Hiding in Plain Sight? It's Time to Investigate Other Possible Transmission Routes for Hepatitis E Virus (HEV) in Developed Countries

Historically in developed countries, reported hepatitis E cases were typically travellers returning from countries where hepatitis E virus (HEV) is endemic, but now there are increasing numbers of non-travel-related ("autochthonous") cases being reported. Data for HEV in New Zealand remain limited and the transmission routes unproven. We critically reviewed the scientific evidence supporting HEV transmission routes in other developed countries to inform how people in New Zealand may be exposed to this virus. A substantial body of indirect evidence shows domesticated pigs are a source of zoonotic human HEV infection, but there is an information bias towards this established reservoir. The increasing range of animals in which HEV has been detected makes it important to consider other possible animal reservoirs of HEV genotypes that can or could infect humans. Foodborne transmission of HEV from swine and deer products has been proven, and a large body of indirect evidence (e.g. food surveys, epidemiological studies and phylogenetic analyses) support pig products as vehicles of HEV infection. Scarce data from other foods suggest we are neglecting other potential sources of foodborne HEV infection. Moreover, other transmission routes are scarcely investigated in developed countries; the role of infected food handlers, person-to-person transmission via the faecal-oral route, and waterborne transmission from recreational contact or drinking untreated or inadequately treated water. People have become symptomatic after receiving transfusions of HEV-contaminated blood, but it is unclear how important this is in the overall hepatitis E disease burden. There is need for broader research efforts to support establishing risk-based controls.

Effect of μM Fe addition, mild heat and solar UV on sulfate radical-mediated inactivation of bacteria, viruses, and micropollutant degradation in water

In this work, solar disinfection (SODIS) was enhanced by moderate addition of Fe and sodium peroxydisulfate (PDS), under solar light. A systematic assessment of the activating factors was performed, firstly isolated, then in pairs and concluded in the combined Fe/heat/solar UV-PDS activation process. Solar light was the most effective (single) activator, and its combination with Fe and heat (double activation) yielded high level of synergies (up to S = 2.13). The triple activation was able to reduce the bacterial load up to 6-log in less than 1 h, similarly to the photo-Fenton process done in comparison (SODIS alone: >5 h). Fe-oxides were suitable activators of PDS under the same conditions while the presence of organic matter enhanced bacterial inactivation by the triple activated PDS process. The degradation of a (selected) mixture of micropollutants (i.e. drugs, pesticides) was also achieved in similar order of magnitude, and faster than the photo-Fenton process. Finally, the removal of a viral pathogen indicator (MS2 bacteriophage) was attained at minute-range residence times. The aforementioned facts indicate the suitability of the mild, combined process, as a potential SODIS enhancement, producing safe drinking water for sunny and especially for developing countries.

Evaluation of Bacterial Contamination as an Indicator of Viral Contamination in a Sedimentary Aquifer in Uruguay

In Uruguay, groundwater is frequently used for agricultural activities, as well as for human consumption in urban and rural areas. As in many countries worldwide, drinking water microbiological quality is evaluated only according to bacteriological standards and virological analyses are not mentioned in the legislation. In this work, the incidence of human viral (Rotavirus A, Norovirus GII, and human Adenovirus) and bacterial (total and thermotolerant coliform and Pseudomonas aeruginosa) contamination in groundwater in the Salto district, Uruguay, as well as the possible correlation between these groups of microorganisms, was studied. From a total of 134 groundwater samples, 42 (32.1%) were positive for Rotavirus, only 1 (0.7%) for both Rotavirus and Adenovirus, and 96 (72.6%) samples were positive for bacterial indicators. Results also show that Rotavirus presence was not associated with changes in chemical composition of the aquifer water. Bacteriological indicators were not adequate to predict the presence of viruses in individual groundwater samples (well scale), but a deeper spatial-temporal analysis showed that they are promising candidates to assess the viral contamination degree at aquifer scale, since from the number of wells with bacterial contamination the number of wells with viral contamination could be estimated.

A gastroenteritis outbreak associated with drinking water in a college in northwest China

An acute gastroenteritis outbreak occurred at a private college in June 2014 in northwest China. This outbreak involved two teachers and 629 students (range: 17-27 years, average 21.3 years). The main symptoms included non-bloody watery diarrhea, stomach ache, nausea, and vomiting, and the duration of illness ranged from 1 to 7 days. Eight of 18 water samples were disqualified. Thirty-four norovirus (NoV) RNA-positive samples were identified from 48 stool-related samples (genotyping results: 13 GII, 13 GI and 8 GI + GII mixture). Fourteen NoV samples were successfully characterized for genotype, including two GII.6, five GI.6, four GI.3, and three GI.1. Enteropathogenic Escherichia coli (EPEC) and enteroadherent Escherichia coli (EAEC) DNA was detected from patient stool specimens and water samples from well one; two EAEC strains and one EPEC strain were isolated from patient stool specimens. The risk ratios (RRs) associated with wells one and two were 1.66 and 1.49, respectively, and the RR associated with living in north dormitory building one was 2.59. The patients' epidemiological characteristics, symptoms, and duration of illness indicated that NoV-contaminated water might be the origin of this outbreak, and RR analysis suggested that the two wells were linked to the outbreak.

Coagulant residues' influence on virus enumeration as shown in a study on virus removal using aluminium, zirconium and chitosan

Research on microorganism reduction by physicochemical water treatment is often carried out under the assumption that the microbiological enumeration techniques are not affected by the presence of coagulants. Data presented here indicate that bacteriophage enumeration by plaque assay and RT-qPCR (reverse transcription quantitative polymerase chain reaction) can be affected by these water treatment chemicals. Treatment of water samples with an alkaline protein-rich solution prior to plaque assay and optimization of RNA extraction for RT-qPCR were implemented to minimize the interference. The improved procedures were used in order to investigate reduction of three viral pathogens and the MS2 model virus in the presence of three coagulants. A conventional aluminium coagulant was compared to alternative agents (zirconium and chitosan) in a coagulation-filtration system. The highest virus reduction, i.e., 99.9-99.99%, was provided by chitosan, while aluminium and zirconium reduced virus by 99.9% in colour-rich water and by 90% in water with less colour, implying an effect of coagulant type and raw water quality on virus reduction. Although charge characteristics of viruses were associated with virus reduction, the results reveal that the MS2 phage is a suitable model for aggregation and retention of the selected pathogens.

Norovirus in Bottled Water Associated with Gastroenteritis Outbreak, Spain, 2016

In April 2016, an outbreak of gastrointestinal illness (4,136 cases) occurred in Catalonia, Spain. We detected high levels of norovirus genotypes I and II in office water coolers associated with the outbreak. Infectious viral titer estimates were 33–49 genome copies/L for genotype I and 327–660 genome copies/L for genotype II.

Pepper mild mottle virus as a process indicator at drinking water treatment plants employing coagulation-sedimentation, rapid sand filtration, ozonation, and biological activated carbon treatments in Japan

To assess the potential of pepper mild mottle virus (PMMoV) as a viral process indicator, its reduction through coagulation-sedimentation (CS) and rapid sand filtration (RSF) were compared with those of Escherichia coli, previously used viral indicators, and norovirus genotype II (NoV GII; enteric virus reference pathogen) in a bench-scale experiment. PMMoV log₁₀ reductions in CS (1.96 ± 0.30) and RSF (0.26 ± 0.38) were similar to those of NoV GII (1.86 ± 0.61 and 0.28 ± 0.46). PMMoV, the most abundant viruses in the raw water, was also determined during CS, RSF, and advanced treatment processes at two full-scale drinking water treatment plants under strict turbidity management over a 13-month period. PMMoV was concentrated from large-volume water samples (10-614 L) and quantified by Taqman-based quantitative polymerase chain reaction. The PMMoV log₁₀ reduction in CS (2.38 ± 0.74, n = 13 and 2.63 ± 0.76, n = 10 each for Plant A and B) and in ozonation (1.91 ± 1.18, n = 5, Plant A) greatly contributed to the overall log₁₀ reduction. Our results suggest that PMMoV can act as a useful treatment process indicator of enteric viruses and can be used to monitor the log₁₀ reduction of individual treatment processes at drinking water treatment plants due to its high and consistent copy numbers in source water.

Estimating virus occurrence using Bayesian modeling in multiple drinking water systems of the United States

Drinking water treatment plants rely on purification of contaminated source waters to provide communities with potable water. One group of possible contaminants are enteric viruses. Measurement of viral quantities in environmental water systems are often performed using polymerase chain reaction (PCR) or quantitative PCR (qPCR). However, true values may be underestimated due to challenges involved in a multi-step viral concentration process and due to PCR inhibition. In this study, water samples were concentrated from 25 drinking water treatment plants (DWTPs) across the US to study the occurrence of enteric viruses in source water and removal after treatment. The five different types of viruses studied were adenovirus, norovirus GI, norovirus GII, enterovirus, and polyomavirus. Quantitative PCR was performed on all samples to determine presence or absence of these viruses in each sample. Ten DWTPs showed presence of one or more viruses in source water, with four DWTPs having treated drinking water testing positive. Furthermore, PCR inhibition was assessed for each sample using an exogenous amplification control, which indicated that all of the DWTP samples, including source and treated water samples, had some level of inhibition, confirming that inhibition plays an important role in PCR-based assessments of environmental samples. PCR inhibition measurements, viral recovery, and other assessments were incorporated into a Bayesian model to more accurately determine viral load in both source and treated water. Results of the Bayesian model indicated that viruses are present in source water and treated water. By using a Bayesian framework that incorporates inhibition, as well as many other parameters that affect viral detection, this study offers an approach for more accurately estimating the occurrence of viral pathogens in environmental waters.

Coxsackievirus B4 as a Causative Agent of Diabetes Mellitus Type 1: Is There a Role of Inefficiently Treated Drinking Water and Sewage in Virus Spreading?

This study proposed to detect the enterovirus (EV) infection in children with type 1 diabetes mellitus (T1D) and to assess the role of insufficiently treated water and sewage as sources of viral spreading. Three hundred and eighty-two serum specimens of children with T1D, one hundred serum specimens of children who did not suffer from T1D as control, and forty-eight water and sewage samples were screened for EV RNA using nested RT-PCR. The number of genome copies and infectious units of EVs in raw and treated sewage and water samples were investigated using real-time (RT)-PCR and plaque assay, respectively. T1D markers [Fasting blood glucose (FBG), HbA1c, and C-peptide], in addition to anti-Coxsackie A & B viruses (CVs A & B) IgG, were measured in control, T1D-negative EV (T1D-EV^-), and T1D-positive EV (T1D-EV⁺) children specimens. The prevalence of EV genome was significantly higher in diabetic children (26.2%, 100 out of 382) than the control children (0%, 0 out of 100). FBG and HbA1c in T1D-EV^- and T1D-EV⁺ children specimens were significantly higher than those in the control group, while c-peptide in T1D-EV^- and T1D-EV⁺ children specimens was significantly lower than that in the control (n = 100; p < 0.001). Positivity of anti-CVs A & B IgG was 70.7, 6.7, and 22.9% in T1D-EV⁺, T1D-EV^-, and control children specimens, respectively. The prevalence of EV genome in drinking water and treated sewage samples was 25 and 33.3%, respectively. The prevalence of EV infectious units in drinking water and treated sewage samples was 8.5 and 25%, respectively. Quantification assays were performed to assess the capabilities of both wastewater treatment plants (WWTPs) and water treatment plants (WTPs) to remove EV. The reduction of EV genome in Zenin WWTP ranged from 2 to 4 log₁₀, while the reduction of EV infectious units ranged from 1 to 4 log₁₀. The reduction of EV genome in El-Giza WTP ranged from 1 to 3 log₁₀, while the reduction of EV infectious units ranged from 1 to 2 log₁₀. This capability of reduction did not prevent the appearance of infectious EV in treated sewage and drinking water. Plaque purification was performed for isolation of separate EV isolates from treated and untreated water and sewage samples. Characterization of the EV amplicons by RT-PCR followed by sequencing of these isolates revealed high homology (97%) with human coxsackievirus B4 (CV B4) in 60% of the isolates, while the rest of the isolates belonged to poliovirus type 1 and type 2 vaccine strains. On the other hand, characterization of the EV amplicons by RT-PCR followed by sequencing for T1D-EV⁺ children specimens indicated that all samples contained CV B4 with the same sequence characterized in the environmental samples. CV B4-contaminated drinking water or treated sewage may play a role as a causative agent of T1D in children.

Persistent Norovirus Contamination of Groundwater Supplies in Two Waterborne Outbreaks

Microbiological contamination of groundwater supplies causes waterborne outbreaks worldwide. In this study, two waterborne outbreaks related to microbiological contamination of groundwater supplies are described. Analyses of pathogenic human enteric viruses (noroviruses and adenoviruses), fecal bacteria (Campylobacter spp. and Salmonella spp.), and indicator microbes (E. coli, coliform bacteria, intestinal enterococci, Clostridium perfringens, heterotrophic plate count, somatic and F-specific coliphages) were conducted in order to reveal the cause of the outbreaks and to examine the effectiveness of the implemented management measures. Moreover, the long-term persistence of noro- and adenovirus genomes was investigated. Noroviruses were detected in water samples from both outbreaks after the intrusion of wastewater into the drinking water sources. In the outbreak I, the removal efficiency of norovirus genome (3.0 log₁₀ removal) in the sand filter of onsite wastewater treatment system (OWTS) and during the transport through the soil into the groundwater well was lower than the removal efficiencies of E. coli, coliform bacteria, intestinal enterococci, and spores of C. perfringens (6.2, 6.0, > 5.9, and > 4.8 log₁₀ removals, respectively). In the outbreak II, cleaning of massively contaminated groundwater well and drinking water distribution network proved challenging, and noro- and adenovirus genomes were detected up to 3 months (108 days). The long-term persistence study showed that noro- and adenovirus genomes can remain detectable in the contaminated water samples up to 1277 and 1343 days, respectively. This study highlights the transport and survival properties of enteric viruses in the environment explaining their potency to cause waterborne outbreaks.

Evaluation of the suitability of a plant virus, pepper mild mottle virus, as a surrogate of human enteric viruses for assessment of the efficacy of coagulation-rapid sand filtration to remove those viruses

Here, we evaluated the removal of three representative human enteric viruses - adenovirus (AdV) type 40, coxsackievirus (CV) B5, and hepatitis A virus (HAV) IB - and one surrogate of human caliciviruses - murine norovirus (MNV) type 1 - by coagulation-rapid sand filtration, using water samples from eight water sources for drinking water treatment plants in Japan. The removal ratios of a plant virus (pepper mild mottle virus; PMMoV) and two bacteriophages (MS2 and φX174) were compared with the removal ratios of human enteric viruses to assess the suitability of PMMoV, MS2, and φX174 as surrogates for human enteric viruses. The removal ratios of AdV, CV, HAV, and MNV, evaluated via the real-time polymerase chain reaction (PCR) method, were 0.8-2.5-log₁₀ when commercially available polyaluminum chloride (PACl, basicity 1.5) and virgin silica sand were used as the coagulant and filter medium, respectively. The type of coagulant affected the virus removal efficiency, but the age of silica sand used in the rapid sand filtration did not. Coagulation-rapid sand filtration with non-sulfated, high-basicity PACls (basicity 2.1 or 2.5) removed viruses more efficiently than the other aluminum-based coagulants. The removal ratios of MS2 were sometimes higher than those of the three human enteric viruses and MNV, whereas the removal ratios of φX174 tended to be smaller than those of the three human enteric viruses and MNV. In contrast, the removal ratios of PMMoV were similar to and strongly correlated with those of the three human enteric viruses and MNV. Thus, PMMoV appears to be a suitable surrogate for human enteric viruses for the assessment of the efficacy of coagulation-rapid sand filtration to remove viruses.

Quantitative microbial risk assessment to estimate the health risk from exposure to noroviruses in polluted surface water in South Africa

This study assessed the risks posed by noroviruses (NoVs) in surface water used for drinking, domestic, and recreational purposes in South Africa (SA), using a quantitative microbial risk assessment (QMRA) methodology that took a probabilistic approach coupling an exposure assessment with four dose-response models to account for uncertainty. Water samples from three rivers were found to be contaminated with NoV GI (80-1,900 gc/L) and GII (420-9,760 gc/L) leading to risk estimates that were lower for GI than GII. The volume of water consumed and the probabilities of infection were lower for domestic (2.91 × 10^-8 to 5.19 × 10^-1) than drinking water exposures (1.04 × 10^-5 to 7.24 × 10^-1). The annual probabilities of illness varied depending on the type of recreational water exposure with boating (3.91 × 10^-6 to 5.43 × 10^-1) and swimming (6.20 × 10^-6 to 6.42 × 10^-1) being slightly greater than playing next to/in the river (5.30 × 10^-7 to 5.48 × 10^-1). The QMRA was sensitive to the choice of dose-response model. The risk of NoV infection or illness from contaminated surface water is extremely high in SA, especially for lower socioeconomic individuals, but is similar to reported risks from limited international studies.

Removal of model viruses, E. coli and Cryptosporidium oocysts from surface water by zirconium and chitosan coagulants

The present work evaluates the effect of contact filtration, preceded by coagulation with zirconium (Zr) and chitosan coagulants, on model microorganisms and waterborne pathogens. River water intended for potable water production was spiked with MS2 and Salmonella Typhimurium 28B bacteriophages, Escherichia coli, and Cryptosporidium parvum oocysts prior to coagulation. The hygienic performance demonstrated by Zr comprised 3.0-4.0 log₁₀ removal of viruses and 5.0-6.0 log₁₀ removal of E. coli and C. parvum oocysts. Treatment with chitosan resulted in a removal of 2.5-3.0 log₁₀ of viruses and parasites, and 4.5-5.0 log₁₀ of bacteria. A reference coagulant, polyaluminium chloride (PACl), gave a 2.5-3.0 log₁₀ removal of viruses and 4.5 log₁₀ of E. coli. These results indicate that both Zr and chitosan enable adequate removal of microorganisms from surface water. The present study also attempts to assess removal rates of the selected microorganisms with regard to their size and surface properties. The isoelectric point of the Salmonella Typhimurium 28B bacteriophage is reported for the first time. The retention of the selected microorganisms in the filter bed appeared to have some correlation with their size, but the effect of the charge remained unclear.

New technique for direct fluoroimmunomagnetic detection of rotavirus in water samples

A new rapid, sensitive and selective method for rotavirus detection in water samples is described in this paper. Amino pink magnetic microparticles were functionalized with monoclonal antibodies and used to capture, concentrate, separate and detect infectious rotavirus particles in distilled and drinking water samples. The fluorescence of the microparticles was used to determine the presumptive presence of rotaviruses by using confocal microscopy. Atomic force microscopy and transmission electron microscopy were used to confirm the presence of the anti-rotavirus antibodies attached to the surface of the magnetic microparticles as well as that of viruses attached through the antibody. In addition, RNA extraction, quantification and amplification were carried out to validate the microscopic observations. The selectivity of the microparticles was tested in a sample containing a mix of enteric viruses. It was concluded that functionalizing fluoromagnetic microparticles with anti-rotavirus monoclonal antibodies constituted a fast, simple and reliable technique for detecting as low as 10 Rotavirus particles in 1 L of artificial or real water in just 2 hours.

Effect of APOE ε4 allele on survival and fertility in an adverse environment

Background

The apolipoprotein-ε4 allele (APOE-ε4) is strongly associated with detrimental outcomes in affluent populations including atherosclerotic disease, Alzheimer’s disease, and reduced lifespan. Despite these detrimental outcomes, population frequencies of APOE-ε4 are high. We hypothesize that the high frequency of APOE-ε4 was maintained because of beneficial effects during evolution when infectious pathogens were more prevalent and a major cause of mortality. We examined a rural Ghanaian population with a high pathogen exposure for selective advantages of APOE-ε4, to survival and or fertility.

Methods and findings

This rural Ghanaian population (n = 4311) has high levels of mortality from widespread infectious diseases which are the main cause of death. We examined whether APOE-ε4 was associated with survival (total follow-up time was 30,262 years) and fertility after stratifying by exposure to high or low pathogen levels. Households drawing water from open wells and rivers were classified as exposed to high pathogen levels while low pathogen exposure was classified as those drawing water from borehole wells. We found a non-significant, but positive survival benefit, i.e. the hazard ratio per APOE-ε4 allele was 0.80 (95% confidence interval: 0.69 to 1.05), adjusted for sex, tribe, and socioeconomic status. Among women aged 40 years and older (n = 842), APOE-ε4 was not associated with the lifetime number of children. However, APOE-ε4 was associated with higher fertility in women exposed to high pathogen levels. Compared with women not carrying an APOE-ε4 allele, those carrying one APOE-ε4 allele had on average one more child and those carrying two APOE-ε4 alleles had 3.5 more children (p = 0.018).

Conclusions

Contrary to affluent modern-day populations, APOE-ε4 did not carry a survival disadvantage in this rural Ghanaian population. Moreover, APOE-ε4 promotes fertility in highly infectious environments. Our findings suggest that APOE-ε4 may be considered as evolutionarily adaptive. Its adverse associations in affluent modern populations with later onset diseases of aging further characterize APOE-ε4 as an example of antagonistic pleiotropy.

Drivers of Microbial Risk for Direct Potable Reuse and de Facto Reuse Treatment Schemes: The Impacts of Source Water Quality and Blending

Although reclaimed water for potable applications has many potential benefits, it poses concerns for chemical and microbial risks to consumers. We present a quantitative microbial risk assessment (QMRA) Monte Carlo framework to compare a de facto water reuse scenario (treated wastewater-impacted surface water) with four hypothetical Direct Potable Reuse (DPR) scenarios for Norovirus, Cryptosporidium, and Salmonella. Consumer microbial risks of surface source water quality (impacted by 0-100% treated wastewater effluent) were assessed. Additionally, we assessed risks for different blending ratios (0-100% surface water blended into advanced-treated DPR water) when source surface water consisted of 50% wastewater effluent. De facto reuse risks exceeded the yearly 10-4 infections risk benchmark while all modeled DPR risks were significantly lower. Contamination with 1% or more wastewater effluent in the source water, and blending 1% or more wastewater-impacted surface water into the advanced-treated DPR water drove the risk closer to the 10-4 benchmark. We demonstrate that de facto reuse by itself, or as an input into DPR, drives microbial risks more so than the advanced-treated DPR water. When applied using location-specific inputs, this framework can contribute to project design and public awareness campaigns to build legitimacy for DPR.

Measuring sporadic gastrointestinal illness associated with drinking water - an overview of methodologies

There is an increasing awareness that drinking water contributes to sporadic gastrointestinal illness (GI) in high income countries of the northern hemisphere. A literature search was conducted in order to review: (1) methods used for investigating the effects of public drinking water on GI; (2) evidence of possible dose-response relationship between sporadic GI and drinking water consumption; and (3) association between sporadic GI and factors affecting drinking water quality. Seventy-four articles were selected, key findings and information gaps were identified. In-home intervention studies have only been conducted in areas using surface water sources and intervention studies in communities supplied by ground water are therefore needed. Community-wide intervention studies may constitute a cost-effective alternative to in-home intervention studies. Proxy data that correlate with GI in the community can be used for detecting changes in the incidence of GI. Proxy data can, however, not be used for measuring the prevalence of illness. Local conditions affecting water safety may vary greatly, making direct comparisons between studies difficult unless sufficient knowledge about these conditions is acquired. Drinking water in high-income countries contributes to endemic levels of GI and there are public health benefits for further improvements of drinking water safety.

Burden of Disease Attributed to Waterborne Transmission of Selected Enteric Pathogens, Australia, 2010

AbstractUniversal access to safe drinking water is a global priority. To estimate the annual disease burden of campylobacteriosis, nontyphoidal salmonellosis, cryptosporidiosis, giardiasis, and norovirus attributable to waterborne transmission in Australia, we multiplied regional World Health Organization (WHO) estimates of the proportion of cases attributable to waterborne transmission by estimates of all-source disease burden for each study pathogen. Norovirus was attributed as causing the most waterborne disease cases (479,632; 95% uncertainty interval [UI]: 0-1,111,874) followed by giardiasis and campylobacteriosis. The estimated waterborne disability-adjusted life year (DALY) burden for campylobacteriosis (2,004; 95% UI: 0-5,831) was 7-fold greater than other study pathogens and exceeded the WHO guidelines for drinking water quality (1 × 10-6 DALY per person per year) by 90-fold. However, these estimates include disease transmitted via either drinking or recreational water exposure. More precise country-specific and drinking water-specific attribution estimates would better define the health burden from drinking water and inform changes to treatment requirements.

One-year Surveillance of Human Enteric Viruses in Raw and Treated Wastewaters, Downstream River Waters, and Drinking Waters

Human enteric viruses are a major cause of waterborne diseases, and can be transmitted by contaminated water of all kinds, including drinking and recreational water. The objectives of the present study were to assess the occurrence of enteric viruses (enterovirus, norovirus, adenovirus, hepatitis A and E virus) in raw and treated wastewaters, in rivers receiving wastewater discharges, and in drinking waters. Wastewater treatment plants' (WWTP) pathogen removal efficiencies by adenovirus quantitative real-time PCR and the presence of infectious enterovirus, by cell culture assays, in treated wastewaters and in surface waters were also evaluated. A total of 90 water samples were collected: raw and treated wastewaters (treated effluents and ultrafiltered water reused for industrial purposes), water from two rivers receiving treated discharges, and drinking water. Nested PCR assays were used for the identification of viral DNA/RNA, followed by direct amplicon sequencing. All raw sewage samples (21/21), 61.9 % of treated wastewater samples (13/21), and 25 % of ultrafiltered water samples (3/12) were contaminated with at least one viral family. Multiple virus families and genera were frequently detected. Mean positive PCRs per sample decreased significantly from raw to treated sewage and to ultrafiltered waters. Moreover, quantitative adenovirus data showed a reduction in excess of 99 % in viral genome copies following wastewater treatment. In surface waters, 78.6 % (22/28) of samples tested positive for one or more viruses by molecular methods, but enterovirus-specific infectivity assays did not reveal infectious particles in these samples. All drinking water samples tested negative for all viruses, demonstrating the effectiveness of treatment in removing viral pathogens from drinking water. Integrated strategies to manage water from all sources are crucial to ensure water quality.

Comparison of Risk Predicted by Multiple Norovirus Dose-Response Models and Implications for Quantitative Microbial Risk Assessment

The application of quantitative microbial risk assessments (QMRAs) to understand and mitigate risks associated with norovirus is increasingly common as there is a high frequency of outbreaks worldwide. A key component of QMRA is the dose-response analysis, which is the mathematical characterization of the association between dose and outcome. For Norovirus, multiple dose-response models are available that assume either a disaggregated or an aggregated intake dose. This work reviewed the dose-response models currently used in QMRA, and compared predicted risks from waterborne exposures (recreational and drinking) using all available dose-response models. The results found that the majority of published QMRAs of norovirus use the ₁ F₁ hypergeometric dose-response model with α = 0.04, β = 0.055. This dose-response model predicted relatively high risk estimates compared to other dose-response models for doses in the range of 1-1,000 genomic equivalent copies. The difference in predicted risk among dose-response models was largest for small doses, which has implications for drinking water QMRAs where the concentration of norovirus is low. Based on the review, a set of best practices was proposed to encourage the careful consideration and reporting of important assumptions in the selection and use of dose-response models in QMRA of norovirus. Finally, in the absence of one best norovirus dose-response model, multiple models should be used to provide a range of predicted outcomes for probability of infection.

Prevalence of rotavirus, adenovirus, hepatitis A virus and enterovirus in water samples collected from different region of Peshawar, Pakistan

Viral gastroenteritis and other water-borne diseases are the most neglected areas of research in Pakistan. To determine the quality of water, 4 enteric viruses were studied from different localities of Peshawar, Pakistan. The study validates the viral detection method for Rotavirus (RV), Human adenovirus (HAdV), Enterovirus (EV) and Hepatitis A virus (HAV), directly from water sources of rural areas of Peshawar, KPK, Pakistan. Overall, 95 five water samples were tested; among them, 9.47% were positive for RV, 38.94% for HAdV, 48.42% for EV and 12.63% for HAV. The presence of these viruses in water was directly correlated with meteorological data. High prevalence of EV and HAdV was detected frequently in the wet season from May - September, which can be the potential cause of spreading of gastroenteritis in the population. Environmental surveillance is an additional tool to evaluate the epidemiology of enteric viruses circulating in a given community.

Setback distances between small biological wastewater treatment systems and drinking water wells against virus contamination in alluvial aquifers

Contamination of groundwater by pathogenic viruses from small biological wastewater treatment system discharges in remote areas is a major concern. To protect drinking water wells against virus contamination, safe setback distances are required between wastewater disposal fields and water supply wells. In this study, setback distances are calculated for alluvial sand and gravel aquifers for different vadose zone and aquifer thicknesses and horizontal groundwater gradients. This study applies to individual households and small settlements (1-20 persons) in decentralized locations without access to receiving surface waters but with the legal obligation of biological wastewater treatment. The calculations are based on Monte Carlo simulations using an analytical model that couples vertical unsaturated and horizontal saturated flow with virus transport. Hydraulic conductivities and water retention curves were selected from reported distribution functions depending on the type of subsurface media. The enteric virus concentration in effluent discharge was calculated based on reported ranges of enteric virus concentration in faeces, virus infectivity, suspension factor, and virus reduction by mechanical-biological wastewater treatment. To meet the risk target of <10^-4infections/person/year, a 12 log₁₀ reduction was required, using a linear dose-response relationship for the total amount of enteric viruses, at very low exposure concentrations. The results of this study suggest that the horizontal setback distances vary widely ranging 39 to 144m in sand aquifers, 66-289m in gravel aquifers and 1-2.5km in coarse gravel aquifers. It also varies for the same aquifers, depending on the thickness of the vadose zones and the groundwater gradient. For vulnerable fast-flow alluvial aquifers like coarse gravels, the calculated setback distances were too large to achieve practically. Therefore, for this category of aquifer, a high level of treatment is recommended before the effluent is discharged to the ground surface.

Detection of pepper mild mottle virus as an indicator for drinking water quality in Hanoi, Vietnam, in large volume of water after household treatment

The aims of this study were to examine the removal of bacteria and viruses by household point-of-use (POU) treatments and to apply a previously developed large-volume virus concentration method (∼20 L). First, the removal of microbes by household POU treatment was investigated in the laboratory. Second, the prevalence of viruses in drinking water sources for households and the removal efficiency of microbes by POU treatments in two suburban communities in Hanoi, Vietnam, were investigated. Indigenous pepper mild mottle virus (PMMoV) was used as the main target together with adenovirus, Aichi virus, enterovirus, F-specific bacteriophage genogroup 1, and Escherichia coli to investigate the removal efficiency of household treatments. The results from laboratory and field survey were compared. From the laboratory study, ceramic membranes were not effective for removing viruses and bacteria from water; pathogen reduction was less than 1.5 log10. By contrast, reverse osmosis (RO) devices reduced microbes by 3 to > 5 log10. In a field study, PMMoV was found to be the most prevalent waterborne virus. Household sand filtration was ineffective for removing E. coli, total coliforms and PMMoV; the reduction was less than 1 order of magnitude. Boiling the water and then filtering it with a ceramic membrane reduced E. coli by 3 orders of magnitude, but this was not effective for removing PMMoV. RO filtration was one of the promising methods for removing E. coli, total coliforms and PMMoV to below their detection limits in most of the samples studied. The removal of E. coli, total coliforms and PMMoV was >2.3, >4 and >3 log10, respectively. The laboratory results of virus removal efficiency by POU devices agreed with the field study. Due to the prevalence and characteristics of PMMoV, it is a strong candidate for an indigenous indicator to investigate the viral removal efficiency of household POU treatments.

Incidence and characteristics of hepatitis E virus infection in children in Assiut, Upper Egypt

Objective To describe the characteristics of hepatitis E virus (HEV) infection in a cohort of children from Upper Egypt using data from a large multicentre prospective study of acute viral hepatitis (AVH). Methods Data from subjects aged 2-18 years with AVH or close contacts of those with AVH found to have asymptomatic AVH were included in the analysis. Information concerning medical history, clinical examination, liver function tests and screening for hepatotropic viruses was recorded and analysed. Results A total of 123 patients (73 boys, 50 girls) were included in the analysis. Of these, 33 (26.8%) had HEV infection, 17 (13.8%) had hepatitis A virus infection, 10 (8.1%) had hepatitis B virus infection, 14 (11.4%) had cytomegalovirus hepatitis, five (4.1%) had autoimmune hepatitis, 11 (8.9%) had hepatitis due to mixed viral infections and 33 (26.8%) had non A-E hepatitis. Overall, 38 (30.9%) had infection with HEV. HEV infection was significantly higher among those using underground wells as a water source compared with tap water. Liver enzymes were significantly raised in patients with non-HEV infection compared with those with HEV infection. Conclusions HEV is a significant cause of AVH among children in Upper Egypt. Contamination of drinking water appears to be a major source of infection. Screening for HEV should be considered in all Egyptian children with AVH.

Evaluation of virus removal efficiency of coagulation-sedimentation and rapid sand filtration processes in a drinking water treatment plant in Bangkok, Thailand

In order to properly assess and manage the risk of infection by enteric viruses in tap water, virus removal efficiency should be evaluated quantitatively for individual processes in actual drinking water treatment plants (DWTPs); however, there have been only a few studies due to technical difficulties in quantifying low virus concentration in water samples. In this study, the removal efficiency of indigenous viruses was evaluated for coagulation-sedimentation (CS) and rapid sand filtration (RSF) processes in a DWTP in Bangkok, Thailand by measuring the concentration of viruses before and after treatment processes using real-time polymerase chain reaction (qPCR). Water samples were collected and concentrated from raw source water, after CS, and after RSF, and inhibitory substances in water samples were reduced by use of a hydrophobic resin (DAX-8). Pepper mild mottle virus (PMMoV) and JC polyomavirus (JC PyV) were found to be highly prevalent in raw waters, with concentrations of 10(2.88 ± 0.35) and 10(3.06 ± 0.42) copies/L (geometric mean ± S.D.), respectively. Step-wise removal efficiencies were calculated for individual processes, with some variation observed between wet and dry seasons. During the wet season, PMMoV was removed less by CS and more by RSF on average (0.40 log10 vs 1.26 log10, respectively), while the reverse was true for JC PyV (1.91 log10 vs 0.49 log10, respectively). Both viruses were removed similarly during the dry season, with CS removing the most virus (PMMoV, 1.61 log10 and 0.78 log10; JC PyV, 1.70 log10, and 0.59 log10; CS and RSF, respectively). These differences between seasons were potentially due to variations in raw water quality and the characteristics of the viruses themselves. These results suggest that PMMoV and JC PyV, which are more prevalent in environmental waters than the other enteric viruses evaluated in this study, could be useful in determining viral fate for the risk management of viruses in water treatment processes in actual full-scale DWTPs.