New tools for the study and direct surveillance of viral pathogens in water

Estimation of contamination sources of human enteroviruses in a wastewater treatment and reclamation system by PCR-DGGE

A polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) method was employed to estimate the contamination sources of human enteroviruses and understand how their dominant strains vary in a wastewater treatment and reclamation system consisting of sewage collection, wastewater treatment with membrane bioreactor and open lakes for reclaimed water storage and reuse. After PCR-DGGE using a selected primer set targeting enteroviruses, phylogenetic analysis of acquired enterovirus gene sequences was performed. Enteroviruses identified from the septic tank were much more diverse than those from grey water and kitchen wastewater. Several unique types of enterovirus different from those in wastewater samples were dominant in a biological wastewater treatment unit. Membrane filtration followed by chlorination was proved effective for physically eliminating enteroviruses; however, secondary contamination likely occurred as the reclaimed water was stored in artificial lakes. Enterovirus 71 (EV71), a hand-foot-and-mouth disease (HFMD) viral pathogen, was detected mainly from the artificial lakes, implying that wastewater effluent was not the contamination source of EV71 and that there were unidentified non-point sources of the contamination with the HFMD viral pathogen in the reclaimed water stored in the artificial lakes. The PCR-DGGE targeting enteroviruses provided robust evidence about viral contamination sources in the wastewater treatment and reclamation system.

Assessment of the risks for human health of adenoviruses, hepatitis A virus, rotaviruses and enteroviruses in the Buffalo River and three source water dams in the Eastern Cape

Buffalo River is an important water resource in the Eastern Cape Province of South Africa. The potential risks of infection constituted by exposure to human enteric viruses in the Buffalo River and three source water dams along its course were assessed using mean values and static quantitative microbial risk assessment (QMRA). The daily risks of infection determined by the exponential model [for human adenovirus (HAdV) and enterovirus (EnV)] and the beta-Poisson model (for hepatitis A virus (HAV) and rotavirus (RoV)) varied with sites and exposure scenario. The estimated daily risks of infection values at the sites where the respective viruses were detected, ranged from 7.31 × 10(-3) to 1 (for HAdV), 4.23 × 10(-2) to 6.54 × 10(-1) (RoV), 2.32 × 10(-4) to 1.73 × 10(-1) (HAV) and 1.32 × 10(-4) to 5.70 × 10(-2) (EnV). The yearly risks of infection in individuals exposed to the river/dam water via drinking, recreational, domestic or irrigational activities were unacceptably high, exceeding the acceptable risk of 0.01% (10(-4) infection/person/year), and the guideline value used as by several nations for drinking water. The risks of illness and death from infection ranged from 6.58 × 10(-5) to 5.0 × 10(-1) and 6.58 × 10(-9) to 5.0 × 10(-5), respectively. The threats here are heightened by the high mortality rates for HAV, and its endemicity in South Africa. Therefore, we conclude that the Buffalo River and its source water dams are a public health hazard. The QMRA presented here is the first of its kinds in the Eastern Cape Province and provides the building block for a quantitatively oriented local guideline for water quality management in the Province.

Assessment of water quality in a border region between the Atlantic forest and an urbanised area in Rio de Janeiro, Brazil

The preservation of water resources is one of the goals of the designation of parks that act as natural reservoirs. In order to assess the impact of the presence of humans in an environmental preservation area bordering urban areas, the presence of four pathogenic enteric viruses [group A rotavirus (RV-A), norovirus (NoV), human adenoviruses (HAdV), and hepatitis A virus (HAV)], as well as the physico-chemical parameters, and Escherichia coli levels were assessed in riverine water samples. From June 2008 to May 2009, monthly monitoring was performed along the Engenho Novo River. RV-A, NoV, and HAdV were observed in 29% (31/108) of the water samples, with concentrations of up to 10(3) genome copies/liter. The natural occurrence of infectious HAdV was demonstrated by Integrated Cell Culture-PCR (ICC-PCR). This study confirms the suitability of using the detection of fecal-oral transmitted viruses as a marker of human fecal contamination in water matrices and indicates the spread of pathogenic viruses occurring in an alleged area of environmental protection.

Water quality indicators: bacteria, coliphages, enteric viruses

Water quality through the presence of pathogenic enteric microorganisms may affect human health. Coliform bacteria, Escherichia coli and coliphages are normally used as indicators of water quality. However, the presence of above-mentioned indicators do not always suggest the presence of human enteric viruses. It is important to study human enteric viruses in water. Human enteric viruses can tolerate fluctuating environmental conditions and survive in the environment for long periods of time becoming causal agents of diarrhoeal diseases. Therefore, the potential of human pathogenic viruses as significant indicators of water quality is emerging. Human Adenoviruses and other viruses have been proposed as suitable indices for the effective identification of such organisms of human origin contaminating water systems. This article reports on the recent developments in the management of water quality specifically focusing on human enteric viruses as indicators.

Waterborne human pathogenic viruses of public health concern

In recent years, the impending impact of waterborne pathogens on human health has become a growing concern. Drinking water and recreational exposure to polluted water have shown to be linked to viral infections, since viruses are shed in extremely high numbers in the faeces and vomit of infected individuals and are routinely introduced into the water environment. All of the identified pathogenic viruses that pose a significant public health threat in the water environment are transmitted via the faecal-oral route. This group, are collectively known as enteric viruses, and their possible health effects include gastroenteritis, paralysis, meningitis, hepatitis, respiratory illness and diarrhoea. This review addresses both past and recent investigations into viral contamination of surface waters, with emphasis on six types of potential waterborne human pathogenic viruses. In addition, the viral associated illnesses are outlined with reference to their pathogenesis and routes of transmission.

One-step RT-droplet digital PCR: a breakthrough in the quantification of waterborne RNA viruses

Water contamination by viruses has an increasing worldwide impact on human health, and has led to requirements for accurate and quantitative molecular tools. Here, we report the first one-step reverse-transcription droplet digital PCR-based absolute quantification of a RNA virus (rotavirus) in different types of surface water samples. This quantification method proved to be more precise and more tolerant to inhibitory substances than the benchmarking reverse-transcription real-time PCR (RT-qPCR), and needs no standard curve. This new tool is fully amenable for the quantification of viruses in the particularly low concentrations usually found in water samples.

Genetic analysis of poliovirus strains isolated from sewage in Poland

The study describes genetic characterization of poliovirus (PV) strains isolated from sewage samples in Poland. The analyses were performed for the detection of any putative polio revertants and recombinants in three genomic regions by sequencing analysis. Thirty-six strains were analyzed. The analyzed strains were identified by neutralization assay as 7 strains of serotype P1, 10 strains of serotype P2, and 19 strains of serotype P3. Sewage isolates were sequenced in 5'UTR, VP1, and 3D genomic regions. All detected PVs were classified as vaccine strains on the basis of VP1 sequence. Mutational differences in the VP1 sequences of isolated viruses ranged from 0.0% to 0.4%, indicating a limited replication period. The genetic analysis of the 3D region showed that some strains have recombinant genomes. Nine strains were found as dipartite recombinants (seven strains--S3/S2, one strain--S2/S1, one strain--S3/S1), while one strain was found as tripartite recombinant (S3/S2/S1). No recombinants with non-PV enteroviruses were identified. None of wild-type PVs or vaccine-derived polioviruses (VDPVs) were detected. This study showed the absence of wild or VDPV circulation in the country and demonstrated the usefulness of environmental surveillance in addition to acute flaccid paralysis (AFP) surveillance in support of polio eradication initiatives.

High occurrence of hepatitis E virus in samples from wastewater treatment plants in Switzerland and comparison with other enteric viruses

Hepatitis E virus (HEV) is responsible for many enterically transmitted viral hepatitides around the world. It is currently one of the waterborne diseases of global concern. In industrialized countries, HEV appears to be more common than previously thought, even if it is rarely virulent. In Switzerland, seroprevalence studies revealed that HEV is endemic, but no information was available on its environmental spread. The aim of this study was to investigate -using qPCR- the occurrence and concentration of HEV and three other viruses (norovirus genogroup II, human adenovirus-40 and porcine adenovirus) in influents and effluents of 31 wastewater treatment plants (WWTPs) in Switzerland. Low concentrations of HEV were detected in 40 out of 124 WWTP influent samples, showing that HEV is commonly present in this region. The frequency of HEV occurrence was higher in summer than in winter. No HEV was detected in WWTP effluent samples, which indicates a low risk of environmental contamination. HEV occurrence and concentrations were lower than those of norovirus and adenovirus. The autochthonous HEV genotype 3 was found in all positive samples, but a strain of the non-endemic and highly pathogenic HEV genotype I was isolated in one sample, highlighting the possibility of environmental circulation of this genotype. A porcine fecal marker (porcine adenovirus) was not detected in HEV positive samples, indicating that swine are not the direct source of HEV present in wastewater. Further investigations will be necessary to determine the reservoirs and the routes of dissemination of HEV.

Bayesian Modeling of Enteric Virus Density in Wastewater Using Left-Censored Data

Stochastic models are used to express pathogen density in environmental samples for performing microbial risk assessment with quantitative uncertainty. However, enteric virus density in water often falls below the quantification limit (non-detect) of the analytical methods employed, and it is always difficult to apply stochastic models to a dataset with a substantially high number of non-detects, i.e., left-censored data. We applied a Bayesian model that is able to model both the detected data (detects) and non-detects to simulated left-censored datasets of enteric virus density in wastewater. One hundred paired datasets were generated for each of the 39 combinations of a sample size and the number of detects, in which three sample sizes (12, 24, and 48) and the number of detects from 1 to 12, 24 and 48 were employed. The simulated observation data were assigned to one of two groups, i.e., detects and non-detects, by setting values on the limit of quantification to obtain the assumed number of detects for creating censored datasets. Then, the Bayesian model was applied to the censored datasets, and the estimated mean and standard deviation were compared to the true values by root mean square deviation. The difference between the true distribution and posterior predictive distribution was evaluated by Kullback-Leibler (KL) divergence, and it was found that the estimation accuracy was strongly affected by the number of detects. It is difficult to describe universal criteria to decide which level of accuracy is enough, but eight or more detects are required to accurately estimate the posterior predictive distributions when the sample size is 12, 24, or 48. The posterior predictive distribution of virus removal efficiency with a wastewater treatment unit process was obtained as the log ratio posterior distributions between the posterior predictive distributions of enteric viruses in untreated wastewater and treated wastewater. The KL divergence between the true distribution and posterior predictive distribution of virus removal efficiency also depends on the number of detects, and eight or more detects in a dataset of treated wastewater are required for its accurate estimation.

Studies on the bacteriological qualities of the Buffalo River and three source water dams along its course in the Eastern Cape Province of South Africa

The Buffalo River and its dams are major surface water sources used for fresh produce irrigation, raw water abstraction and recreation in parts of the Eastern Cape Province in South Africa. Over a 12-month period (August 2010 to July 2011), we assessed the bacteriological qualities of water from the river and 3 source water dams along its course. Faecal indicator bacteria (FIB), including total coliform (TC), faecal coliform (FC) and enterococci (ENT) counts, were high and ranged as follows: 1.9 × 10(2)-3.8 × 10(7), 0-3.0 × 10(5) and 0-5.3 × 10(5) cfu/100 ml for TC, FC and ENT, respectively. Significantly (P<0.05) higher concentrations of FC and ENT were observed at the sampling sites located at the lower reaches of the river compared to the upper reaches, and at Bridle Drift Dam compared to the other two dams. FIB counts mostly exceeded the recommended maximum values suggested by national and international guidelines for safe fresh produce irrigation, domestic applications, full-contact recreation and livestock watering. These results show that the bacteriological qualities of the Buffalo River and dams were poor, and suggest that sewage was dumped into the Buffalo River during the study period. Urban runoffs and effluents of wastewater treatment plants appear to be important sources of faecal contamination in the river. We conclude that these water bodies represent significant public health hazards. Provision of adequate sanitary infrastructure will help prevent source water contamination, and public health education aimed at improving personal, household and community hygiene is imperative.

Epidemiology and estimated costs of a large waterborne outbreak of norovirus infection in Sweden

A large outbreak of norovirus (NoV) gastroenteritis caused by contaminated municipal drinking water occurred in Lilla Edet, Sweden, 2008. Epidemiological investigations performed using a questionnaire survey showed an association between consumption of municipal drinking water and illness (odds ratio 4·73, 95% confidence interval 3·53–6·32), and a strong correlation between the risk of being sick and the number of glasses of municipal water consumed. Diverse NoV strains were detected in stool samples from patients, NoV genotype I strains predominating. Although NoVs were not detected in water samples, coliphages were identified as a marker of viral contamination. About 2400 (18·5%) of the 13 000 inhabitants in Lilla Edet became ill. Costs associated with the outbreak were collected via a questionnaire survey given to organizations and municipalities involved in or affected by the outbreak. Total costs including sick leave, were estimated to be ∼8 700 000 Swedish kronor (∼€0·87 million).

Evaluation of commercial kits for the extraction and purification of viral nucleic acids from environmental and fecal samples

The extraction and purification of nucleic acids is a critical step in the molecular detection of enteric viruses from environmental or fecal samples. In the present study, the performance of three commercially available kits was assessed: the MO BIO PowerViral Environmental DNA/RNA Isolation kit, the Qiagen QIAamp Viral RNA Mini kit, and the Zymo ZR Virus DNA/RNA Extraction kit. Viral particles of adenovirus 2 (AdV), murine norovirus (MNV), and poliovirus type 1 (PV1) were spiked in molecular grade water and three different types of sample matrices (i.e., biosolids, feces, and surface water concentrates), extracted with the kits, and the yields of the nucleic acids were determined by quantitative PCR (qPCR). The MO BIO kit performed the best with the biosolids, which were considered to contain the highest level of inhibitors and provided the most consistent detection of spiked virus from all of the samples. A qPCR inhibition test using an internal control plasmid DNA and a nucleic acid purity test using an absorbance at 230 nm for the nucleic acid extracts demonstrated that the MO BIO kit was able to remove qPCR inhibitors more effectively than the Qiagen and Zymo kits. These results suggest that the MO BIO kit is appropriate for the extraction and purification of viral nucleic acids from environmental and clinical samples that contain high levels of inhibitors.

Quantitative detection and characterization of human adenoviruses in the Buffalo River in the Eastern Cape Province of South Africa

Buffalo River is an important water resource in the Eastern Cape Province of South Africa. Over a 1-year period (August 2010-July 2011), we assessed the prevalence of human adenoviruses (HAdVs) at a total of 6 sites on the river and three dams along its course. HAdVs were detected by real-time quantitative PCR in about 35 % of the samples with concentrations ranging from 1.2 × 10(1) genome copies (GC)/l to 4.71 × 10(3) GC/l. HAdVs were detected at 5 of the 6 sampling sites with the detection rate ranging from 8.3 % at Rooikrantz Dam to 92 % at Parkside. The HAdV concentrations across the sampling sites were as follows: Parkside (3.25 × 10(2)-4.71 × 10(3) GC/); King William's Town (1.02 × 10(2)-4.56 × 10(3) GC/l); and Eluxolzweni (1.17 × 10(2)-3.97 × 10(2) GC/l). Significantly (P < 0.05) higher concentrations were detected at the non-dam sites compared to the dam sites. A very low mean concentration of 1.86 × 10(1) HAdV GC/l was observed at Bridle Drift Dam. While HAdVs were detected only once at Rooikrantz Dam (1.74 × 10(1) GC/l), no HAdV was detected at Maden Dam. Epidemiologically important serotypes, Ad40/41, constituted 83.3 %, while Ad21 made up 16.7 % of the all HAdVs detected and were characterized by qualitative PCR. The Buffalo River presents a public health risk heightened by the presence of Ad 40/41 and Ad21. Our results make imperative the need for assessing water sources for viral contamination in the interest of public health. This work is a significant contribution to the molecular epidemiology of adenoviruses and to the best of our knowledge this is the first report on detection of enteric virus from surface waters in the Eastern Cape.

Quantitative RT-PCR detection of hepatitis A virus, rotaviruses and enteroviruses in the Buffalo River and source water dams in the Eastern Cape Province of South Africa

Human enteric viruses (HEntVs) are a major cause of water-related diseases. The prevalence of hepatitis A virus (HAV), rotaviruses (RoV) and enteroviruses (EnV) in Buffalo River waters was assessed quantitatively over a period of 12 months (August 2010 to July 2011). Seventy-two samples were collected from six sites, including three dams, and concentrated using the adsorption-elution method. Viral RNA was extracted using a commercial kit, and the viruses were quantified by real-time quantitative reverse transcriptase PCR (RT-qPCR). Two or more viruses were detected in 12.5% of the samples. HAV was detected in 43.1% of the samples and in significantly (p < 0.05) varying concentrations of 1.5 × 10(1)–1.9 × 10(5) genome copies/L compared to RoV and EnV, while RoVs were detected in 13.9% of samples, with concentrations ranging from 2.5 × 10(1)–2.1 × 10(3) genome copies/L, and EnV were detected in 9.7% of the samples, with concentrations ranging from 1.3 × 10(1)–8.6 × 10(1) genome copies/L. Only HAV was detected at all the sites, with the Bridle Drift Dam recording significantly higher (p < 0.05) concentrations. The presence of enteric viruses in Buffalo River may constitute public health risks and the incidence of HAV at all the sites could reflect both the epidemiological status of hepatitis A and HAV persistence in the water environments.

Reliability of non-culturable virus monitoring by PCR-based detection methods in environmental waters containing various concentrations of target RNA

Owing to the lack of practical cell culture system for human noroviruses (HuNoV), various detection methods based on conventional reverse transcription-PCR (RT-PCR) and the quantitative real-time PCR have been major tools for monitoring environmental water safety. In this study, we showed that the proportion of water sample concentrates used for one-step RT-PCR significantly influences false-negative findings of the non-culturable viruses. In total, 59 archived samples of previously analyzed water concentrates were reexamined for HuNoV RNA by the one-step RT-PCR and semi-nested PCR. Using new aliquots for RNA extraction for every trial, up to 20 PCR trials were performed for each archive to determine whether the crosscheck results supported the previous determinations. We reconfirmed that 27.6% (8/29) of the samples were HuNoV-positive samples: 6.7% (1/15) from groundwater, 33.3% (3/9) from river water, and 80% (4/5) from treated sewage effluent (TSE). These results corresponded to the ratio of previously negative HuNoV samples now identified as positive (8/30): 6.7% (1/15) from groundwater, 20% (1/5) from river water, and 60% (6/10) from TSE. To elucidate the cause of these results, 16 different concentrations of murine norovirus (MNV) RNA (from 2×10(2) to 8×10(3) copies, divided into 10 tubes for each concentration) were subjected to one-step RT-PCR. The detection frequency and reproducibility decreased sharply when the number of MNV RNA copies fell below threshold levels. These observations suggest that the proportion of water concentrate used for PCR-based detection should be considered carefully when deciding viral presence in certain types of environmental water, particularly in regard with legal controls.

High variety of known and new RNA and DNA viruses of diverse origins in untreated sewage

Deep sequencing of untreated sewage provides an opportunity to monitor enteric infections in large populations and for high-throughput viral discovery. A metagenomics analysis of purified viral particles in untreated sewage from the United States (San Francisco, CA), Nigeria (Maiduguri), Thailand (Bangkok), and Nepal (Kathmandu) revealed sequences related to 29 eukaryotic viral families infecting vertebrates, invertebrates, and plants (BLASTx E score, <10(-4)), including known pathogens (>90% protein identities) in numerous viral families infecting humans (Adenoviridae, Astroviridae, Caliciviridae, Hepeviridae, Parvoviridae, Picornaviridae, Picobirnaviridae, and Reoviridae), plants (Alphaflexiviridae, Betaflexiviridae, Partitiviridae, Sobemovirus, Secoviridae, Tombusviridae, Tymoviridae, Virgaviridae), and insects (Dicistroviridae, Nodaviridae, and Parvoviridae). The full and partial genomes of a novel kobuvirus, salivirus, and sapovirus are described. A novel astrovirus (casa astrovirus) basal to those infecting mammals and birds, potentially representing a third astrovirus genus, was partially characterized. Potential new genera and families of viruses distantly related to members of the single-stranded RNA picorna-like virus superfamily were genetically characterized and named Picalivirus, Secalivirus, Hepelivirus, Nedicistrovirus, Cadicistrovirus, and Niflavirus. Phylogenetic analysis placed these highly divergent genomes near the root of the picorna-like virus superfamily, with possible vertebrate, plant, or arthropod hosts inferred from nucleotide composition analysis. Circular DNA genomes distantly related to the plant-infecting Geminiviridae family were named Baminivirus, Nimivirus, and Niminivirus. These results highlight the utility of analyzing sewage to monitor shedding of viral pathogens and the high viral diversity found in this common pollutant and provide genetic information to facilitate future studies of these newly characterized viruses.

Molecular detection of three gastroenteritis viruses in urban surface waters in Beijing and correlation with levels of fecal indicator bacteria

To assess the presence of three gastroenteritis viruses responsible for human acute gastroenteritis in surface water, a 1-year study was carried out in the city of Beijing, China. A total of 108 urban surface water samples were collected from nine collection sites which were defined with a global positioning system in rivers or lakes from September 2006 to August 2007. The water samples were subjected to virus concentration using an HA electronegative filter, followed by polymerase chain reaction (PCR) for rotavirus (RV) astrovirus (AV), and norovirus (NV). It showed that the number of viruses detected in water samples from different sites was variable, totaling 63 virus strains, with rotavirus (48.1%) verified as the most prevalent detected, followed by astrovirus (AV, 5.6%), and norovirus (NV, 4.6%). RV was also quantified by real-time PCR and the concentration of RV ranged from 0 to 18.27 genome copies·L(-1). And the distributions of RV in surface water were abundant in cold weather (from September to February) while less prevailing in warm weather (from March to August). The high detection rate of RV we encountered in this study provided convincing evidence that RV circulated at a certain frequency in the Beijing population. There was no statistically significant correlation between RV levels and both fecal coliform (R (2) = 0.02) and Enterococcus faecalis (R (2) = 0.02) densities. Our study suggests prolonged virus persistence in aquatic environments and emphasizes the enteric virus group as the most reliable for environmental monitoring.

Recovery comparison of two virus concentration methods from wastewater using cell culture and real-time PCR

Enteric viruses are shed in the feces and may be present in environmental waters. Their detection in wastewater, even at low concentration, is a major challenge. In this study, recoveries of Echovirus 7 (EV7), virions and RNA in wastewater, using virus concentration methods were determined to evaluate the detection of infectious viruses and the possibility of recovering viral genomes. Two virus concentration methods, PEG precipitation method and two-phase separation method, were applied to recovery experiments of EV7-virions from wastewater, in parallel with recovery experiments of EV7 RNA. The titration of EV7 virions was carried out by cell culture using human rhabdomyosarcoma tumor tissue and the EV7 RNA quantification was performed by real-time PCR. The mean recovery yields of EV7 virions using the PEG precipitation method and the two-phase separation method were 78.5 ± 10.99 and 83.1 ± 0.28 %, respectively. Besides, EV7 RNA recoveries obtained using the PEG precipitation method were four times higher than those using the two-phase separation method. According to our results, the two methods enable to concentrate both infectious viruses and viral genomes. Moreover, considering the protocol time and cost together with the ratio of the EV7 virion recovery to the EV7 RNA recovery, the two-phase separation method (83.1/2.71 %, or 30.6) seems to be more appropriate for selective concentration of viral virions than the PEG precipitation method (78.5/10.33 %, or 7.6).

New approaches for enhanced detection of enteroviruses from Hawaiian environmental waters

Health risks associated with sewage-contaminated recreational waters are of important public health concern. Reliable water monitoring systems are therefore crucial. Current recreational water quality criteria rely predominantly on the enumeration of bacterial indicators, while potentially dangerous viral pathogens often remain undetected. Human enteric viruses have been proposed as alternative indicators; however, their detection is often hindered by low viral concentrations present in the environment. Reported here are novel and effective laboratory protocols for viral concentration and highly sensitive and optimized RT-PCR for the efficient detection of enteroviruses, an important enteric virus subset, in Hawaiian environmental waters. Eighteen published enterovirus primer pairs were comparatively evaluated for detection sensitivity. The primer set exhibiting the lowest detection limit under optimized conditions, EQ-1/EQ-2, was validated in a field survey of 22 recreational bodies of water located around the island of Oahu, Hawaii. Eleven sites tested positive for enterovirus, indicating fecal contamination at these locations. As an additional means of viral concentration, shellfish were collected from 9 sample sites and subjected to dissection, RNA extraction, and subsequent RT-PCR. Shellfish tissue from 6 of 9 sites tested positive for enterovirus. The techniques implemented here are valuable resources to aid accurate reflection of microbial contamination in Hawaii’s environmental waters.

Microbiological and physicochemical analysis of the coastal waters of southern Brazil

The aim of this study was to assess the impact of sewage discharge on coastal waters by evaluating the influence of physicochemical parameters on the presence of enteric microorganisms in seawater samples collected from 11 beaches in Florianopolis, Santa Catarina, Brazil, over a one-year period (August 2009 to July 2010). Samples were assessed for the presence of human adenoviruses (HAdV), polyomavirus (JCPyV), hepatitis A virus (HAV), and noroviruses (HuNoV GI and GII). Escherichia coli and physicochemical parameters (salinity, temperature, pH and dissolved oxygen) were also evaluated. From the 132 samples analyzed, 55% were positive for HAdV, 51.5% for HAV, 7.5% for HuNoV GI, 4.5% for HuNoV GII, and 3% for JCPyV. E. coli levels ranged from 8 to 1325 CFU/100mL at all sites. The overall results highlight the problem of sewage discharge into coastal waters and confirm that there is no correlation between viral presence and bacterial contamination.

Adsorption characteristics of an enteric virus-binding protein to norovirus, rotavirus and poliovirus

BACKGROUND

Water contamination with human enteric viruses has posed human health risks all over the world. Reasonable and facile methodologies for recovering and quantifying infectious enteric viruses in environmental samples are needed to address the issues of waterborne viral infectious diseases. In this study, a bacterial protein that has a binding capability with several enteric viruses is discovered, and its binding characteristics were investigated for utilizing it as a viral adsorbent in virus recovery and detection technologies.

RESULTS

A gene of an enteric virus-binding protein (EVBP), derived from a monomer of a bacterial chaperon protein GroEL, was successfully acquired from a genomic DNA library of activated sludge microorganisms with nested PCR. Equilibrium dissociation constants between EVBP and norovirus-like particles (NoVLPs) of genotypes GI.7 and GII.4, estimated with quartz crystal microbalance method, were 240 and 210 nM, respectively. These values of equilibrium dissociation constant imply that the binding affinity between EVBP and NoVLPs is 1 to 3-log weaker than that in general antigen-antibody interactions, but about 2-log stronger than that in weak specific interactions of proteins with cations and organic polymers. The adsorptions of EVBP to norovirus, group A rotavirus and poliovirus type 1 were found to be significant in enzyme-linked immunosorbent assay. Meanwhile, the binding of native GroEL tetradecamer to viral particles was weaker than that of EVBP, presumably because of a steric hindrance. The small molecule of EVBP could have an advantage in the access to the surface of viral particles with rugged structure.

CONCLUSIONS

EVBP that has a broad binding spectrum to enteric viruses was newly discovered. The broad binding characteristic of EVBP would allow us to utilize it as a novel adsorbent for detecting diverse enteric viruses in clinical and environmental samples.

Challenges in environmental detection of human viral pathogens

There is substantial potential for human exposure to viruses in environmental matrixes. Identification of virally contaminated environmental reservoirs requires assays with sufficient sensitivity to detect low copy numbers of viral targets. However, low detection sensitivity frequently requires sample concentration during which inhibitors to downstream assays co-isolate with desired target. Conventional detection assays (e.g., cell culture, polymerase chain reaction) require a priori selection of appropriate cell lines or primers and probes based on the viruses anticipated to be present in the sample. This can underestimate exposure risks by excluding unidentified or unknown virus. Emerging methods including nonspecific adsorption/elution, filtration, and total nucleic acid sequencing, that are capable of concentrating, purifying, and detecting total virus and/or total virus nucleic acid will aid in estimates of exposure risk, source tracking, intervention efficacy, and evaluation of virus fate and transport. Development and implementation of novel virus detection techniques must integrate quality assurance guidelines to validate results and provide opportunities for interstudy comparison.

One year environmental surveillance of rotavirus specie A (RVA) genotypes in circulation after the introduction of the Rotarix® vaccine in Rio de Janeiro, Brazil

Rotavirus specie A (RVA) infection is the leading cause of severe acute diarrhea among young children worldwide. To reduce this major RVA health impact, the Rotarix® vaccine (GlaxoSmithKline, Rixensart, Belgium) was introduced in the Brazilian Expanded Immunization Program in March 2006 and became available to the entire birth cohort. The aim of this study was to evaluate the spread of RVA in the environment after the introduction of Rotarix® in Brazil. For this purpose, a Wastewater Treatment Plant (WTP) in Rio de Janeiro was monitored for one year to detect, characterize and discriminate RVA genotypes and identify possible circulation of vaccine strains. Using TaqMan® quantitative PCR (qPCR), RVA was detected in 100% (mean viral loads from 2.40×10(5) to 1.16×10(7) genome copies (GC)/L) of sewage influent samples and 71% (mean viral loads from 1.35×10(3) to 1.64×10(5)GC/L) of sewage effluent samples. The most prevalent RVA genotypes were P[4], P[6] and G2, based on VP4 and VP7 classification. Direct nucleotide sequencing (NSP4 fragment) and restriction enzyme digestion (NSP3) analysis did not detect RVA vaccine-like strains from the sewage samples. These data on RVA detection, quantification and molecular characterization highlight the importance of environmental monitoring as a tool to study RVA epidemiology in the surrounding human population and may be useful on ongoing vaccine monitoring programs, since sewage may be a good screening option for a rapid and economical overview of the circulating genotypes.

Norovirus infectivity in humans and persistence in water

To examine the long-term infectivity of human norovirus in water, 13 study subjects were challenged at different time points with groundwater spiked with the prototype human norovirus, Norwalk virus. Norwalk virus spiked in groundwater remained infectious after storage at room temperature in the dark for 61 days (the last time point tested). The Norwalk virus-seeded groundwater was stored for 1,266 days and analyzed, after RNase treatment, by reverse transcription-quantitative PCR (RT-qPCR) to detect Norwalk virus RNA contained within intact capsids. Norwalk virus RNA within intact capsids was detected in groundwater for 1,266 days, with no significant log(10) reduction throughout 427 days and a significant 1.10-log(10) reduction by day 1266. Purified Norwalk virus RNA (extracted from Norwalk virus virions) persisted for 14 days in groundwater, tap water, and reagent-grade water. This study demonstrates that Norwalk virus in groundwater can remain detectable for over 3 years and can remain infectious for at least 61 days. (ClinicalTrials.gov identifier NCT00313404.).

Environmental surveillance. An additional/alternative approach for virological surveillance in Greece?

The detection of viruses in the sewage of an urban city by nucleic acid amplification techniques allows the identification of the viral strains that are circulating in the community. The aim of the study was the application of such detection which gives useful data on the distribution, spread, and frequency of these viruses, supporting epidemiological studies of the related viral infections. A two year (2007–2009) survey was conducted in order to evaluate the presence of human adenoviruses (hAdV), hepatitis A viruses (HAV), hepatitis E viruses (HEV), noroviruses (NoV), and human polyomaviruses (hPyV) in sewage samples collected from the inlet of a municipal biological wastewater treatment plant located in southwestern Greece. PCR methods were used for this survey. In total, viruses have been detected in 87.5% (42/48) of the analyzed sewage samples. Analytically, DNA viruses, hAdVs and hPyVs have been detected in 45.8% (22/48) and 68.8% (33/48) of the samples, respectively. As it concerns RNA viruses, HAV was detected in 8.3% (4/48), NoVs in 6.3% (3/48), while HEV has not been detected at all. After sequencing, AdVs were typed as Ad8, Ad40 and Ad41, while both JC and BK hPyVs have been recognized. All NoVs have been identified as GII4, while HAV was typed as genotype IA. Similar long-term studies could be undertaken in countries such as Greece in order to offer a valuable and complementary tool to current problematic epidemiological surveillance systems. This study demonstrates the advantages of environmental surveillance as a tool to determine the epidemiology of viruses circulating in a given community. To our knowledge this was the first of its kind study performed in Greece in order to establish this new way of surveillance.

Survival of adenovirus types 2 and 41 in surface and ground waters measured by a plaque assay

To manage artificial recharge systems, it is necessary to understand the inactivation process of microorganisms within aquifers so that requirements regarding storage times and treatment strategies for ground and surface waters can be developed and modeled to improve water management practices. This study was designed to investigate the survival of representative adenoviruses in surface- and groundwaters using a cell culture plaque assay with human lung carcinoma cells (A549) to enumerate surviving viruses. Adenovirus types 2 (Ad2) and 41 (Ad41) were seeded into 50 mL of three sterilized surface waters and groundwaters, and incubated at 10 and 19 °C for up to 301 days. Concentrations of Ad2 and Ad41 were relatively stable in all waters at 10 °C for at least 160 days and in some instances up to 301 days. At 19 °C, virus concentrations were reduced by 99.99% (4 log) after 301 days in surface water. There was approximately 90% (1 log) reduction of both viruses at 19 °C after 160 days of incubation in groundwater samples. There was no overall difference in survival kinetics in surface waters compared to groundwaters. The relatively high stability and long-term survival of adenoviruses in environmental waters at elevated temperatures should be considered in risk assessment models and drinking water management strategies.

Molecular detection of multiple viral targets in untreated urban sewage from Greece

Background

Urban sewage virological analysis may produce important information about the strains that cause clinical and subclinical infections in the population, thus supporting epidemiological studies.

Methods

In the present study, a twenty one-month survey (November 2007 to July 2009) was conducted in order to evaluate the presence of human adenoviruses (hAdV), hepatitis A viruses (HAV), hepatitis E viruses (HEV), Noroviruses (NoV), and human Polyomaviruses (hPyV) in untreated sewage samples collected from the inlet of Patras' municipal biological wastewater treatment plant, located in southwestern Greece. Nucleic acid amplification techniques were applied for viral nucleic acid detection. Positive samples were confirmed by sequencing and comparative phylogenetic analysis was performed on the isolated viral strains.

Results

In total, viruses were detected in 87.5% (42/48) of sewage samples. AdVs, PyVs, HAV, and NoVs were detected in 45.8% (22/48), 68.8% (33/48), 8.3% (4/48), and 6.3% (3/48) of the samples collected from the plant's inlet, while HEV was not detected at all. Adenovirus types 8 (Ad8), 40 (Ad40) and 41 (Ad41) were recognized, while JC and BK polyomaviruses were recorded. Noroviruses were identified as GII.4. HAV was typed as genotype IA.

Conclusions

Our study demonstrates the advantages of environmental surveillance as a tool to elucidate the molecular epidemiology of community circulating viruses. We underline the need of environmental surveillance programs in countries such as Greece with inadequate and problematic epidemiological surveillance system and no environmental surveillance system currently in action.

The detection of enteric viruses in selected urban and rural river water and sewage in Kenya, with special reference to rotaviruses

AIM

To determine the occurrence of eight human enteric viruses in surface water and sewage samples from different geographical areas in Kenya.

METHODS AND RESULTS

Enteric viruses were recovered from the water and sewage sources by glass-wool adsorption elution and/or polyethylene glycol/NaCl precipitation and detected by singleplex real-time and conventional PCR and reverse transcriptase-PCR assays. One or more enteric viruses were detected in nearly all sewage and river water samples except the urban Mbagathi River. The VP7 (G types) and the VP4 (P types) of the rotaviruses (RV) were characterized by multiplex nested PCR methods. The G and P types could be determined in 95·5% of the RV strains, respectively. Mixed G types were detected with G12 and G1 predominating, and unusual G types, G5 and G10, were present. P[4] predominated in the urban Karen sewage samples, while P[8] predominated in the urban and rural streams.

CONCLUSIONS

The high prevalence of RVs in surface water highlights the importance of assessing the water sources used for domestic purposes for viral contamination.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrates the benefit of environmental surveillance as an additional tool to determine the epidemiology of RVs and other enteric viruses circulating in a given community.

Molecular diagnostic assays for detection of viral respiratory pathogens in institutional outbreaks

Outbreaks of viral respiratory disease in institutions may be associated with high morbidity and mortality, depending upon the viral etiology and the age and immune status of the affected patients. Control of outbreaks may include isolation and/or cohorting, and prohylaxis or treatment with specific antiviral agents may be indicated, all dependent upon the specific cause of the outbreak. Conventional methods of viral diagnosis detect only a limited number of the viruses that are known to cause outbreaks. The availability of sensitive and specific molecular assays has facilitated rapid diagnosis of a wider range of viruses from respiratory outbreaks. Molecular methods have distinct advantages over conventional methods, including the ability to rapidly develop assays for emerging viruses and new variants of existing viruses. In addition, molecular testing allows rapid detection of resistance to antiviral agents or mutations leading to increased virulence. However, high-throughput molecular testing requires batch processes that may compromise the ability to respond quickly to urgent testing demands.

Norovirus as a foodborne disease hazard

Norovirus (NoV) is the most common cause of infectious gastroenteritis in the world. Gastroenteritis caused by bacterial and parasitic pathogens is commonly linked to food sources, but the link between NoV and contaminated foods has been more difficult to establish. Even when epidemiological information indicates that an outbreak originated with food, the presence of NoV in the suspect product may not be confirmed. If food is found to contain a common strain of NoV that circulates widely in the community, it is not possible to use strain typing to link the contamination to patient cases. Although food is certainly implicated in NoV spread, there are additional person-to-person and fomite transmission routes that have been shown to be important. NoV has an extremely low infectious dose, is stable in the environment, and resists disinfection. Cell culture methods are not available, so viability cannot be determined. Finally, many NoV outbreaks originate with when an infected food handler contaminates ready-to-eat food, which can be interpreted as foodborne or person-to-person transmission. This review will discuss both the physical characteristics of NoVs and the available epidemiological information with particular reference to the role of foods in NoV transmission.

Quantification and molecular characterization of enteric viruses detected in effluents from two hospital wastewater treatment plants

Hospital wastewater has been described as an important source of spreading pathogenic microorganisms in the environment. However, there are few studies reporting the presence and concentrations of gastroenteric viruses and hepatitis A viruses in these environmental matrices. The aim of this study was to assess the contamination by viruses responsible for acute gastroenteritis and hepatitis derived from hospital wastewater treatment plants (WWTPs). Rotavirus A (RV-A), human adenoviruses (HAdV), norovirus genogroup I and II (NoV GI/GII) and hepatitis A viruses (HAV) were detected and quantified in sewage samples from two WWTPs located in Rio de Janeiro (Brazil) that operates different sewage treatments. WWTP-1 uses an Upflow Anaerobic Sludge Blanket (UASB reactor) and three serial anaerobic filters while WWTP-2 uses aerobic processes, activated sludge with extended aeration and final chlorination of the effluents. Viruses' detection was investigated by using conventional PCR/RT-PCR, quantitative real-time PCR (qPCR) and partial sequencing of the genome of the viruses detected. Rate of viruses detection ranged from 7% (NoV GI in WWTP-1) to 95% (RV-A in WWTP-2) and genome from all viruses were detected. The most prevalent genotypes were RV-A SG I, HAdV species D and F, NoV GII/4 and HAV subgenotype IA. Mean values of viral loads (genome copies (GC)/ml) obtained in filtered effluents from anaerobic process was 1.9 × 10(3) (RV-A), 2.8 × 10(3) (HAdV) and 2.4 × 10(3) (NoV GII). For chlorinated effluents from activated sludge process, the mean values of viral loads (GC/ml) was 1.2 × 10(5) (RV-A), 1.4 × 10(3) (HAdV), 8.1 × 10(2) (NoV GII) and 2.8 × 10(4) (HAV). Data on viral detection in treated effluents of hospital WWTPs confirmed the potential for environmental contamination by viruses and could be useful to establish standards for policies on wastewater management.

Improved detection and quantitation of norovirus from water

Norovirus is associated commonly with human sewage and is responsible for numerous cases of waterborne and foodborne gastroenteritis every year. Assays using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) have been developed for norovirus, however, accurate detection and quantitation remain problematic owing to a lack of suitable positive controls. To improve enumeration of norovirus genomes from water, a synthetic norovirus genogroup II quantitation standard and competitive internal positive control were developed. The quantitation standard demonstrates identical amplification efficiency as wildtype norovirus and can be used as a viral surrogate in labs with restricted access to norovirus. The internal control quantifies sample inhibition, allowing for accurate quantitation of norovirus from complex environmental samples. Seawater samples spiked with sewage or bird guano were evaluated using the norovirus assay as part of a methods comparison study. Inhibition was detected in nine of 36 (25%) samples, two of which proved to be positive upon re-analysis. Results support the specificity of this assay for human-source (sewage) fecal contamination. Overall, use of this quantitation standard and internal control signify a great advance over traditional positive controls and suggest that molecular techniques for viral analysis could become standardized for routine water quality monitoring.

New perspectives in monitoring drinking water microbial quality

The safety of drinking water is evaluated by the results obtained from faecal indicators during the stipulated controls fixed by the legislation. However, drinking-water related illness outbreaks are still occurring worldwide. The failures that lead to these outbreaks are relatively common and typically involve preceding heavy rain and inadequate disinfection processes. The role that classical faecal indicators have played in the protection of public health is reviewed and the turning points expected for the future explored. The legislation for protecting the quality of drinking water in Europe is under revision, and the planned modifications include an update of current indicators and methods as well as the introduction of Water Safety Plans (WSPs), in line with WHO recommendations. The principles of the WSP approach and the advances signified by the introduction of these preventive measures in the future improvement of dinking water quality are presented. The expected impact that climate change will have in the quality of drinking water is also critically evaluated.

Detection of rotavirus A in sewage samples using multiplex qPCR and an evaluation of the ultracentrifugation and adsorption-elution methods for virus concentration

Group A rotaviruses (RV-A) are the most common agents of viral gastroenteritis in children worldwide. The goal of this study was to compare two different methods to concentrate RV-A from sewage samples and to improve the detection and quantification of RV-A using a multiplex quantitative PCR assay with an internal control. Both RV-A and the internal control virus, bacteriophage PP7, were seeded into wastewater and then concentrated using either an ultrafiltration-based adsorption-elution protocol or an ultracentrifugation-based protocol. Real time multiplex quantitative PCR was used to quantify the purified RV-A and PP7, and the results of the multiplex assay were compared with the results of the monoplex assays. The ultracentrifugation-based method had a mean recovery rate of 47% (range: 34-60%), while the ultrafiltration-based adsorption-elution method had a mean recovery rate of 3.5% (range: 1.5-5.5%). These results demonstrate that ultracentrifugation is a more appropriate method for recovering RV-A from wastewater. This method together with the multiplex qPCR assay may be suitable for routine laboratory use.

Evaluation of HA negatively charged membranes in the recovery of human adenoviruses and hepatitis A virus in different water matrices

Human adenoviruses (HAdV) and hepatitis A virus (HAV) are shed in the faeces and consequently may be present in environmental waters, resulting in an increase in pathogen concentration that can affect water quality and human health. The aim of this study was to evaluate an adsorption-elution method which utilizes negatively charged membrane HA to determine the efficient recovery of HAdV and HAV from different water matrices and to combine this procedure with a qualitative molecular method (nested RT-PCR and nested PCR). The best efficiency recovery was achieved in distilled water and treated wastewater effluent (100%) for both viruses and in recreational lagoon water for HAV (100%). The efficiency recovery was 10% for HAdV and HAV in seawater and 10% for HAdV in lagoon water. The viral detection limit by nested PCR for HAV in water samples ranged between 20-0.2 FFU/mL and 250 and 25 TCID50/mL for HAdV. In conclusion, these results suggest that the HA negatively charged membranes vary their efficiency for recovery of viral concentration depending upon the types of both enteric viruses and water matrices.

Hepatitis A virus: serology and molecular diagnostics

The diagnosis of hepatitis A virus (HAV) infection is based on the detection of anti-HAV IgM. Shortcomings of this serological approach include the persistence of IgM after normalization of liver enzymes or its detection during polyclonal activation of the immune system due to unrelated viral infection or autoimmune diseases. Molecular diagnosis of HAV along with anti-HAV IgG avidity measurement are helpful in case of positive IgM where laboratory evidence of acute hepatitis is absent and there is no epidemiologic link to other cases. Molecular epidemiology allows us to determine whether viruses from different locations are related to each other and provides further understanding of viral epidemiology by identifying sources and transmission modes. It has been demonstrated that the rapid turnover of HAV strains in low-endemicity countries is caused by their introduction by travelers. Growing sequence databases allow for the identification of geographic origin of viral strains. Collaboration between surveillance laboratories, including database sharing, should be promoted for deeper investigation of outbreaks and improved prevention approaches.

Environmental surveillance and molecular characterization of human enteric viruses in tropical urban wastewaters

AIMS

To study the prevalence and genotypes of waterborne pathogenic viruses in urban wastewaters in the tropical region.

METHODS AND RESULTS

Viruses in wastewaters collected at three water reclamation plants in Singapore were studied by molecular methods. Over a 6-month sampling period, adenoviruses, astroviruses and both norovirus genogroups I (GI) and II (GII) were detected in 100% of the sewage and secondary effluent. Enteroviruses and hepatitis A viruses (HAV) were found in 94 and 78% of sewage, and 89 and 28% of secondary effluent, respectively. By using quantitative real-time PCR, estimated concentrations of astrovirus in the sewage were 1-2 orders of magnitude higher than those for adenovirus, noroviruses GI and GII. Genotyping of environmental isolates revealed multiple genotypes of GI and GII noroviruses. Coxsackieviruses A, astrovirus type 1 and adenovirus type 41 were prevalent. Norovirus GII/4 and coxsackievirus A24 isolates in wastewaters were closely related to respective outbreak strains isolated previously in Singapore.

CONCLUSIONS

This study showed the widespread occurrence of all tested enteric virus groups in urban wastewaters. Genetic diversity of astroviruses, enteroviruses and noroviruses in the tropical region was observed.

SIGNIFICANCE AND IMPACT OF THE STUDY

The high prevalence and great genetic diversity of human enteric viruses in urban wastewaters strongly supports the need of further comprehensive studies for evaluating the public health risk associated with viral pathogens in water environments.

Concentration of viruses from environmental waters using nanoalumina fiber filters

Human viral contamination in drinking and recreational water may persist for extensive periods of time and cause a significant health risk concern. The aim of this study is to evaluate a viral recovery method using a new electropositive charged nanoalumina filter and to compare results with the widely used negatively charged HAWP filter by Millipore Inc. The recovery of infectious recombinant adenovirus type 5 (rAd5) was tested using the Fluorescence-Activated Cell Sorting (FACS) assay, in parallel with viral genomes recovery assay by quantitative PCR (qPCR). The mean infectivity recoveries were 82-91% by nanoalumina filters eluted with 3% beef extract (BE, pH 6.0), and 78-90% by HAWP filters eluted with 3% BE (pH 9.0), respectively, from 1L of environmental samples seeded with 1 pfu/mL rAd5. The mean genome recoveries were 16-35% by nanoalumina filters eluted with BE (pH 6.0), and 29-66% by HAWP filters eluted with NaOH (pH 10.8) from different types of water, respectively. Water quality, concentration of viruses, filters, and elution buffers are factors that determine the viral recovery efficiencies. The nanoalumina filters also had higher filtration rates than HAWP filters for large volumes of environmental water samples (up to 10 L), thus, have an advantage in concentrating infectious viruses from environments without pre-filtration, adjusting pH or adding multivalent cations.

Comparison of different concentration methods for the detection of hepatitis A virus and calicivirus from bottled natural mineral waters

Viral contamination of drinking water is frequently reported as the primary source of gastroenteritis or hepatitis outbreaks. The presence of viruses at low concentration levels in most environmental water poses major analytical problems when determining their concentration. To evaluate the efficiency of different recovery methods of viral RNA from bottled water, a comparison was made of 2 positively and 2 negatively charged membranes that were used for absorbing and releasing HAV virus particles during the filtration of viral spiked bottled water. All the 4 membranes, regardless of charge and pore size, had low level viral recovery. The results show that a considerable number of the virus particles passed through the pores of the membranes instead of being trapped by the electrostatic charges. Two different procedures were then compared using 1.5L polyethylene bottles spiked with 10-fold serial dilutions of HAV and FCV. The first procedure included an ultrafiltration-based method followed by MiniMag RNA extraction, and the second an ultracentrifugation-based method followed by RNA extraction using QIAamp viral RNA mini kit. The ultracentrifugation-based method resulted in a better recovery of HAV and FCV when compared to the ultrafiltration-based method.

Frequent detection of highly diverse variants of cardiovirus, cosavirus, bocavirus, and circovirus in sewage samples collected in the United States

Untreated sewage samples from 12 cities in the United States were screened for the presence of recently characterized RNA and DNA viruses found at high prevalence in the stool specimens of South Asian children. Genetic variants of human cosaviruses and cardioviruses in the Picornaviridae family and of DNA circoviruses and human bocaviruses were detected, expanding the known genetic diversity and geographic range of these newly identified viruses. All four virus groups were detected in sewage samples of less than a milliliter from multiple U.S. cities. PCR screening of particle-protected viral nucleic acid in sewage samples could therefore rapidly establish the presence and determine the diversity of four newly described enteric viruses in large urban populations. More frequent and deeper sampling of viral nucleic acids in sewage samples could be used to monitor changes in the prevalence and genetic composition of these and other novel enteric viruses.

Pepper mild mottle virus as an indicator of fecal pollution

Accurate indicators of fecal pollution are needed in order to minimize public health risks associated with wastewater contamination in recreational waters. However, the bacterial indicators currently used for monitoring water quality do not correlate with the presence of pathogens. Here we demonstrate that the plant pathogen Pepper mild mottle virus (PMMoV) is widespread and abundant in wastewater from the United States, suggesting the utility of this virus as an indicator of human fecal pollution. Quantitative PCR was used to determine the abundance of PMMoV in raw sewage, treated wastewater, seawater exposed to wastewater, and fecal samples and/or intestinal homogenates from a wide variety of animals. PMMoV was present in all wastewater samples at concentrations greater than 1 million copies per milliliter of raw sewage. Despite the ubiquity of PMMoV in human feces, this virus was not detected in the majority of animal fecal samples tested, with the exception of chicken and seagull samples. PMMoV was detected in four out of six seawater samples collected near point sources of secondary treated wastewater off southeastern Florida, where it co-occurred with several other pathogens and indicators of fecal pollution. Since PMMoV was not found in nonpolluted seawater samples and could be detected in surface seawater for approximately 1 week after its initial introduction, the presence of PMMoV in the marine environment reflects a recent contamination event. Together, these data demonstrate that PMMoV is a promising new indicator of fecal pollution in coastal environments.

Pepper mild mottle virus as an indicator of fecal pollution

Accurate indicators of fecal pollution are needed in order to minimize public health risks associated with wastewater contamination in recreational waters. However, the bacterial indicators currently used for monitoring water quality do not correlate with the presence of pathogens. Here we demonstrate that the plant pathogen Pepper mild mottle virus (PMMoV) is widespread and abundant in wastewater from the United States, suggesting the utility of this virus as an indicator of human fecal pollution. Quantitative PCR was used to determine the abundance of PMMoV in raw sewage, treated wastewater, seawater exposed to wastewater, and fecal samples and/or intestinal homogenates from a wide variety of animals. PMMoV was present in all wastewater samples at concentrations greater than 1 million copies per milliliter of raw sewage. Despite the ubiquity of PMMoV in human feces, this virus was not detected in the majority of animal fecal samples tested, with the exception of chicken and seagull samples. PMMoV was detected in four out of six seawater samples collected near point sources of secondary treated wastewater off southeastern Florida, where it co-occurred with several other pathogens and indicators of fecal pollution. Since PMMoV was not found in nonpolluted seawater samples and could be detected in surface seawater for approximately 1 week after its initial introduction, the presence of PMMoV in the marine environment reflects a recent contamination event. Together, these data demonstrate that PMMoV is a promising new indicator of fecal pollution in coastal environments.

Viral and bacterial contamination in recreational waters: a case study in the Lisbon bay area

AIMS

To assess the presence of viral pathogens in bathing water samples and to evaluate the interdependency of bacterial indicator counts and viral detection.

METHODS AND RESULTS

Bathing water samples of 16 beaches collected along a Portuguese Coastal area were screened for the hepatitis A virus (HAV) and norovirus genogroup I (NVGI) using RT-PCR technique. Bacteriological water quality was also assessed, according to European regulations. HAV and NVGI were detected in 95% and 27% of the water samples, respectively, whereas bacteriological quality was good in all but one sample, according to current water quality regulations.

CONCLUSIONS

All water samples would be considered of excellent quality according to the most recent European regulations. No relationship between viral detection and regulatory-based bacterial indicators was found.

SIGNIFICANCE AND IMPACT OF THE STUDY

The current results reinforce the importance of increased surveillance for pathogenic viruses in bathing waters.