, or the sum of both (BACPH) and HAdV or NoV were higher than between the two human viruses, indicating that bacteriophages are feasible indicators of human viral pathogens of fecal origin and constitute a promising, easy to use and affordable alternative to human viruses for routine water safety monitoring.

Understanding Pediatric Norovirus Epidemiology: A Decade of Study among Ghanaian Children

Understanding the epidemiology of human norovirus infection in children within Ghana and the entire sub-Saharan African region, where future norovirus vaccines would have the greatest impact, is essential. We analyzed 1337 diarrheic stool samples collected from children <5 years from January 2008 to December 2017 and found 485 (36.2%) shedding the virus. GII.4 (54.1%), GII.3 (7.7%), GII.6 (5.3%), GII.17 (4.7%), and GII.5 (4.7%) were the most common norovirus genotypes. Although norovirus GII.4 remained the predominant capsid genotype throughout the study period, an increase in GII.6 and GII.3 capsid genotypes was observed in 2013 and 2014, respectively. The severity of clinical illness in children infected with GII.4 norovirus strains was similar to illness caused by non-GII.4 strains. Since the epidemiology of norovirus changes rapidly, establishment of systematic surveillance within sentinel sites across the country would enhance the monitoring of circulating norovirus strains and allow continuous understanding of norovirus infection in Ghana.

Applicability of crAssphage, pepper mild mottle virus, and tobacco mosaic virus as indicators of reduction of enteric viruses during wastewater treatment

This study was conducted to evaluate the applicability of crAssphage, pepper mild mottle virus (PMMoV), and tobacco mosaic virus (TMV) as indicators of the reduction of human enteric viruses during wastewater treatment. Thirty-nine samples were collected from three steps at a wastewater treatment plant (raw sewage, secondary-treated sewage, and final effluent) monthly for a 13-month period. In addition to the three indicator viruses, eight human enteric viruses [human adenoviruses, JC and BK polyomaviruses, Aichi virus 1 (AiV-1), enteroviruses, and noroviruses of genogroups I, II, and IV] were tested by quantitative PCR. Indicator viruses were consistently detected in the tested samples, except for a few final effluents for crAssphage and TMV. The mean concentrations of crAssphage were significantly higher than those of most tested viruses. The concentrations of crAssphage in raw sewage were positively correlated with the concentrations of all tested human enteric viruses (p <0.05), suggesting the applicability of crAssphage as a suitable indicator to estimate the concentrations of human enteric viruses in raw sewage. The reduction ratios of AiV-1 (1.8 ± 0.7 log₁₀) were the lowest among the tested viruses, followed by TMV (2.0 ± 0.3 log₁₀) and PMMoV (2.0 ± 0.4 log₁₀). Our findings suggested that the use of not only AiV-1 and PMMoV but also TMV as indicators of reductions in viral levels can be applicable during wastewater treatment.

Bathing Activities and Microbiological River Water Quality in the Paris Area: A Long-Term Perspective

This chapter presents the historical aspects regarding swimming in rivers in the Paris region since the seventeenth century, including the concept of fecal contamination indicator bacteria (FIBs) developed at the very beginning of the twentieth century, and historical contamination data covering more than one century in the Paris agglomeration. The sources of microbiological contamination of river waters are quantified, showing the importance of rain events. The present contamination levels are presented with reference to the European Directive for bathing water quality. FIB levels show that the sufficient quality for bathing is not reached yet in any of the monitored stations. A comprehensive data set regarding waterborne pathogens (viruses, Giardia, Cryptosporidium) in the Seine and Marne rivers is presented as a necessary complement to the regulatory FIB data to better evaluate health risks. The last section concludes on the actions to be conducted to improve the rivers’ microbiological quality in the coming years.

Occurrence of norovirus genogroups I and II in recreational water from four beaches in Belém city, Brazilian Amazon region

This study aimed to investigate the presence of norovirus (NoV) in recreational waters of four estuarine beaches located in Mosqueiro Island, Belém city, Brazilian Amazon, during two years of monitoring (2012 and 2013). NoV particles were concentrated on filtering membrane by the adsorption-elution method and detected by semi-nested RT-PCR (reverse transcription polymerase chain reaction) and sequencing. NoV positivity was observed in 37.5% (39/104) of the surface water samples, with genogroup GI (69.2%) occurring at a higher frequency than GII (25.7%), with a cocirculation of both genogroups in two samples (5.1%). This virus was detected in all sampling points analyzed, showing the highest detection rate at the Paraíso Beach (46.2%). Statistically, there was a dependence relationship between tide levels and positive detection, with a higher frequency at high tide (46.7%) than at low tide (25%) periods. Months with the highest detection rates (April 2012 and April/May 2013) were preceded by periods of higher precipitation (March 2012 and February/March 2013). Phylogenetic analysis showed the circulation of the old pandemic variant (GII.4-US_95-96) and GI.8. The NoV detection demonstrated viral contamination on the beaches and evidenced the health risk to bathers, mainly through recreational activities such as bathing, and highlighted the importance of including enteric viruses research in the recreational water quality monitoring.

The Impact of Winter Relocation and Depuration on Norovirus Concentrations in Pacific Oysters Harvested from a Commercial Production Site

Oysters contaminated with norovirus present a significant public health risk when consumed raw. In this study, norovirus genome copy concentrations were determined in Pacific oysters (Magallana gigas) harvested from a sewage-impacted production site and then subjected to site-specific management procedures. These procedures consisted of relocation of oysters to an alternative production area during the norovirus high-risk winter periods (November to March) followed by an extended depuration (self-purification) under controlled temperature conditions. Significant differences in norovirus RNA concentrations were demonstrated at each point in the management process. Thirty-one percent of oyster samples from the main harvest area (Site 1) contained norovirus concentrations > 500 genome copies/g and 29% contained norovirus concentrations < 100 genome copies/g. By contrast, no oyster sample from the alternative harvest area (Site 2) or following depuration contained norovirus concentrations > 500 genome copies/g. In addition, 60 and 88% of oysters samples contained norovirus concentrations < 100 genome copies/g in oysters sampled from Site 2 and following depuration, respectively. These data demonstrate that site-specific management processes, supported by norovirus monitoring, can be an effective strategy to reduce, but not eliminate, consumer exposure to norovirus genome copies.

A review on recent progress in the detection methods and prevalence of human enteric viruses in water

Waterborne human enteric viruses, such as noroviruses and adenoviruses, are excreted in the feces of infected individuals and transmitted via the fecal-oral route including contaminated food and water. Since viruses are normally present at low concentrations in aquatic environments, they should be concentrated into smaller volumes prior to downstream molecular biological applications, such as quantitative polymerase chain reaction (qPCR). This review describes recent progress made in the development of concentration and detection methods of human enteric viruses in water, and discusses their applications for providing a better understanding of the prevalence of the viruses in various types of water worldwide. Maximum concentrations of human enteric viruses in water that have been reported in previous studies are summarized to assess viral abundances in aquatic environments. Some descriptions are also available on recent applications of sequencing analyses used to determine the genetic diversity of viral genomes in water samples, including those of novel viruses. Furthermore, the importance and significance of utilizing appropriate process controls during viral analyses are discussed, and three types of process controls are considered: whole process controls, molecular process controls, and (reverse transcription (RT)-)qPCR controls. Although no standards have been established for acceptable values of virus recovery and/or extraction-(RT-)qPCR efficiency, use of at least one of these appropriate control types is highly recommended for more accurate interpretation of observed data.

Water-Mediated Transmission of Plant, Animal, and Human Viruses

Viruses represent the most abundant and diverse of the biological entities in environmental waters, including the seas and probably also freshwater systems. They are important players in ecological networks in waters and influence global biochemical cycling and community composition dynamics. Among the many diverse viruses from terrestrial environments found in environmental waters, some are plant, animal, and/or human pathogens. The majority of pathogenic viral species found in waters are very stable and can survive outside host cells for long periods. The occurrence of such viruses in environmental waters has raised concerns because of the confirmation of the infectivity of waterborne viruses even at very low concentrations. This chapter focuses mainly on the survival of human, animal, and plant pathogenic viruses in aqueous environments, the possibility of their water-mediated transmission, the ecological implications of viruses in water, the methods adapted for detecting such viruses, and how to minimize the risk of viruses spreading through water.

Virological Quality of Irrigation Water Sources and Pepper Mild Mottle Virus and Tobacco Mosaic Virus as Index of Pathogenic Virus Contamination Level

Irrigation water is a doorway for the pathogen contamination of fresh produce. We quantified pathogenic viruses [human adenoviruses, noroviruses of genogroups I and II, group A rotaviruses, Aichi virus 1 (AiV-1), enteroviruses (EnVs), and salivirus (SaliV)] and examined potential index viruses [JC and BK polyomaviruses (JCPyVs and BKPyVs), pepper mild mottle virus (PMMoV), and tobacco mosaic virus (TMV)] in irrigation water sources in the Kathmandu Valley, Nepal. River, sewage, wastewater treatment plant (WWTP) effluent, pond, canal, and groundwater samples were collected in September 2014, and in April and August 2015. Viruses were concentrated using an electronegative membrane-vortex method and quantified using TaqMan (MGB)-based quantitative PCR (qPCR) assays with murine norovirus as a molecular process control to determine extraction-reverse transcription-qPCR efficiency. Tested pathogenic viruses were prevalent with maximum concentrations of 5.5-8.8 log₁₀ copies/L, and there was a greater abundance of EnVs, SaliV, and AiV-1. Virus concentrations in river water were equivalent to those in sewage. Canal, pond, and groundwater samples were found to be less contaminated than river, sewage, and WWTP effluent. Seasonal dependency was clearly evident for most of the viruses, with peak concentrations in the dry season. JCPyVs and BKPyVs had a poor detection ratio and correspondence with pathogenic viruses. Instead, the frequently proposed PMMoV and the newly proposed TMV were strongly predictive of the pathogen contamination level, particularly in the dry season. We recommend utilizing canal, pond, and groundwater for irrigation to minimize deleterious health effects and propose PMMoV and TMV as indexes to elucidate pathogenic virus levels in environmental samples.

Environmental Surveillance for Noroviruses in Selected South African Wastewaters 2015-2016: Emergence of the Novel GII.17

Norovirus (NoV) GII.4 is the predominant genotype associated with gastroenteritis pandemics and new strains emerge every 2-3 years. Between 2008 and 2011, environmental studies in South Africa (SA) reported NoVs in 63% of the sewage-polluted river water samples. The aim of this study was to assess whether wastewater samples could be used for routine surveillance of NoVs, including GII.4 variants. From April 2015 to March 2016, raw sewage and effluent water samples were collected monthly from five wastewater treatment plants in SA. A total of 108 samples were screened for NoV GI and GII using real-time RT-qPCR. Overall 72.2% (78/108) of samples tested positive for NoVs with 4.6% (5/108) GI, 31.5% (34/108) GII and 36.1% (39/108) GI + GII strains being detected. Norovirus concentrations ranged from 1.02 × 10² to 3.41 × 10⁶ genome copies/litre for GI and 5.00 × 10³ to 1.31 × 10⁶ genome copies/litre for GII. Sixteen NoV genotypes (GI.2, GI.3, GI.4, GI.5, GI.6, GII.2, GII.3, GII.4, GII.7, GII.9, GII.10, GII.14, GII.16, GII.17, GII.20, and GII.21) were identified. Norovirus GII.2 and GII.17 co-dominated and the majority of GII.17 strains clustered with the novel Kawasaki 2014 variant. Sewage surveillance facilitated detection of Kawasaki 2014 in SA, which to date has not been detected with surveillance in children with gastroenteritis <5 years of age. Combined surveillance in the clinical setting and environment appears to be a valuable strategy to monitor emergence of NoV strains in countries that lack NoV outbreak surveillance.

Molecular analysis of norovirus in specimens from children enrolled in a 1982-1986 study in Belém, Brazil: A community-based longitudinal study

Fecal specimens were collected during a longitudinal, community-based study in the city of Belém, North Brazil, that was conducted over 3 years (October 1982 to March 1986), in which 20 children were included from birth to 3 years of age. A total of 229 fecal samples were screened by real time RT-PCR targeting the junction region (ORF 1/2) of the norovirus (NoV) genome. NoV-positive samples were subjected to PCR and sequencing of the viral polymerase (ORF1) and viral protein 1 (VP1) genes (ORF2). The junction region was also sequenced to assess for recombination when ORF1 and ORF2 genotyping results were dissimilar. Samples classified as GII.P4/GII.4 were further characterized by sequencing the P2 subdomain of the viral capsid to determine possible alterations. An overall positivity of 16.1% (37/229) was observed, including GI (16.2%-6/37) and GII (83.8%-31/37) genogroups. Cases of NoV reinfection in at least 2-month intervals were observed, and 12 children developed at least one case of asymptomatic NoV infection. In total, 48.6% (18/37) NoV-positive samples were subjected to nucleotide sequencing analysis targeting the following polymerase genes: GI.P3 (n = 1), GII.Pa (n = 1), GII.Pc (n = 1), GII.P4 (n = 5), GII.P6 (n = 5), GII.P7 (n = 3), GII.P12 (n = 1), and GII.P22 (n = 1). For the VP1 gene, characterization was performed in 14 (77.8%) samples: GI.3 (n = 1), GII.2 (n = 1), GII.4 (n = 4), GII.6 (n = 4), GII.7 (n = 1), GII.12 (n = 1), GII.14 (n = 1), and GII.23 (n = 1). Recombination events were confirmed in three cases (GII.P12/GII.2, GII.P7/GII.14, and GII.Pa/GII.12), and four samples genotyped as GII.P4/GII.4 were analyzed to identify variants. None had contemporary counterparts. Three children developed consecutive NoV infections by different genotypes. The present report documents the importance of NoV as a cause of childhood infection during a longitudinal study conducted more than 30 years ago.

Genotype diversity and molecular evolution of noroviruses: A 30-year (1982-2011) comprehensive study with children from Northern Brazil

A chronologically comprehensive 30-year study was conducted that involved children living in Belém, in the Amazon region of Northern Brazil, who participated in eight different studies from October 1982 to April 2011. The children were followed either in the community or in health units and hospitals in order to identify the norovirus genotypes involved in infections during this time. A total of 2,520 fecal specimens were obtained and subjected to RT-PCR and nucleotide sequencing for regions A, B, C, D and P2 of the viral genome. An overall positivity of 16.9% (n = 426) was observed, and 49% of the positive samples were genotyped (208/426), evidencing the presence of several genotypes as follows: Polymerase gene (GI.P4, GII.Pa, GII.Pc, GII.Pe, GII.Pg, GII.Pj, GII.P3, GII.P4, GII.P6, GII.P7, GII.P8, GII.P12, GII.P13, GII.P14, GII.P21, GII.P22), and VP1 gene (GI.3, GI.7, GII.1, GII.2, GII.3, GII.4, GII.6, GII.7, GII.8, GII.10, GII.12, GII.14, GII.17, GII.23). The GII.P4/GII.4 genotype determined by both open reading frames (ORFs) (partial polymerase and VP1 genes) was found for 83 samples, and analyses of the subdomain P2 region showed 10 different variants: CHDC (1970s), Tokyo (1980s), Bristol_1993, US_95/96, Kaiso_2003, Asia_2003, Hunter_2004, Yerseke_2006a, Den Haag_2006b (subcluster “O”) and New Orleans_2009. Recombination events were confirmed in 47.6% (n = 20) of the 42 samples with divergent genotyping by ORF1 and ORF2 and with probable different breakpoints within the viral genome. The evolutionary analyses estimated a rate of evolution of 1.02 x 10⁻² and 9.05 x 10⁻³ subs./site/year using regions C and D from the VP1 gene, respectively. The present research shows the broad genetic diversity of the norovirus that infected children for 30 years in Belém. These findings contribute to our understanding of noroviruses molecular epidemiology and viral evolution and provide a baseline for vaccine design.

Environmental Surveillance of Norovirus Genogroups I and II for Sensitive Detection of Epidemic Variants

Sewage samples have been investigated to study the norovirus concentrations in sewage or the genotypes of noroviruses circulating in human populations. However, the statistical relationship between the concentration of the virus and the number of infected individuals and the clinical importance of genotypes or strains detected in sewage are unclear. In this study, we carried out both environmental and clinical surveillance of noroviruses for 3 years, 2013 to 2016. We performed cross-correlation analysis of the concentrations of norovirus GI or GII in sewage samples collected weekly and the reported number of gastroenteritis cases. Norovirus genotypes in sewage were also analyzed by pyrosequencing and compared with those identified in stool samples. The cross-correlation analysis found the peak coefficient (R = 0.51) at a lag of zero, indicating that the variation in the GII concentration, expressed as the log₁₀ number of copies per milliliter, was coincident with that in the gastroenteritis cases. A total of 15 norovirus genotypes and up to 8 genotypes per sample were detected in sewage, which included all of the 13 genotypes identified in the stool samples except 2. GII.4 was most frequently detected in both sample types, followed by GII.17. Phylogenetic analysis revealed that a strain belonging to the GII.17 Kawasaki 2014 lineage had been introduced into the study area in the 2012-2013 season. An increase in GI.3 cases was observed in the 2015-2016 season, and sewage monitoring identified the presence of GI.3 in the previous season (2014-2015). Our results demonstrated that monitoring of noroviruses in sewage is useful for sensitive detection of epidemic variants in human populations.IMPORTANCE We obtained statistical evidence of the relationship between the variation in the norovirus GII concentration in sewage and that of gastroenteritis cases during the 3-year study period. Sewage sample analysis by a pyrosequencing approach enabled us to understand the temporal variation in the norovirus genotypes circulating in human populations. We found that a strain closely related to the GII.17 Kawasaki 2014 lineage had been introduced into the study area at least 1 year before its appearance and identification in clinical cases. A similar pattern was observed for GI.3; cases were reported in the 2015-2016 season, and closely related strains were found in sewage in the previous season. Our observation indicates that monitoring of noroviruses in sewage is useful for the rapid detection of an epidemic and is also sensitive enough to study the molecular epidemiology of noroviruses. Applying this approach to other enteric pathogens in sewage will enhance our understanding of their ecology.

Norovirus genogroups I and II in environmental water samples from Belém city, Northern Brazil

This study investigated the presence of norovirus (NoV) GI and GII in environmental samples from the northern region of Brazil. Water samples were collected monthly (November 2008/October 2010) from different sources and sewage and concentrated by the adsorption-elution method. The NoV investigation used molecular methods followed by sequencing reactions. The general positivity for NoV was 33.9% (57/168). Considering the results obtained only in the semi-nested RT-PCR (reverse transcription polymerase chain reaction) and only in the TaqMan^® real-time PCR, the rates were 26.8% (45/168) and 27.4% (46/168), respectively, being for NoV GI 22.2% (10/45) and 19.6% (9/46); for GII 17.8% (8/45) and 15.2% (7/46); and for GI + GII 60% (27/45) and 65.2% (30/46), respectively. Different GI (GI.1, GI.4, GI.7 and GI.8) and GII (GII.4, GII.6, GII.9, GII.12 and GII.14) genotypes were detected. These results demonstrated the NoV was disseminated in the waters of Belém city due to a lack of sanitation that allowed the discharge of contaminated effluents into these aquatic ecosystems.

Human polyomavirus: Advantages and limitations as a human-specific viral marker in aquatic environments

Human polyomaviruses (HPyVs) cause persistent infections in organs such as kidney, brain, skin, liver, respiratory tract, etc., and some types of HPyV are constantly excreted in the urine and/or feces of infected and healthy individuals. The use of an enteric virus as an indicator for human sewage/waste contamination in aquatic environments has been proposed; HPyVs are a good candidate since they are routinely found in environmental water samples from different geographical areas with relatively high abundance. HPyVs are highly human specific, having been detected in human waste from all age ranges and undetected in animal waste samples. In addition, HPyVs show a certain degree of resistance to high temperature, chlorine, UV, and low pH, with molecular signals (i.e., DNA) persisting in water for several months. Recently, various concentration methods (electronegative/positive filtration, ultrafiltration, skim-milk flocculation) and detection methods (immunofluorescence assay, cell culture, polymerase chain reaction (PCR), integrated cell culture PCR (ICC-PCR), and quantitative PCR) have been developed and demonstrated for HPyV, which has enabled the identification and quantification of HPyV in various environmental samples, such as sewage, surface water, seawater, drinking water, and shellfish. In this paper, we summarize these recent advancements in detection methods and the accumulation of environmental surveillance and laboratory-scale experiment data, and discuss the potential advantages as well as limitations of HPyV as a human-specific viral marker in aquatic environments.

Comparative Evaluation of Real-Time PCR Methods for Human Noroviruses in Wastewater and Human Stool

Selecting the best quantitative PCR assay is essential to detect human norovirus genome effectively from clinical and environmental samples because no cell lines have been developed to propagate this virus. The real-time PCR methods for noroviruses GI (4 assays) and GII (3 assays) were evaluated using wastewater (n = 70) and norovirus-positive stool (n = 77) samples collected in Japan between 2012 and 2013. Standard quantitative PCR assays recommended by the U.S. Environmental Protection Agency, International Organization for Standardization, and Ministry of Health, Labour and Welfare, Japan, together with recently reported assays were included. Significant differences in positive rates and quantification cycles were observed by non-parametric analysis. The present study identifies the best assay for norovirus GI and GII to amplify norovirus genomes efficiently.

Temporal dynamics of norovirus determined through monitoring of municipal wastewater by pyrosequencing and virological surveillance of gastroenteritis cases

Norovirus is a leading etiological agent of viral gastroenteritis. Because of relatively mild disease symptoms and frequent asymptomatic infections, information on the ecology of this virus is limited. Our objective was to examine the genetic diversity of norovirus circulating in the human population by means of genotyping the virus in municipal wastewater. We investigated norovirus genogroups I and II (GI and GII) in municipal wastewater in Japan by pyrosequencing and quantitative PCR (qPCR) from November 2012 to March 2013. Virological surveillance for gastroenteritis cases was concurrently conducted in the same area. A total of fourteen distinct genotypes in total (GI.1, 3, 4, 6, 7, GII.2, 4, 5, 6, 7, 12, 13, 14, and 17), with up to eight genotypes detected per sample, were observed in wastewater using pyrosequencing; only four genotypes (GI.6, GII.4, 5, and 14) were obtained from clinical samples. Seventy-eight percent of norovirus-positive stool samples contained GII.4, but this genotype was not dominant in wastewater. The norovirus GII.4 Sydney 2012 variant, which appeared and spread during our study period, was detected in both the wastewater and clinical samples. These results suggest that an environmental approach using pyrosequencing yields a more detailed distribution of norovirus genotypes/variants. Thus, wastewater monitoring by pyrosequencing is expected to provide an effective analysis of the distribution of norovirus genotypes causing symptomatic and asymptomatic infections in human populations.

Fecal pollution source tracking toolbox for identification, evaluation and characterization of fecal contamination in receiving urban surface waters and groundwater

The quality of surface waters/groundwater of a geographical region can be affected by anthropogenic activities, land use patterns and fecal pollution sources from humans and animals. Therefore, the development of an efficient fecal pollution source tracking toolbox for identifying the origin of the fecal pollution sources in surface waters/groundwater is especially helpful for improving management efforts and remediation actions of water resources in a more cost-effective and efficient manner. This review summarizes the updated knowledge on the use of fecal pollution source tracking markers for detecting, evaluating and characterizing fecal pollution sources in receiving surface waters and groundwater. The suitability of using chemical markers (i.e. fecal sterols, fluorescent whitening agents, pharmaceuticals and personal care products, and artificial sweeteners) and/or microbial markers (e.g. F+RNA coliphages, enteric viruses, and host-specific anaerobic bacterial 16S rDNA genetic markers) for tracking fecal pollution sources in receiving water bodies is discussed. In addition, this review also provides a comprehensive approach, which is based on the detection ratios (DR), detection frequencies (DF), and fate of potential microbial and chemical markers. DR and DF are considered as the key criteria for selecting appropriate markers for identifying and evaluating the impacts of fecal contamination in surface waters/groundwater.

Pathogenic Enteric Viruses and Microbial Indicators during Secondary Treatment of Municipal Wastewater

Pathogenic enteric viruses are responsible for a wide range of infections in humans, with diverse symptoms. Raw and partially treated wastewaters are major sources of environmental contamination with enteric viruses. We monitored a municipal secondary wastewater treatment plant (New Orleans, LA) on a monthly basis for norovirus (NoV) GI and GII and enterovirus serotypes using multiplex reverse transcription-quantitative PCR (RT-qPCR) and microbial indicators of fecal contamination using standard plating methods. Densities of indicator bacteria (enterococci, fecal coliforms, and Escherichia coli) did not show monthly or seasonal patterns. Norovirus GII was more abundant than GI and, along with enterovirus serotypes, increased in influent during fall and spring. The highest NoV GI density in influent was in the fall, reaching an average of 4.0 log10 genomic copies/100 ml. Norovirus GI removal (0.95 log10) was lower than that for GII, enterovirus serotypes, and male-specific coliphages (1.48 log10) or for indicator bacteria (4.36 log10), suggesting higher resistance of viruses to treatment. Male-specific coliphages correlated with NoV GII densities in influent and effluent (r = 0.48 and 0.76, respectively) and monthly removal, indicating that male-specific coliphages can be more reliable than indicator bacteria to monitor norovirus GII load and microbial removal. Dominant norovirus genotypes were classified into three GI genotypes (GI.1, GI.3, and GI.4) and four GII genotypes (GII.3, GII.4, GII.13, and GII.21), dominated by GI.1 and GII.4 strains. Some of the seasonal and temporal patterns we observed in the pathogenic enteric viruses were different from those of epidemiological observations.

Evidence of viral dissemination and seasonality in a Mediterranean river catchment: Implications for water pollution management

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.

Deciphering the Diversities of Astroviruses and Noroviruses in Wastewater Treatment Plant Effluents by a High-Throughput Sequencing Method

Although clinical epidemiology lists human enteric viruses to be among the primary causes of acute gastroenteritis in the human population, their circulation in the environment remains poorly investigated. These viruses are excreted by the human population into sewers and may be released into rivers through the effluents of wastewater treatment plants (WWTPs). In order to evaluate the viral diversity and loads in WWTP effluents of the Paris, France, urban area, which includes about 9 million inhabitants (approximately 15% of the French population), the seasonal occurrence of astroviruses and noroviruses in 100 WWTP effluent samples was investigated over 1 year. The coupling of these measurements with a high-throughput sequencing approach allowed the specific estimation of the diversity of human astroviruses (human astrovirus genotype 1 [HAstV-1], HAstV-2, HAstV-5, and HAstV-6), 7 genotypes of noroviruses (NoVs) of genogroup I (NoV GI.1 to NoV GI.6 and NoV GI.8), and 16 genotypes of NoVs of genogroup II (NoV GII.1 to NoV GII.7, NoV GII.9, NoV GII.12 to NoV GII.17, NoV GII.20, and NoV GII.21) in effluent samples. Comparison of the viral diversity in WWTP effluents to the viral diversity found by analysis of clinical data obtained throughout France underlined the consistency between the identified genotypes. However, some genotypes were locally present in effluents and were not found in the analysis of the clinical data. These findings could highlight an underestimation of the diversity of enteric viruses circulating in the human population. Consequently, analysis of WWTP effluents could allow the exploration of viral diversity not only in environmental waters but also in a human population linked to a sewerage network in order to better comprehend viral epidemiology and to forecast seasonal outbreaks.

Large scale survey of enteric viruses in river and waste water underlines the health status of the local population

Although enteric viruses constitute a major cause of acute waterborne diseases worldwide, environmental data about occurrence and viral load of enteric viruses in water are not often available. In this study, enteric viruses (i.e., adenovirus, aichivirus, astrovirus, cosavirus, enterovirus, hepatitis A and E viruses, norovirus of genogroups I and II, rotavirus A and salivirus) were monitored in the Seine River and the origin of contamination was untangled. A total of 275 water samples were collected, twice a month for one year, from the river Seine, its tributaries and the major WWTP effluents in the Paris agglomeration. All water samples were negative for hepatitis A and E viruses. AdV, NVGI, NVGII and RV-A were the most prevalent and abundant populations in all water samples. The viral load and the detection frequency increased significantly between the samples collected the most upstream and the most downstream of the Paris urban area. The calculated viral fluxes demonstrated clearly the measurable impact of WWTP effluents on the viral contamination of the Seine River. The viral load was seasonal for almost all enteric viruses, in accordance with the gastroenteritis recordings provided by the French medical authorities. These results implied the existence of a close relationship between the health status of inhabitants and the viral contamination of WWTP effluents and consequently surface water contamination. Subsequently, the regular analysis of wastewater could serve as a proxy for the monitoring of the human viruses circulating in both a population and surface water.

Fractional poisson--a simple dose-response model for human norovirus

This study utilizes old and new Norovirus (NoV) human challenge data to model the dose-response relationship for human NoV infection. The combined data set is used to update estimates from a previously published beta-Poisson dose-response model that includes parameters for virus aggregation and for a beta-distribution that describes variable susceptibility among hosts. The quality of the beta-Poisson model is examined and a simpler model is proposed. The new model (fractional Poisson) characterizes hosts as either perfectly susceptible or perfectly immune, requiring a single parameter (the fraction of perfectly susceptible hosts) in place of the two-parameter beta-distribution. A second parameter is included to account for virus aggregation in the same fashion as it is added to the beta-Poisson model. Infection probability is simply the product of the probability of nonzero exposure (at least one virus or aggregate is ingested) and the fraction of susceptible hosts. The model is computationally simple and appears to be well suited to the data from the NoV human challenge studies. The model's deviance is similar to that of the beta-Poisson, but with one parameter, rather than two. As a result, the Akaike information criterion favors the fractional Poisson over the beta-Poisson model. At low, environmentally relevant exposure levels (<100), estimation error is small for the fractional Poisson model; however, caution is advised because no subjects were challenged at such a low dose. New low-dose data would be of great value to further clarify the NoV dose-response relationship and to support improved risk assessment for environmentally relevant exposures.

Assessment of gastroenteric viruses from wastewater directly discharged into Uruguay River, Uruguay

The aim of this study was to assess the viral contamination of group A rotavirus (RVA), norovirus (NoV), and human astrovirus (HAstV) in sewage directly discharged into Uruguay River and to characterize RVA genotypes circulating in Uruguay. For this purpose, sewage samples (n = 96) were collected biweekly from March 2011 to February 2012 in four Uruguayan cities: Bella Unión, Salto, Paysandú, and Fray Bentos. Each sample was concentrated by ultracentrifugation method. Qualitative and quantitative RT-PCR for RVA, NoV, and HAstV were performed. A wide dissemination of gastroenteric viruses was observed in the sewage samples analyzed with 80% of positivity, being NoV (51%) the most frequently detected followed by RVA with a frequency of 49% and HAstV with 45%. Genotypes of RVA were typed using multiplex semi-nested RT-PCR as follows: P[8] (n = 15), P[4] (n = 8), P[10] (n = 1), P[11] (n = 1), G2 (n = 29), and G3 (n = 2). The viral load ranged from 10(3) to 10(7) genomic copies/liter, and they were detected roughly with the same frequency in all participant cities. A peak of RVA and HAstV detection was observed in colder months (June to September), whereas no seasonality was observed for NoV. This study demonstrates for the first time, the high degree of gastroenteric viral contamination in the country; highlighting the importance of developing these analyses as a tool to determine the viral contamination in this hydrographic boundary region used by the local populations for recreation and consumption, establishing an elevated risk of gastroenteric diseases for human health.

Detection of norovirus genogroup IV, klassevirus, and pepper mild mottle virus in sewage samples in South Korea

Norovirus (NoV) genogroup (G) IV has been infrequently isolated from patients suffering from acute gastroenteritis (AGE), although this virus has not been detected in Korea. Klassevirus, a novel virus belonging to the family Picornaviridae and a possible etiologic agent of AGE, and pepper mild mottle virus (PMMoV), which originates from processed pepper products and is shed in human feces, are suggested to be new indicators of fecal pollution. We aimed to investigate the presence of NoV-GIV, klassevirus, and PMMoV in sewage samples collected in Korea. Between December 2010 and February 2012, influent sewage samples were collected every month from a wastewater treatment plant located in the eastern part of Seoul in Korea. The sewage samples were concentrated by the adsorption elution method using an HA (pore size of 0.45 μm with mixed cellulose ester) electronegative filter with an acid-rinse procedure. RT-PCR was performed using specific primers for the capsid gene of NoV-GII and NoV-GIV, the coat gene of PMMoV, and the VP0/VP1 gene of klassevirus. Among the 14 sewage samples tested, klassevirus was detected in eight (57.1 %), PMMoV in eight (57.1 %), NoV-GII in five (35.7 %), and NoV-GIV in three (21.4 %). NoV-GIV was detected in December 2010 and January and March 2011. PMMoV and klassevirus were frequently detected in winter. Phylogenetic analysis revealed that the NoV-GIV detected in this study belonged to G-IV1 lineage. This is the first study to confirm the presence of NoV-GIV, klassevirus, and PMMoV in sewage samples in Korea.

Development of a reverse transcription-quantitative PCR system for detection and genotyping of aichi viruses in clinical and environmental samples

Aichi viruses (AiVs) have been proposed as a causative agent of human gastroenteritis potentially transmitted by fecal-oral routes through contaminated food or water. In the present study, we developed a TaqMan minor groove binder (MGB)-based reverse transcription-quantitative PCR (RT-qPCR) system that is able to quantify AiVs and differentiate between genotypes A and B. This system consists of two assays, an AiV universal assay utilizing a universal primer pair and a universal probe and a duplex genotype-specific assay utilizing the same primer pair and two genotype-specific probes. The primers and probes were designed based on multiple alignments of the 21 available AiV genome sequences containing the capsid gene. Using a 10-fold dilution of plasmid DNA containing the target sequences, it was confirmed that both assays allow detection and quantification of AiVs with a quantitative range of 1.0 × 10(1) to 1.0 × 10(7) copies/reaction, and the genotype-specific assay reacts specifically to each genotype. To validate the newly developed assays, 30 clinical stool specimens were subsequently examined with the assays, and the AiV RNA loads were determined to be 1.4 × 10(4) to 6.6 × 10(9) copies/g stool. We also examined 12 influent and 12 effluent wastewater samples collected monthly for a 1-year period to validate the applicability of the assays for detection of AiVs in environmental samples. The AiV RNA concentrations in influent and effluent wastewater were determined to be up to 2.2 × 10(7) and 1.8 × 10(4) copies/liter, respectively. Our RT-qPCR system is useful for routine diagnosis of AiVs in clinical stool specimens and environmental samples.

Human calicivirus diversity in wastewater in South Africa

AIM

To investigate the diversity of human caliciviruses (HuCVs) in wastewater from small- to medium-sized communities in five provinces of South Africa (SA).

METHODS AND RESULTS

Wastewater samples (51) were screened for norovirus (NoV) GI, GII, GIV and sapovirus (SaV) using real-time reverse transcription (RT)-PCR. Partial capsid nucleotide sequences were analysed for genotyping. At least one HuCV was detected in 42 samples (82%) with NoV GI being detected in 15 (29%), NoV GII in 32 (63%) and SaV in 37 (73%) samples. NoV GIV was not detected. Five NoV GI genotypes (GI.1, GI.3, GI.4, GI.8 and GI.unassigned), eight NoV GII genotypes (GII.2, GII.3, GII.4, GII.6, GII.7, GII.12, GII.13 and GII.17) and six SaV genotypes (GI.2, GI.3, GI.6, GI.7, GII.1 and GII.2) were characterized.

CONCLUSIONS

Many NoV and SaV genotypes were detected in wastewater, demonstrating a high genetic diversity of HuCVs in the surrounding communities. Caliciviruses were characterized from several provinces in SA, indicating widespread occurrence in the country.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides valuable new data on CVs circulating in SA, including the first data on SaV strains from wastewater in Africa. Environmental surveillance is especially important in countries like SA where outbreak reporting systems or routine HuCV surveillance is lacking.

Prevalence and genetic diversity of klassevirus in wastewater in Japan

Klassevirus is a novel virus belonging to the family Picornaviridae. This study examined the prevalence and genetic diversity of klassevirus in wastewater. Raw sewage (100 ml) and secondary-treated sewage (2 l) were collected monthly for 14 months between January 2011 and February 2012 from a wastewater treatment plant in Japan. Klassevirus in the sample was concentrated by the electronegative membrane-vortex method, followed by qualitative detection by means of three types of reverse transcription (RT)-nested polymerase chain reactions (PCRs). Klassevirus was detected in seven of the 14 raw sewage (50 %) and four of the 14 secondary-treated sewage (29 %) samples by the RT-nested PCRs targeting the 2C and/or 3D regions. In contrast, none of the samples tested positive for the virus by the RT-nested PCR targeting the VP0/VP3 region. Based on direct nucleotide sequence analysis of the klassevirus-positive nested PCR fragments, the tested samples showed high nucleotide sequence similarities of 94.7-100.0 % and 93.2-100.0 % in the 2C and 3D regions, respectively, indicating the presence of a single klassevirus strain. To our knowledge, this is the first study evaluating seasonal prevalence and genetic diversity of klassevirus in environmental waters.