Concentration Of Enteric Viruses Research Articles

Waterborne Virus Transport and Risk Assessment in Lake Geneva Under Climate Change

AbstractClimate changes influence lake hydrodynamics and radiation levels and thus may affect the fate and transport of waterborne pathogens in lakes. This study examines the impact of climate change on the fate, transport, and associated risks of four waterborne viruses in Lake Geneva. We used a coupled water quality‐microbial risk assessment model to estimate virus concentrations and associated risks to recreational water users for each month in 2019 and 2060. Long‐term hydrodynamic simulations suggested that although the annual hydrodynamic transport pattern of Lake Geneva will remain relatively stable, a 1.9°C increase of lake surface water temperature can be expected, while a slight decrease in lake current velocity may occur. The subsequent effect on the fate and transport of the four enteric viruses was found to vary by time of year. During warmer periods, the increase of virus inactivation due to higher water temperature and stronger solar radiation at the earth's surface will compensate for the additional virus discharge brought about by population growth over the time period considered, whereas during winter the virus concentration near the lake shore and the associated infection probabilities risks are likely to increase due to population growth. Additionally, the current estimation of virus inactivation rate shows significant variability, which has a more substantial effect on enteric virus concentrations in the lake compared with changing climate parameters. Overall, the study suggests that future risks posed by enteric viruses with recreational water users near popular beaches around Lake Geneva will likely remain similar to current risks and accurate estimation of the environmental inactivation of viruses is crucial for predicting the fate of enteric viruses in the aquatic system.

Predicting the concentrations of enteric viruses in urban rivers running through the city center via an artificial neural network

Viral waterborne diseases are widespread in cities due largely to the occurrence of enteric viruses in urban rivers, which pose a significant concern to human health. Yet, the application of rapid detection technology for enteric viruses in environmental water remains undeveloped globally. Here, multiple linear regression (MLR) modeling and artificial neural network (ANN) modeling, which used frequently measured physicochemical parameters in river water, were constructed to predict the concentration of enteric viruses including human enteroviruses (EnVs), rotaviruses (HRVs), astroviruses (AstVs), noroviruses GⅡ (HuNoVs GⅡ), and adenoviruses (HAdVs) in rivers. After training, testing, and validating, ANN models showed better performance than any MLR model for predicting the viral concentration in Jinhe River. All determined R-values for ANN models exceeded 0.89, suggesting a strong correlation between the predicted and measured outputs for target enteric viruses. Furthermore, ANN models provided a better congruence between the observed and predicted concentrations of each virus than MLR models did. Together, these findings strongly suggest that ANN modeling can provide more accurate and timely predictions of viral concentrations based on frequent (or routine) measurements of physicochemical parameters in river water, which would improve assessments of waterborne disease prevalence in cities.

Environmental Survey of Rotavirus in Sewage Water within Maiduguri Metropolis, Nigeria

Background and study aim: Inadequately treated water supply and unhygienic food consumption are the major sources of contracting feco-orally transmitted viral pathogens, including Rotavirus. This prospective study aimed to assess the presence of Rotavirus in sewage, underground and surface waters collected from different locations within Maiduguri Metropolis, Nigeria. Materials and Methods: A total of 170 sewage and water samples (underground and surface waters) were collected from various sources in high-density and low-density areas of the Maiduguri metropolis. A modified adsorption- elution method for concentration of enteric viruses in sewage and water samples and detection of the presence of rotavirus (if present) was done using Enzyme linked immune-sorbent assay (ELISA). The viruses in water were concentrated by negatively charged membrane filtration, eluted with 0.05M Glycine at pH 11.5, and re-concentrated by centrifugation at 12,000rpm for one hour. Results: Out of the 60 domestic sewage samples collected from high-density areas, 8.3% were positive for rotavirus antigen, whereas none of the samples from low-density areas were positive. In addition, rotavirus antigen was not detected in underground and surface water samples. The temperature range of the 5 rotavirus positive samples was 23-30oC. All the 5 positive samples had alkaline pH that ranged between 8 and 9. Conclusion: This study has demonstrated the persistence of rotavirus in sewage and its possible transmission through contaminated food and poor treated water

Surveillance of Enteric Viruses and Thermotolerant Coliforms in Surface Water and Bivalves from a Mangrove Estuary in Southeastern Brazil.

This study was conducted to evaluate the microbiological quality of a mangrove estuary in the Vitória Bay region, Espírito Santo, Brazil. We analyzed the presence and concentration of enteric viruses and thermotolerant coliforms in water, mussels (Mytella charruana and Mytella guyanensis), and oysters (Crassostrea rhizophorae), collected over a 13-month period. Human adenovirus, rotavirus A (RVA), and norovirus genogroup II were analyzed by quantitative PCR. The highest viral load was found in RVA-positive samples with a concentration of 3.0 × 104genome copies (GC)L-1 in water samples and 1.3 × 105GCg-1 in bivalves. RVA was the most prevalent virus in all matrices. Thermotolerant coliforms were quantified as colony-forming units (CFU) by the membrane filtration method. The concentration of these bacteria in water was in accordance with the Brazilian standard for recreational waters (< 250CFU 100mL-1) during most of the monitoring period (12 out of 13months). However, thermotolerant coliform concentrations of 3.0, 3.1, and 2.6 log CFU 100g-1 were detected in M. charruana, M. guyanensis, and C. rhizophorae, respectively. The presence of human-specific viruses in water and bivalves reflects the strong anthropogenic impact on the mangrove and serves as an early warning of waterborne and foodborne disease outbreaks resulting from the consumption of shellfish and the practice of water recreational activities in the region.

Human health risk assessment for the occurrence of enteric viruses in drinking water from wells: Role of flood runoff injections

We demonstrated that floods can induce severe microbiological contamination of drinking water from wells and suggest strategies to better address water safety plans for groundwater drinking supplies. Since 2002, the Italian Water Research Institute (IRSA) has detected hepatitis A virus, adenovirus, rotavirus, norovirus, and enterovirus in water samples from wells in the Salento peninsula, southern Italy. Perturbations in the ionic strength in water flow can initiate strong virus detachments from terra rossa sediments in karst fractures. This study therefore explored the potential health impacts of prolonged runoff injections in Salento groundwater caused by severe flooding during October 2018. A mathematical model for virus fate and transport in fractures was applied to determine the impact of floodwater injection on groundwater quality by incorporating mechanisms that affect virus attachment/detachment and survival in flowing water at microscale. This model predicted target concentrations of enteric viruses that can occur unexpectedly in wells at considerable distances (5–8 km) from the runoff injection site (sinkhole). Subsequently, the health impact of viruses in drinking water supplied from contaminated wells was estimated during the summer on the Salento coast. Specific unpublished dose-response model coefficients were proposed to determine the infection probabilities for Echo-11 and Polio 1 enteroviruses through ingestion. The median (50%) risk of infection was estimated at 6.3 · 10−3 with an uncertainty of 23%. The predicted burden of diseases was 4.89 disability adjusted life years per year, i.e., twice the maximum tolerable disease burden. The results highlight the requirement for additional water disinfection treatments in Salento prior to the distribution of drinking water. Moreover, monthly controls of enteric virus occurrence in water from wells should be imposed by a new water framework directive in semiarid regions because of the vulnerability of karst carbonate aquifers to prolonged floodwater injections and enteric virus contamination.

Two-Step Concentration of Complex Water Samples for the Detection of Viruses.

The accurate detection and quantification of pathogenic viruses in water is essential to understand and reduce the risk of human infection. This paper describes a two-step method suitable for concentrating viruses in water and wastewater samples. The method involves a tangential flow ultrafiltration step that reduces the sample volume of 1–10 L to approximately 50 mL, followed by secondary precipitation using polyethylene glycol 6000, which reduces the volume to 1–4 mL. For method validation, water samples were spiked with different concentrations of enteric viruses, and viral recovery in the concentrates exceeded 10% in all experiments. The method is suitable for water samples with high and low salinity and turbidity, allowing an accurate comparison of viral titers in a diverse range of water types. Furthermore, the method has the potential to concentrate other pathogens, e.g., bacteria or protozoa. Hence, the use of this method can improve the holistic assessment of risks associated with wastewater-contaminated environments.

Irrigating Lettuce with Wastewater Effluent: Does Disinfection with Chlorine Dioxide Inactivate Viruses?

Reclaimed water obtained from urban wastewater is currently being used as irrigation water in water-scarce regions in Spain. However, wastewater can contain enteric viruses that water reclamation treatment cannot remove or inactivate completely. In the present study, greenhouse-grown baby lettuce ( L.) was irrigated with secondary treatment effluent from a wastewater treatment plant untreated and treated using chlorine dioxide (ClO). The effect of ClO treatment on the physicochemical characteristics and the presence of enteric viruses in irrigation water and lettuce was assessed. The presence of human noroviruses genogroups I and II (NoV GI and NoV GII), and human astroviruses (HAstV), was analyzed by real-time polymerase chain reaction (RT-qPCR). Additionally, to check for the loss of infectivity induced by the disinfection treatment, positive samples were re-analyzed after pretreatment with the intercalating dye PMAxx before RNA extraction and RT-qPCR. There were no significant differences in the proportion of positive samples and the concentration of enteric viruses between treated and untreated reclaimed water without PMAxx pretreatment ( > 0.05). A significantly lower concentration of NoV GI was detected in ClO-treated water when samples were pretreated with PMAxx ( < 0.05), indicating that inactivation was due to the disinfection treatment. Laboratory-scale validation tests indicated the suitability of PMAxx-RT-qPCR for discrimination between potentially infectious and ClO-damaged viruses. Although the applied ClO treatment was not able to significantly reduce the enteric virus load of the secondary effluent from the wastewater treatment plant, none of the lettuce samples analyzed ( = 36) was positive for the presence of NoV or HAstV.

Presence of Human Enteric Viruses, Protozoa, and Indicators of Pathogens in the Bagmati River, Nepal.

Quantification of waterborne pathogens in water sources is essential for alerting the community about health hazards. This study determined the presence of human enteric viruses and protozoa in the Bagmati River, Nepal, and detected fecal indicator bacteria (total coliforms, Escherichia coli, and Enterococcus spp.), human-fecal markers (human Bacteroidales and JC and BK polyomaviruses), and index viruses (tobacco mosaic virus and pepper mild mottle virus). During a one-year period between October 2015 and September 2016, a total of 18 surface water samples were collected periodically from three sites along the river. Using quantitative polymerase chain reaction, all eight types of human enteric viruses tested—including adenoviruses, noroviruses, and enteroviruses, were detected frequently at the midstream and downstream sites, with concentrations of 4.4–8.3 log copies/L. Enteroviruses and saliviruses were the most frequently detected enteric viruses, which were present in 72% (13/18) of the tested samples. Giardia spp. were detected by fluorescence microscopy in 78% (14/18) of the samples, with a lower detection ratio at the upstream site. Cryptosporidium spp. were detected only at the midstream and downstream sites, with a positive ratio of 39% (7/18). The high concentrations of enteric viruses suggest that the midstream and downstream regions are heavily contaminated with human feces and that there are alarming possibilities of waterborne diseases. The concentrations of enteric viruses were significantly higher in the dry season than the wet season (p < 0.05). There was a significant positive correlation between the concentrations of human enteric viruses and the tested indicators for the presence of pathogens (IPP) (p < 0.05), suggesting that these IPP can be used to estimate the presence of enteric viruses in the Bagmati River water.

A 1-Year Study on the Detection of Human Enteric Viruses in New Caledonia.

Human enteric viruses occur in high concentrations in wastewater and can contaminate receiving environmental waters. Due to the lack of data on the prevalence of enteric viruses in New Caledonia, the presence and the concentrations of enteric viruses in wastewater and seawater were determined. Untreated wastewater and seawater samples were collected monthly for 1 year from a wastewater treatment plant (WWTP) and from the WWTP's outlet, located directly on a popular recreational beach. Samples were tested for norovirus genogroups I and II (NoV GI and GII), astroviruses (AsV), sapoviruses (SaV), enteroviruses (EV), hepatitis A viruses (HAV), rotaviruses (RoV), human adenoviruses (HAdV) and human polyomaviruses (HPyV). To support these data, faecal samples from cases of gastroenteritis were tested for the first time for NoV and detected in the population. NoV GI, NoV GII, EV, SaV, HAdV and HPyV were detected in all wastewaters, RoV in 75% and AsV in 67%. HAV were not detected in wastewater. Overall, 92% of seawater samples were positive for at least one virus. HPyV were detected most frequently in 92% of samples and at concentrations up to 7.7 × 10(3) genome copies/L. NoV GI, NoV GII, EV, SaV, RoV and HAdV were found in 33, 66, 41, 33, 16 and 66% of seawater samples, respectively. AsV were not detected in seawater. This study reports for the first time the presence of NoV and other enteric viruses in New Caledonia and highlights the year-round presence of enteric viruses in the seawater of a popular beach.

Rapid, simple and efficient method for detection of viral genomes on raspberries

In recent years, foodborne viruses, especially human noroviruses (NoV) and hepatitis A virus (HAV), have been increasingly reported as the causes of foodborne disease outbreaks. Soft red fruits, especially raspberries, have a high incidence among the types of food concerned. Due to low infectious doses and low concentrations of enteric viruses in food samples, it is necessary to have an efficient and rapid detection method to implement prevention measures. A standard method for virus detection and quantification in food, including raspberries (XP CEN ISO/TS 15216-1 and -2, 2013) is currently available. This method proposes a consensus detection approach by RT-real time PCR (RT-qPCR) but also a virus extraction procedure based on the elution-concentration principle. In this study, an alternative method of extraction in which RNAs are directly extracted from food matrices (based on direct RNA extraction) has been optimized. First, each step was improved to make it a highly rapid, specific and simple method. Second, the standard virus concentration method was compared with the optimized direct RNA extraction one. Human enteric viral surrogates, Murine Norovirus (MNV) and F-specific RNA bacteriophage GA, were selected according to their adhesion properties and resistance to pH close to our main targets (NoV and HAV). Raspberries were artificially contaminated using two different techniques (immersion and spotting) in order to define a recovery rate and the amounts of virus recovered. Results showed that the direct RNA extraction method revealed significantly higher viral extraction efficiency (46.2%) than the elution-concentration method (20.3%), with similar proportions of inhibitors for both. In the same way with inoculation by spotting, the best recovery rate of GA phage (39.7% against 0.7%) and MNV (42.8% against 0.5%) was observed by direct RNA extraction. For the lowest concentrations of phage and virus in the immersion bath, only the direct RNA extraction method allowed their recovery. Direct RNA extraction proved to be more effective (best recovery rate), faster (<8h) and simpler (fewer steps) than the one proposed in the CEN ISO standard method when it came to detecting enteric viruses on raspberries.

Concentration of enteric viruses from tap water using an anion exchange resin-based method

Detecting low concentrations of enteric viruses in water is needed for public health-related monitoring and control purposes. Thus, there is a need for sensitive, rapid and cost effective enteric viral concentration methods compatible with downstream molecular detection. Here, a virus concentration method based on adsorption of the virus to an anion exchange resin and direct isolation of nucleic acids is presented. Ten liter samples of tap water spiked with different concentrations (10–10,000TCID50/10L) of human adenovirus 40 (HAdV-40), hepatitis A virus (HAV) or rotavirus (RV) were concentrated and detected by real time PCR or real time RT-PCR. This method improved viral detection compared to direct testing of spiked water samples where the ΔCt was 12.1 for AdV-40 and 4.3 for HAV. Direct detection of RV in water was only possible for one of the three replicates tested (Ct of 37), but RV detection was improved using the resin method (all replicates tested positive with an average Ct of 30, n=3). The limit of detection of the method was 10TCID50/10L for HAdV-40 and HAV, and 100TCID50/10L of water for RV. These results compare favorably with detection limits reported for more expensive and laborious methods.

Surveillance of enteric viruses and coliphages in a tropical urban catchment

An assessment of the occurrence and concentration of enteric viruses and coliphages was carried out in highly urbanized catchment waters in the tropical city-state of Singapore. Target enteric viruses in this study were noroviruses, adenoviruses, astroviruses and rotaviruses. In total, 65 water samples were collected from canals and the reservoir of the Marina catchment on a monthly basis over a period of a year. Quantitative PCR (qPCR) and single agar layer plaque assay (SAL) were used to enumerate target enteric viruses and coliphages in water samples, respectively. The most prevalent pathogen were noroviruses, detected in 37 samples (57%), particularly norovirus genogroup II (48%), with a mean concentration of 3.7 × 102 gene copies per liter. Rotavirus was the second most prevalent virus (40%) with a mean concentration of 2.5 × 102 GC/L. The mean concentrations of somatic and male-specific coliphages were 2.2 × 102 and 1.1 × 102 PFU/100 ml, respectively. The occurrence and concentration of each target virus and the ratio of somatic to male-specific coliphages varied at different sampling sites in the catchment. For sampling sites with higher frequency of occurrence and concentration of viruses, the ratio of somatic to male-specific coliphages was generally much lower than other sampling sites with lower incidences of enteric viruses. Overall, higher statistical correlation was observed between target enteric viruses than between enteric viruses and coliphages. However, male-specific coliphages were positively correlated with norovirus concentrations. A multi-level integrated surveillance system, which comprises the monitoring of bacterial indicators, coliphages and selected enteric viruses, could help to meet recreational and surface water quality criteria in a complex urbanized catchment.

Advice to Risk Assessors Modeling Viral Health Risk Associated with Household Graywater

Quantitative microbial risk assessment (QMRA) is a valuable tool that can be used to predict the risk associated with human exposure to specific microbial contaminants in water sources. The transparency inherent in the QMRA process benefits discussions between multidisciplinary teams because members of such teams have different expertise and their confidence in the risk assessment output will depend upon whether they regard the selected input data and assumptions as being suitable and/or plausible. Selection of input data requires knowledge of the availability of appropriate data sets, the limitations of using a particular data set, and the logic of using alternative approaches. In performing QMRA modeling and in the absence of directly relevant data, compromises must be made. One such compromise made is to use available Escherichia coli data and apply a ratio of enteric viruses to indicator E. coli in wastewater obtained from prior studies to estimate the concentration of enteric viruses in other wastewater types/sources. In this article, we have provided an argument for why we do not recommend the use of a pathogen to E. coli ratio to estimate virus concentrations in single household graywater and additionally suggested circumstances in which use of such a ratio may be justified.

Comparison of two extraction methods for the detection of hepatitis A virus in lettuces using the murine norovirus as a process control

Enteric viruses are important agents of foodborne diseases. In recent years, raw fruits and vegetables have frequently been involved in foodborne transmission of enteric viruses to humans, particularly noroviruses and hepatitis A virus (HAV). Although viral contamination can occur at any stage of food processing, primary production is a critical stage in which prevention measures are essential to minimise the risk of infection to consumers. Due to the low infectious doses and low concentrations of enteric viruses in food samples, an efficient and rapid virus concentration method is required for routine control and risk assessment. In this study, the virus concentration reference method proposed by the CEN/TC275/WG6/TAG4 working group for samples of soft fruits and salad vegetables was compared with a method including a filtration step in order to recover hepatitis A virus (HAV) on lettuces. Murine norovirus (MNV-1) was used as a process control and detected simultaneously with HAV in a one-step duplex RT-qPCR following both procedures. The HAV LOD ranged from 10 to 100 PFU/25g of lettuce in the presence or absence of MNV-1, regardless of method used. In conclusion, MNV-1 offers a very reliable and simple way to monitor the quality of the detection procedures. Although it has been found that both methods achieved an identical limit of detection, the method including a filtration step requires less processing and could be proposed as an alternative method.

A 5‐year survey (2007–2011) of enteric viruses in Korean aquatic environments and the use of coliforms as viral indicators

Three hundred and thirty-nine water samples obtained from 90 locations in Korea from 2007 to 2011 were tested for the presence of enteric viruses (EV), total coliforms (TC), and fecal coliforms (FC). A total culturable virus assay revealed that 89 samples (26.3%) were positive for EVs, the average concentration being 5.8 most probable number (MPN)/100 L. The Han river basin exhibited the highest contamination by EVs (occurrence, 41.3%; average concentration, 24.0 MPN/100 L). EV contamination was found more frequently in river water (occurrence, 33.6%; concentration, 8.4 MPN/100 L) than in lake water or groundwater. The concentration of EVs was highest in spring (7.7 MPN/100 L), whereas it was found most frequently in winter (36.1%). The number of TCs ranged from 0 - 1.2 × 10(5) colony forming units (CFU)/100 mL and that of FCs from 0-6.2 × 10(3) CFU/100 mL per sample. Statistical analyses showed that the presence of EVs, TCs and FCs did not correlate significantly with temperature or turbidity. In addition, presence of TCs and FCs was not significantly correlated with presence of EVs. In conclusion, TCs and FCs may not be accurate microbial indicators of waterborne EVs in Korean aquatic environments.

A single method for recovery and concentration of enteric viruses and bacteria from fresh-cut vegetables

Fresh-cut vegetables are prone to be contaminated with foodborne pathogens during growth, harvest, transport and further processing and handling. As most of these products are generally eaten raw or mildly treated, there is an increase in the number of outbreaks caused by viruses and bacteria associated with fresh vegetables. Foodborne pathogens are usually present at very low levels and have to be concentrated (i.e. viruses) or enriched (i.e. bacteria) to enhance their detection. With this aim, a rapid concentration method has been developed for the simultaneous recovery of hepatitis A virus (HAV), norovirus (NV), murine norovirus (MNV) as a surrogate for NV, Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enterica. Initial experiments focused on evaluating the elution conditions suitable for virus release from vegetables. Finally, elution with buffered peptone water (BPW), using a Pulsifier, and concentration by polyethylene glycol (PEG) precipitation were the methods selected for the elution and concentration of both, enteric viruses and bacteria, from three different types of fresh-cut vegetables by quantitative PCR (qPCR) using specific primers. The average recoveries from inoculated parsley, spinach and salad, were ca. 9.2%, 43.5%, and 20.7% for NV, MNV, and HAV, respectively. Detection limits were 132 RT-PCR units (PCRU), 1.5 50% tissue culture infectious dose (TCID₅₀), and 6.6 TCID₅₀ for NV, MNV, and HAV, respectively. This protocol resulted in average recoveries of 57.4%, 64.5% and 64.6% in three vegetables for E. coli O157:H7, L. monocytogenes and Salmonella with corresponding detection limits of 10³, 10² and 10³ CFU/g, respectively. Based on these results, it can be concluded that the procedure herein is suitable to recover, detect and quantify enteric viruses and foodborne pathogenic bacteria within 5 h and can be applied for the simultaneous detection of both types of foodborne pathogens in fresh-cut vegetables.

Occurrence of adenovirus and other enteric viruses in limited-contact freshwater recreational areas and bathing waters

The goal of this study was to characterize enteric virus concentrations and their infectivity in a variety of limited-contact recreation and bathing waters, including Great Lakes beaches, inland lakes, rivers, and an effluent-dominated urban waterway. Additionally, we evaluated associations between point sources of human faecal pollution and enterovirus and adenovirus presence and concentrations. Quantitative polymerase chain reaction (qPCR) and two cell culture lines were used to identify and quantify viruses in water samples. The presence of human adenoviruses F was strongly associated with effluent-dominated waters (odds ratio 6·1, confidence interval 2·3, 15·7), as was adenovirus concentration; though, neither enterovirus presence nor concentration was associated with an effluent source. Samples with high concentrations of qPCR targets all tested positive by cell culture on both cell lines, although qPCR target concentrations were not correlated with culture values. Adenovirus was strongly associated with point sources of human faecal pollution while enterovirus was not, indicating that adenovirus measured by qPCR is a better target than enterovirus for identifying wastewater discharges in recreational freshwaters. The development of monitoring for enteric human viral pathogens at recreational waters should include adenovirus testing. Further research is needed to interpret the results of qPCR testing in relationship to the presence of infectious viruses using cell culture.

Application of Pesticide Sprays to Fresh Produce: A Risk Assessment for Hepatitis A and Salmonella

The purpose of this study was to quantify the transfer of viral and bacterial pathogens in water used to dilute pesticides sprayed onto the surfaces of cantaloupe, iceberg lettuce, and bell peppers. The average percent transfer of bacteria was estimated to range from 0.00021 to 9.4%, while average viral transfer ranged from 0.055 to 4.2%, depending on the type of produce. Based on these values the concentrations of hepatitis A virus (HAV) and Salmonella in water necessary to achieve a 1:10,000 annual risk of infection were calculated. Under worst case scenario assumptions, in which a pesticide is applied on the same day that the produce is harvested and when maximum transfer values are used, concentrations of 1.5 × 10−3 CFU Salmonella or 2.7 × 10−7 MPN HAV per 100 ml of the water used for application would result in 1:10,000 annual infection risk to anyone who consumes the fresh produce. If harvesting does not occur until at least 14 days after the application, to produce the same risk of infection, the numbers of Salmonella in 100 ml of water used to dilute the pesticides will be greater by up to five orders of magnitude, while the HAV numbers will have increased by up to two orders of magnitude. Based on the reported concentrations of enteric viruses in surface and ground waters in the United States, a 1:10,000 annual risk of infection could easily be exceeded with some groundwater sources used in the United States. To reduce the risks associated with the consumption of fresh produce, water used to prepare pesticides in spray applications should be evaluated for its microbiological quality.

Pathogens and Indicators in United States Class B Biosolids: National and Historic Distributions

This paper reports on a major study of the incidence of indicator organisms and pathogens found within Class B biosolids within 21 samplings from 18 wastewater treatment plants across the United States. This is the first major study of its kind since the promulgation of the USEPA Part 503 Rule in 1993, and includes samples before and after the Part 503 Rule was promulgated. National distributions collected between 2005 and 2008 show that the incidence of bacterial and viral pathogens in Class B mesophilic, anaerobically digested biosolids were generally low with the exception of adenoviruses, which were more prevalent than enteric viruses. No Ascaris ova were detected in any sample. In contrast, indicator organism numbers were uniformly high, regardless of whether they were bacteria (fecal coliforms) or viruses (phage). Indicators were not correlated with pathogen loads. Historic distributions were collected between 1988 and 2006 at one location in Tucson, AZ. By comparing data collected before and after 1993, the influence of the USEPA Part 503 Rule on indicator and pathogen levels within Class B biosolids can be inferred. In general, the bacterial indicators total and fecal coliforms decreased from the 1980s to present. Enteric virus concentrations after 1993 are much lower than those reported in other studies in the 1980s, although our values from 1988 to 1993 are not significantly different from our values obtained from 1994 to 2006. Presumably this is due to better and more consistent treatment of the wastewater, illustrating that the Part 503 Rule has been effective in reducing public exposure to pathogens relative to 17 yr ago. The percent reduction of both indicators and pathogens during anaerobic mesophilic digestion was between 94 and 99% for all organisms, illustrating that such treatment is effective in reducing pathogen loads.

Simultaneous Concentration of Enteric Viruses and Protozoan Parasites: A Protocol Based on Tangential Flow Filtration and Adapted to Large Volumes of Surface and Drinking Waters

A filtration system, based on tangential flow filtration (TFF) followed by ultracentrifugation was developed in order to concentrate simultaneously viruses and parasites from large volumes of water. For TFF, no pre-treatment of the membrane is performed but a post-rinsing step using high pH-beef extract-based eluant. Applying our protocol to 20 l of surface waters spiked with vaccinal poliovirus-1, ϕX174 and MS2 bacteriophages resulted in an averaged viral recovery of 75% by TFF and 91% by ultracentrifugation (total viral recovery of 70%). Our protocol was further applied to 31 environmental samples including surface, ground and drinking waters from the Grand Duchy of Luxembourg in order to assess the occurrence of protozoan parasites (Cryptosporidium parvum and Giardia lamblia (oo)cysts), pathogenic viruses (enterovirus, norovirus and adenovirus) and infectious bacteriophages (somatic coliphages and F-specific phages) in these samples. High viral recovery rates of > 70% were confirmed concentrating environmental strains of somatic and F-specific coliphages from non-spiked surface waters. Parasites and enteric viruses were detected in 86 and 40% of the surface waters used for drinking water production, respectively. Infectious bacteriophages were isolated from all surface waters and in two out of seven (29%) groundwaters revealing a susceptibility of the corresponding wells to viral pollution. TFF-based method proved to be efficient for surveying the occurrence of non-bacterial pathogens such as enteric viruses and protozoan parasites in large volumes of environmental waters.