Frequency of hepatitis E and Hepatitis A virus in water sample collected from Faisalabad, Pakistan

Hepatitis E and Hepatitis A virus both are highly prevalent in Pakistan mainly present as a sporadic disease. The aim of the current study is to isolate and characterized the specific genotype of Hepatitis E virus from water bodies of Faisalabad, Pakistan. Drinking and sewage samples were qualitatively analyzed by using RT-PCR. HEV Genotype 1 strain was recovered from sewage water of Faisalabad. Prevalence of HEV and HAV in sewage water propose the possibility of gradual decline in the protection level of the circulated vaccine in the Pakistani population.

Assessing point-of-use ultraviolet disinfection for safe water in urban developing communities

Residents of urban developing communities often have a tap in their home providing treated and sometimes filtered water but its microbial quality cannot be guaranteed. Point-of-use (POU) disinfection systems can provide safe drinking water to the millions who lack access to clean water in urban communities. While many POU systems exist, there are several concerns that can lead to low user acceptability, including low flow rate, taste and odor issues, high cost, recontamination, and ineffectiveness at treating common pathogens. An ultraviolet (UV) POU system was constructed utilizing developing community-appropriate materials and simple construction techniques based around an inexpensive low-wattage, low pressure UV bulb. The system was tested at the bench scale to characterize its hydrodynamic properties and microbial disinfection efficacy. Hydraulically the system most closely resembled a plug flow reactor with minor short-circuiting. The system was challenge tested and validated for a UV fluence of 50 mJ/cm(2) and greater, over varying flow rates and UV transmittances, corresponding to a greater than 4 log reduction of most pathogenic bacteria, viruses, and protozoa of public health concern. This study presents the designed system and testing results to demonstrate the potential architecture of a low-cost, open-source UV system for further prototyping and field-testing.

A One Year Study on the Concentrations of Norovirus and Enteric Adenoviruses in Wastewater and A Surface Drinking Water Source in Norway

Enteric viruses transmitted via the faecal-oral route occur in high concentrations in wastewater and may contaminate drinking water sources and cause disease. In order to quantify enteric adenovirus and norovirus genotypes I and II (GI and GII) impacting a drinking source in Norway, samples of surface water (52), wastewater inlet (64) and outlet (59) were collected between January 2011 and April 2012. Samples were concentrated in two steps, using an electropositive disc filter and polyethylene glycol precipitation, followed by nucleic acid extraction and analysis by quantitative polymerase chain reaction. Virus was detected in 47/52 (90.4%) of surface water, 59/64 (92%) of wastewater inlet and 55/59 (93%) of wastewater outlet samples. Norovirus GI occurred in the highest concentrations in surface water (2.51e + 04) and adenovirus in wastewater (2.15e + 07). While adenovirus was the most frequently detected in all matrices, norovirus GI was more frequently detected in surface water and norovirus GII in wastewater. This study is the first in Norway to monitor both sewage and a drinking water source in parallel, and confirms the year-round presence of norovirus and adenovirus in a Norwegian drinking water source.

Effect of hydraulically reversible and hydraulically irreversible fouling on the removal of MS2 and φX174 bacteriophage by an ultrafiltration membrane

The effect of membrane fouling on the removal of enteric virus surrogates MS2 and φX174 bacteriophage by an ultrafiltration membrane was assessed under simulated full-scale drinking water treatment operating conditions. Filtration experiments of up to 8 days using either river or lake water ascertained how the membrane fouling layer affected virus removal. Organic carbon fractionation techniques identified potential foulants, including biopolymers, in the feed water and in the permeate. Hydraulically irreversible fouling could greatly improve the removal of both viruses at moderate and severe fouling conditions by up to 2.5 logs. Hydraulically reversible fouling increased virus removal only slightly, and increased removal of >0.5 log for both phage were only obtained under severe fouling conditions. The increase in virus removal due to irreversible and reversible fouling differed between the two water sources. As the degree of fouling increased, differences between the removal of the two phage decreased. Maintenance cleaning partially removed membrane foulants, however virus removal following maintenance cleaning was lower than that of the fouled membrane, it remained higher than that of the clean membrane.

The application of new molecular methods in the investigation of a waterborne outbreak of norovirus in Denmark, 2012

In December 2012, an outbreak of acute gastrointestinal illness occurred in a geographical distinct area in Denmark covering 368 households. A combined microbiological, epidemiological and environmental investigation was initiated to understand the outbreak magnitude, pathogen(s) and vehicle in order to control the outbreak. Norovirus GII.4 New Orleans 2009 variant was detected in 15 of 17 individual stool samples from 14 households. Norovirus genomic material from water samples was detected and quantified and sequencing of longer parts of the viral capsid region (>1000 nt) were applied to patient and water samples. All five purposely selected water samples tested positive for norovirus GII in levels up to 1.8×10⁴ genomic units per 200 ml. Identical norovirus sequences were found in all 5 sequenced stool samples and 1 sequenced water sample, a second sequenced water sample showed 1 nt (<0.1%) difference. In a cohort study, including 256 participants, cases were defined as residents of the area experiencing diarrhoea or vomiting onset on 12–14 December 2012. We found an attack rate of 51%. Being a case was associated with drinking tap-water on 12–13 December (relative risk = 6.0, 95%CI: 1.6–22) and a dose-response relation for the mean glasses of tap-water consumed was observed. Environmental investigations suggested contamination from a sewage pipe to the drinking water due to fall in pressure during water supply system renovations. The combined microbiological, epidemiological and environmental investigations strongly indicates the outbreak was caused by norovirus contamination of the water supply system.

Investigation and control of a Norovirus outbreak of probable waterborne transmission through a municipal groundwater system

During March 2011 an outbreak of gastroenteritis occurred in Santo Stefano di Quisquina, Agrigento, Sicily, Italy. Within two weeks 156 cases were identified among the 4,965 people living in the municipality. An epidemiological investigation was conducted to characterize the outbreak and target the control measures. A case was defined as a person developing diarrhea or vomiting during February 27-March 13, 2011. Stool specimens were collected from 12 cases. Norovirus (NoV) genotype GII.4 variant New Orleans 2009 was identified in stool samples from 11 of 12 cases tested (91.7%). Epidemiological investigations suggested a possible association with municipal drinking water consumption. Water samples from the public water system were tested for NoV and a variety of genotypes were detected during the first 3 months of surveillance, including GII.4 strains belonging to different variants from that involved in the gastroenteritis outbreak. Contamination of the well and springs supplying the public water network was eventually thought to be the source of the NoV contamination.

Human adenovirus (HAdV), human enterovirus (hEV), and genogroup A rotavirus (GARV) in tap water in southern Brazil

The effects of viral gastroenteritis are more devastating in children than in any other age category. Thus, children exposed to the consumption of low quality water are at an increased risk of infection, especially in regions where sanitation is inadequate. The present study aimed to provide a survey of the occurrence of representative enteric viruses: human adenovirus (HAdV), human enteroviruses (hEV), and genogroup A rotavirus (GARV) in tap water samples collected in public schools located at six municipalities of Rio Grande do Sul, southern Brazil. Seventy-three schools were included in the study and tap water samples were analyzed by conventional PCR for the presence of HAdV, hEV, and GARV genomes. hEV showed the highest detection rate (27.4%), followed by HAdV (23.3%), and GARV (16.4%). New approaches to water monitoring should be considered to promote a better water quality and reduce the risk of waterborne diseases, especially considering drinking water to be served to vulnerable individuals.

[Effects of algae and kaolinite particles on the survival of bacteriophage MS2]

In this study, Bacteriophage MS2, Kaolinite and Microcystis aeruginosa were selected as model materials for human enteric viruses, inorganic and organic particles, respectively. The influence of the inorganic (Kaolinite) or organic (Microcystis aeruginosa) particles on the survival of MS2 at different conditions, such as particles concentration, pH, ion concentration and natural organic matter (NOM) were studied. The results showed that Kaolinite had no effect on the survival of phage MS2 except that apparent survival of MS2 increased 1 logarithm in higher hardness water. Microcystis aeruginosa addition reduced 1 logarithm of MS2 survival. However, when the pH value was greater than 4.0 or the concentration of Microcystis aeruginosa was less than 1.0 x 10(6) cells x L(-1), Microcystis aeruginosa addition had no influence on the survival of MS2. In higher hardness water, Microcystis aeruginosa protected MS2 viruses and then increased the survival of MS2. In drinking water, resource containing higher concentration of particles, the survival ability of virus would be enhanced with the increase of the hardness and then elevated the risks of drinking water safety.

Virus adsorption of water-stable quaternized chitosan nanofibers

The burden of unsafe drinking water is responsible for millions of deaths each year. To relieve this burden, we are in search of an inexpensive material that can adsorb pathogens from drinking water. In this pursuit, we have studied the natural carbohydrate, chitosan. To impart virus removal features, chitosan has been functionalized with a quaternary amine to form quaternized chitosan N-[(2-hydroxyl-3-trimethylammonium) propyl] chitosan (HTCC). HTCC can be electrospun into nanofibers with the non-ionogenic polyvinyl alcohol (PVA), creating a high surface area mat. High surface area is a major requirement for effective adsorption processes. HTCC is antiviral and antimicrobial, making it a good material for water purification. However, HTCC dissolves in water. We have explored the parameters to crosslink the nanofibers with glutaraldehyde. We have imparted water stability so there is a maximum of 30% swelling of the fibers after 6h in water. The water stable fibers retain their ability to adsorb virus, as shown for an enveloped and nonenveloped virus. HTCC now has the potential to be incorporated into a microfiltration membrane that can remove viruses. This could create an inexpensive, low pressure filtration membrane for drinking water purification.

Inactivation of F-specific bacteriophages during flocculation with polyaluminum chloride - a mechanistic study

Bacteriophages are often used as surrogates for enteric viruses in spiking experiments to determine the efficiencies of virus removal of certain water treatment measures, like e.g. flocculation or filtration steps. Such spiking experiments with bacteriophages are indispensable if the natural virus concentrations in the raw water of water treatment plants are too low to allow the determination of elimination levels over several orders of magnitude. In order to obtain reliable results from such spiking tests, it is essential that bacteriophages behave comparable to viruses and remain stable during the experiments. To test this, the influence of flocculation parameters on the bacteriophages MS2, Qβ and phiX174 was examined. Notably, the F-specific phages MS2 and Qβ were found to be inactivated in flocculation processes with polyaluminum chloride (PACl). In contrast, other aluminum coagulants like AlCl3 or Al2(SO4)3 did not show a comparable effect on MS2 in this study. In experiments testing the influence of different PACl species on MS2 and Qβ inactivation during flocculation, it could be shown that cationic dissolved PACl species (Al13) interacted with the MS2 surface and hereby reduced the surviving phage fraction to c/c0 values below 1*10(-4) even at very low PACl concentrations of 7 μmol Al/L. Other inactivation mechanisms like the irreversible adsorption of phages to the floc structure or the damage of phage surfaces due to entrapment into the floc during coagulation and floc formation do not seem to contribute to the low surviving fraction found for both F-specific bacteriophages. Furthermore, no influence of phage agglomeration or pH drops during the flocculation process on phage inactivation could be observed. The somatic coliphage phiX174 in contrast did not show sensitivity to chemical stress and in accordance only slight interaction between Al13 and the phage surface was observed. Consequently, F-specific phages like MS2 should not be used as surrogate for viruses in flocculation experiments with PACl to determine the removal rates of viruses, as the results are influenced by a strong inactivation of the bacteriophages due to the experimental conditions.

Integrating quantitative PCR and Bayesian statistics in quantifying human adenoviruses in small volumes of source water

Rapid quantification of viral pathogens in drinking and recreational water can help reduce waterborne disease risks. For this purpose, samples in small volume (e.g. 1L) are favored because of the convenience of collection, transportation and processing. However, the results of viral analysis are often subject to uncertainty. To overcome this limitation, we propose an approach that integrates Bayesian statistics, efficient concentration methods, and quantitative PCR (qPCR) to quantify viral pathogens in water. Using this approach, we quantified human adenoviruses (HAdVs) in eighteen samples of source water collected from six drinking water treatment plants. HAdVs were found in seven samples. In the other eleven samples, HAdVs were not detected by qPCR, but might have existed based on Bayesian inference. Our integrated approach that quantifies uncertainty provides a better understanding than conventional assessments of potential risks to public health, particularly in cases when pathogens may present a threat but cannot be detected by traditional methods.

Norovirus contamination of a drinking water supply at a hotel resort

AIM

To investigate a waterborne gastroenteritis outbreak and consider wider environmental contamination concerns.

METHODS

An acute gastroenteritis outbreak was investigated through interviews, analysis of faecal samples, drinking water and environmental water samples.

RESULTS

A total of 53 cases reported an illness of acute gastroenteritis following stays and/or dining at a hotel or neighbouring resort in southern New Zealand over a 1-month period in early spring 2012. The consumption of table or tap water was strongly associated with the illness. Faecal samples were positive for norovirus (NoV) genogroup I and II (GI and GII). Drinking tap water samples were positive for NoV GI and GII but negative for Escherichia coli (E. coli). Wider environmental water testing at local drinking water sources, around the sewage disposal field and at the nearby river showed the presence of NoV GI and GII. Voluntary boil water notices were issued and implemented with no further cases following this action. Additional treatment of drinking water supplies has been implemented and sewerage disposal concerns referred to local government.

CONCLUSION

Investigation of this gastroenteritis outbreak revealed contamination of both drinking water and the wider environment with NoV. Bacterial indicators do not adequately cover contamination by viruses but due to costs, frequent virus monitoring programmes are currently impractical. A strategy to decrease environmental contamination of drinking water supplies in this busy tourist location through improved management of sewage disposal and drinking water is urgently required.

Nationwide surveillance for pathogenic microorganisms in groundwater near carcass burials constructed in South Korea in 2010

Widespread outbreaks of foot-and-mouth disease and avian influenza occurred in South Korea during 2010. In response to the culling of many animals to attenuate the spread of disease, South Korea used mass burial sites to dispose of the large number of carcasses; consequently, concerns about groundwater contamination by leachate from these burial sites are increasing. Groundwater is one of the main sources of drinking water, and its cleanliness is directly related to public health. Thus, this study aimed to evaluate the safety of groundwater around the burial sites (total of 600 sites). A total of 1,200 groundwater samples were collected though the country, and microbial analysis was conducted during two time periods: during the spring (n = 600; April to June 2012) and after rainfall (n = 600; August to October, 2012; fall). Fecal coliform and Escherichia coli were detected in 173 (14.4%) and 85 (7.1%) of the 1,200 samples, respectively. Salmonella spp. and Shigella spp. each were detected only once (0.083%). Clostridium perfringens was detected from 7 groundwater samples (0.583%), and E. coli O157:H7 was not detected. With respect to norovirus, only the GII type was detected from six groundwater samples (0.5%), and enterovirus was detected in 15 groundwater samples (1.25%). The frequency of E. coli that we detected was lower than that found in previous studies conducted in South Korea, but we detected higher frequency of fecal coliform than that observed in a previous report. The contamination frequencies of Salmonella spp. and Shigella spp. were very low, but C. perfringens, which could be an indicator of fecal pollution, was detected in seven regions. Overall, the results of the present study indicate a low possibility of contamination from burial sites. However, consistent monitoring is required to prevent microbial contamination of groundwater near the burial sites.

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.

[Drinking water regulations in Ukraine and infectious morbidity rate with water pathway of transmission of causative agents]

These are presented drinking water regulations in Ukraine on microbiological indices in the new state document "Hygienic Drinking water regulations intended for human consumption" (State sanitary regulations and standards (GsanPiN) 2.2.4-171-10). There is reported an analysis of both the open waterbodies water quality and water for centralized water supply in 2007-2011 and 1992-1996 also on sanitary-bacteriological indices for performance of comparative retrospective analysis. There has been shown water quality degradation for open waterbodies, the main sources of water supply for population. Against this background, a marked improvement of drinking water quality has been noted, the number of non-standard samples decreased to 3.6 % compared with 8.8% in the preceding 15 years. This index correlates with a decrease in the number of outbreaks of infections transmitted by water. There was noted unsatisfactory registration of viral infections with water pathway of transmission and the increase in morbidity rate of gastroenterocolitides of unknown etiology that may include acute viral intestinal infections. Expediency to keep "fermentation of glucose" test in bacteriological examination of water in the identification scheme of general coliforms has been substantiated.

Assessment of a portable handheld UV light device for the disinfection of viruses and bacteria in water

Effective individual microbiological water purifiers are needed for consumption of untreated water sources by campers, emergency use, military, and in developing counties. A handheld UV light device was tested to assess if it could meet the virus reduction requirements established by the United State Environmental Protection Agency, National Science Foundation and the World Health Organization. The device was found capable of inactivating at least 4 log₁₀ of poliovirus type 1, rotavirus SA-11 and MS-2 virus in 500 mL volumes of general case test water. But in the presence of high turbidity and organic matter, filtration was necessary to achieve a 4 log₁₀ reduction of the test viruses.

Presence of Torque teno virus (TTV) in tap water in public schools from Southern Brazil

Torque teno virus (TTV) was surveyed in tap water collected in schools from three municipalities located in the south of Brazil. TTV genomes were found in 11.7 % (4/34) of the samples. TTV DNA was detected in 10.5 % (2/19) of the samples collected at the city of Caxias do Sul and in 25 % (2/8) of the samples from Pelotas. Those cities have a low rate of sewage treatment. All samples from Santa Cruz do Sul, which has nearly 92 % of its sewage treated, were negative. These results suggest that the amount of sewage treated may have an effect on the detection rates of TTV DNA in drinking water in a given urban area, showing a mild negative correlation (r = -0.76), when comparing the percentage of sewage treatment to the detection of TTV genomes. The detection rate of TTV was also compared with Escherichia coli, showing a strong correlation (r = 0.97), indicating that TTV may be a suitable marker of fecal contamination.

[Spring water quality assessment regarding the problem of endemic fluorosis]

A possible variant for reducing the consumption of fluoride by population of Tver region is the use of water with low fluoride content, such as spring water. Assessment of drinking suitability of spring water (the content of physiologically important mineral elements and microbial purity) is relevant to our region. Water samples from 6 spring-water source of Tver region were studied during the year. The content of fluoride and calcium were measured by using an ion-selective electrodes. Microbiological purity tested by the presence of total coliform bacteria, thermotolerant coliform bacteria, coliphages and total microbial numbers. The analysis of some mineral components in spring water of Tver region showed that calcium content was in range 33-88 mg/l, that satisfied the recommended value; fluoride concentration is less then 0.5 mg/l. In all spring water samples total coliforms, thermotolerant coliforms and coliphages were absent. The total microbial number was in standard range, except of two spring-water source in the autumn and summer. The data suppose that spring water of Tver region can be used as a component of diet normalizing the fluoride consumption at risk of dental fluorosis in children.

Research considerations for more effective groundwater monitoring

Since numerous pathogens occur in feces, water is monitored for fecal contamination using indicator organisms rather than individual pathogens. Although this approach is supported by health effects data in recreational waters, it is questionable when used for drinking water. Most outbreaks in groundwater occur in systems that have not violated the US EPA's maximum contaminant limit (MCL) for total coliforms within 12 months before the outbreak. Additionally, environmentally stable viruses and parasites are often detected in drinking water samples with no detectable indicators. Recent detections of Escherichia coli O157:H7 and Campylobacter jejuni in groundwaters in the apparent absence of indicators also cast some doubt on the worth of indicators for fecal bacterial pathogens. Individual pathogen monitoring is now technically achievable but currently unreasonable due to the number of possible pathogens and the costs involved. Several alternatives to pathogen monitoring could significantly reduce the frequency at which pathogens occur in waters testing negative for indicators: (i) increasing sample volumes for indicators, (ii) increasing monitoring frequency, (iii) using a suite of indicators, (iv) using a more conservative polymerase chain reaction (PCR) method, (v) sampling when fecal contamination is most likely present or (vi) any combination of these options.

Epidemiological and molecular analysis of a waterborne outbreak of norovirus GII.4

Contaminated water is one of the main sources of norovirus (NoV) gastroenteritis outbreaks globally. Waterborne NoV outbreaks are infrequently attributed to GII.4 NoV. In September 2009, a NoV outbreak affected a small school in Guangdong Province, China. Epidemiological investigations indicated that household use water, supplied by a well, was the probable source (relative risk 1·9). NoV nucleic acid material in concentrated well-water samples was detected using real-time RT-PCR. Nucleotide sequences of NoV extracted from diarrhoea and well-water specimens were identical and had the greatest sequence identity to corresponding sequences from the epidemic strain GII.4-2006b. Our report documents the first laboratory-confirmed waterborne outbreak caused by GII.4 NoV genotype in China. Our investigations indicate that well water, intended exclusively for household use but not for consumption, caused this outbreak. The results of this report serve as a reminder that private well water intended for household use should be tested for NoV.

[A viral meningitis outbreak associated with Echo30 in drinking water]

OBJECTIVE

To study the source of infection, the scope of epidemic and control measures in an outbreak involving students having symptoms as fever, dizziness, headache, vomiting and nausea.

METHODS

The suspected-case was defined as fever (armpit temperature ≥ 37°C) and with one or more of the following symptoms: dizziness, headache, vomiting and nausea, among students and teachers at school from Mar 1, 2012. Confirmed-case was among suspected case accompanied by both throat and rectal swabs enterovirus positive by RT-PCR. All the cases were collected through checking the medical records from 4 hospitals as well as through the absence records of students and teachers, from Mar 1, 2012. We conducted a case-control study with ratio of 1:2 and data on the exposures to water among students and teachers was collected prior to the illness. 27 cases' throat and rectal swabs were collected and analyzed by RT-PCR and PCR sequence methods. 2 warm-water samples were collected for testing the counts on total bacteria and E. coli.

RESULTS

103 students' cases were identified in school L, with the attack rate as 4.6% (103/2255). Students from Grade three had the high attack rate as 18.1% (72/397) and 77.7% (80/103) of the cases located in the building with 'multiple-functions'. Epidemic curve of the outbreak showed a pattern with continuous common source of infection. It seemed that the exposure to warm-water appeared to be the major risk factor (OR = 18.3, 95%CI: 2.0 - 169.5) together with the intake of un-boiled water (OR = 15.5, 95%CI: 1.7 - 141.8). Specimens from 27 students (81.5%, 22/27) were identified enterovirus positive by RT-PCR, and 7 of the 9 students were confirmed carrying Echo 30. Bacteria and coli were negative from the 2 warm-water samples.

CONCLUSION

This viral meningitis-outbreak was caused by Echo 30, with drinking water as the major risk factor.

Risk of viral acute gastrointestinal illness from nondisinfected drinking water distribution systems

Acute gastrointestinal illness (AGI) resulting from pathogens directly entering the piping of drinking water distribution systems is insufficiently understood. Here, we estimate AGI incidence from virus intrusions into the distribution systems of 14 nondisinfecting, groundwater-source, community water systems. Water samples for virus quantification were collected monthly at wells and households during four 12-week periods in 2006-2007. Ultraviolet (UV) disinfection was installed on the communities' wellheads during one study year; UV was absent the other year. UV was intended to eliminate virus contributions from the wells and without residual disinfectant present in these systems, any increase in virus concentration downstream at household taps represented virus contributions from the distribution system (Approach 1). During no-UV periods, distribution system viruses were estimated by the difference between well water and household tap virus concentrations (Approach 2). For both approaches, a Monte Carlo risk assessment framework was used to estimate AGI risk from distribution systems using study-specific exposure-response relationships. Depending on the exposure-response relationship selected, AGI risk from the distribution systems was 0.0180-0.0661 and 0.001-0.1047 episodes/person-year estimated by Approaches 1 and 2, respectively. These values represented 0.1-4.9% of AGI risk from all exposure routes, and 1.6-67.8% of risk related to drinking water exposure. Virus intrusions into nondisinfected drinking water distribution systems can contribute to sporadic AGI.

Measuring and mitigating inhibition during quantitative real time PCR analysis of viral nucleic acid extracts from large-volume environmental water samples

Naturally-occurring inhibitory compounds are a major concern during qPCR and RT-qPCR analysis of environmental samples, particularly large volume water samples. Here, a standardized method for measuring and mitigating sample inhibition in environmental water concentrates is described. Specifically, the method 1) employs a commercially available standard RNA control; 2) defines inhibition by the change in the quantification cycle (C(q)) of the standard RNA control when added to the sample concentrate; and 3) calculates a dilution factor using a mathematical formula applied to the change in C(q) to indicate the specific volume of nuclease-free water necessary to dilute the effect of inhibitors. The standardized inhibition method was applied to 3,193 large-volume water (surface, groundwater, drinking water, agricultural runoff, sewage) concentrates of which 1,074 (34%) were inhibited. Inhibition level was not related to sample volume. Samples collected from the same locations over a one to two year period had widely variable inhibition levels. The proportion of samples that could have been reported as false negatives if inhibition had not been mitigated was between 0.3% and 71%, depending on water source. These findings emphasize the importance of measuring and mitigating inhibition when reporting qPCR results for viral pathogens in environmental waters to minimize the likelihood of reporting false negatives and under-quantifying virus concentration.

Viruses in nondisinfected drinking water from municipal wells and community incidence of acute gastrointestinal illness

BACKGROUND

Groundwater supplies for drinking water are frequently contaminated with low levels of human enteric virus genomes, yet evidence for waterborne disease transmission is lacking.

OBJECTIVES

We related quantitative polymerase chain reaction (qPCR)-measured enteric viruses in the tap water of 14 Wisconsin communities supplied by nondisinfected groundwater to acute gastrointestinal illness (AGI) incidence.

METHODS

AGI incidence was estimated from health diaries completed weekly by households within each study community during four 12-week periods. Water samples were collected monthly from five to eight households per community. Viruses were measured by qPCR, and infectivity assessed by cell culture. AGI incidence was related to virus measures using Poisson regression with random effects.

RESULTS

Communities and time periods with the highest virus measures had correspondingly high AGI incidence. This association was particularly strong for norovirus genogroup I (NoV-GI) and between adult AGI and enteroviruses when echovirus serotypes predominated. At mean concentrations of 1 and 0.8 genomic copies/L of NoV-GI and enteroviruses, respectively, the AGI incidence rate ratios (i.e., relative risk) increased by 30%. Adenoviruses were common, but tap-water concentrations were low and not positively associated with AGI. The estimated fraction of AGI attributable to tap-water-borne viruses was between 6% and 22%, depending on the virus exposure-AGI incidence model selected, and could have been as high as 63% among children < 5 years of age during the period when NoV-GI was abundant in drinking water.

CONCLUSIONS

The majority of groundwater-source public water systems in the United States produce water without disinfection, and our findings suggest that populations served by such systems may be exposed to waterborne viruses and consequent health risks.

Occurrence of viruses and protozoa in drinking water sources of Japan and their relationship to indicator microorganisms

A nationwide survey of viruses, protozoa, and indicator microorganisms in drinking water sources of Japan was conducted. Among 64 surface water samples collected from 16 drinking water treatment plants, 51 (80 %) samples were positive for at least one of the 11 pathogen types tested, including noroviruses of genogroups I (positive rate, 13 %) and II (2 %), human sapoviruses (5 %), human adenoviruses of serotypes 40 and 41 (39 %), Cryptosporidium oocysts (41 %), and Giardia cysts (36 %). Total coliforms, Escherichia coli, and F-specific coliphages were detected in 63 (98 %), 33 (52 %), and 17 (27 %) samples, respectively, and E. coli was judged to be the most suitable indicator of pathogen contamination of drinking water sources. Genogroup-specific real-time PCR for F-specific coliphages revealed the presence of F-specific RNA coliphages of animal genogroup I and human genogroups II and III in 13 (41 %), 12 (39 %), and 1 (3 %), respectively, of 31 plaques isolated.