Epoxy-Fiberglass Adsorbent for Concentrating Viruses from Large Volumes of Potable Water

A simple and compact virus-adsorbing unit for efficiently concentrating human enteric viruses from 100 gallons (about 380 liters) or more of potable water is described.     

Clostridium perfringens and somatic coliphages as indicators of the efficiency of drinking water treatment for viruses and protozoan cysts.

To find the most suitable indicator of viral and parasitic contamination of drinking water, large-volume samples were collected and analyzed for the presence of pathogens (cultivable human enteric viruses, Giardia lamblia cysts, and Cryptosporidium oocysts) and potential indicators (somatic and male-specific coliphages, Clostridium perfringens). The samples were obtained from three water treatment plants by using conventional or better treatments (ozonation, biological filtration). All samples of river water contained the microorganisms sought, and only C. perfringens counts were correlated with human enteric viruses, cysts, or oocysts. For settled and filtered water samples, all indicators were statistically correlated with human enteric viruses but not with cysts or oocysts. By using multiple regression, the somatic coliphage counts were the only explanatory variable for the human enteric virus counts in settled water, while in filtered water samples it was C. perfringens counts. Finished water samples of 1,000 liters each were free of all microorganisms, except for a single sample that contained low levels of cysts and oocysts of undetermined viability. Three of nine finished water samples of 20,000 liters each revealed residual levels of somatic coliphages at 0.03, 0.10, and 0.26 per 100 liters. Measured virus removal was more than 4 to 5 log10, and cyst removal was more than 4 log10. Coliphage and C. perfringens counts suggested that the total removal and inactivation was more than 7 log10 viable microorganisms. C. perfringens counts appear to be the most suitable indicator for the inactivation and removal of viruses in drinking water treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fate of human enteric viruses, coliphages, and Clostridium perfringens during drinking-water treatment.

The elimination of human enteric viruses, coliphages, and Clostridium perfringens was studied during a conventional complete drinking-water treatment process. The respective concentrations (geometric mean) of these microorganisms in 100-L samples of river water were, respectively, as follows: viruses, 79 mpniu (most probable number of infectious units) per 100 L, coliphages, 6565 pfu (plaque-forming units) per 100 L. and clostridia, 11,349 cfu (colony-forming units) per 100 L. After predisinfection, flocculation with alum, and settling, human enteric viruses were not detected in any of the 100-L samples (less than 4 mpniu/100 L), but coliphages were detected in 7 of 14 samples and clostridia in 15 of 16 samples. In filtered water samples, human enteric viruses were detected in 2 of 31 samples, coliphages in 10 of 33, and clostridia in 17 of 33. Finished water was free of human enteric viruses (0/162 samples), but coliphages were detected in one sample (1.5 pfu/100 L) and clostridia in three, at 1.0, 4.1, and 7.0 cfu/100 L. It thus appears that coliphages and clostridia, which are present in larger numbers than viruses in river water and which may have similar resistance to drinking-water treatments, may be useful for estimating the level of treatment attained when large volumes of water (1000 L or greater) are sampled.     

Effects of bentonite clay solids on poliovirus concentration from water by microporous filter methods.

To determine whether suspended solids interfere with enteric virus recovery from water by microporous filter methods, the effects of bentonite clay solids at a concentration of 10 nephelometric turbidity units on the recovery of poliovirus type 1 from seeded, activated carbon-treated, filtered tap water were studied. Volumes (500 ml) of virus-laden water at pH 5.5 or 7.5, with and without 50 mM MgCl2, were filtered through 47-mm-diameter, electropositive (Virosorb 1MDS) and electronegative (Filterite) filters that had been pretreated with Tween 80 to minimize direct virus adsorption to filter surfaces. Bentonite solids enhanced virus retention on both types of filters, even under conditions in which viruses were not solids associated. However, bentonite solids also interfered with elution of retained viruses when eluting with 0.3% beef extract-50 mM glycine (pH 9.5). Under some conditions, overall virus recoveries were lower from water with bentonite solids than from solids-free control water. The results of this study indicate that clay turbidity can interfere somewhat with virus recovery by current microporous filter methods.     

Effects of bentonite clay solids on poliovirus concentration from water by microporous filter methods

To determine whether suspended solids interfere with enteric virus recovery from water by microporous filter methods, the effects of bentonite clay solids at a concentration of 10 nephelometric turbidity units on the recovery of poliovirus type 1 from seeded, activated carbon-treated, filtered tap water were studied. Volumes (500 ml) of virus-laden water at pH 5.5 or 7.5, with and without 50 mM MgCl2, were filtered through 47-mm-diameter, electropositive (Virosorb 1MDS) and electronegative (Filterite) filters that had been pretreated with Tween 80 to minimize direct virus adsorption to filter surfaces. Bentonite solids enhanced virus retention on both types of filters, even under conditions in which viruses were not solids associated. However, bentonite solids also interfered with elution of retained viruses when eluting with 0.3% beef extract-50 mM glycine (pH 9.5). Under some conditions, overall virus recoveries were lower from water with bentonite solids than from solids-free control water. The results of this study indicate that clay turbidity can interfere somewhat with virus recovery by current microporous filter methods.     

Wound fiberglass depth filters as a less expensive approach for the concentration of viruses from water

Wound fiberglass depth cartridge filters (25.4 cm) with a nominal porosity of 1 micron were used to concentrate viruses from large volumes of surface water. They were found to be an excellent, less expensive alternative to the 0.2-micron pleated cartridge filters normally used for the concentration of enteric viruses from water. More than 99% of experimentally seeded poliovirus was adsorbed to these filters when the pH of the water was adjusted to pH 3.5 and aluminium chloride was added to a final concentration of 0.001 M, as recommended for electronegative filters. In comparative recovery of indigenous viruses from river water, similar results were obtained with two 1-micron or a 3-microns + 0.2-micron filter combination. The cost of the two 1-micron filters is about Can. $26, while it is about Can. $58 for the other combination.     

Detection of enteric viruses in treated drinking water.

The occurrence of viruses in conventionally treated drinking water derived from a heavily polluted source was evaluated by collecting and analyzing 38 large-volume (65- to 756-liter) samples of water from a 9 m3/s (205 X 10(6) gallons [776 X 10(6) liters] per day) water treatment plant. Samples of raw, clarified, filtered, and chlorinated finished water were concentrated by using the filter adsorption-elution technique. Of 23 samples of finished water, 19 (83%) contained viruses. None of the nine finished water samples collected during the dry season contained detectable total coliform bacteria. Seven of nine finished water samples collected during the dry season met turbidity, total coliform bacteria, and total residual chlorine standards. Of these, four contained virus. During the dry season the percent removals were 25 to 93% for enteric viruses, 89 to 100% for bacteria, and 81% for turbidity. During the rainy season the percent removals were 0 to 43% for enteric viruses, 80 to 96% for bacteria, and 63% for turbidity. None of the 14 finished water samples collected during the rainy season met turbidity standards, and all contained rotaviruses or enteroviruses.     

Enteric virus survival during household laundering and impact of disinfection with sodium hypochlorite

This study was conducted to determine whether enteric viruses (adenovirus, rotavirus, and hepatitis A virus) added to cotton cloth swatches survive the wash cycle, the rinse cycle, and a 28-min permanent press drying cycle as commonly practiced in households in the United States. Detergent with and without bleach (sodium hypochlorite) was added to washing machines containing sterile and virus-inoculated 58-cm2 swatches, 3.2 kg of cotton T-shirts and underwear, and a soiled pillowcase designed to simulate the conditions (pH, organic load, etc.) encountered in soiled laundry. The most important factors for the reduction of virus in laundry were passage through the drying cycle and the addition of sodium hypochlorite. Washing with detergent alone was not found to be effective for the removal or inactivation of enteric viruses, as significant concentrations of virus were found on the swatches (reductions of 92 to 99%). It was also demonstrated that viruses are readily transferred from contaminated cloths to uncontaminated clothes. The use of sodium hypochlorite reduced the number of infectious viruses on the swatches after washing and drying by at least 99.99%. Laundering practices in common use in the United States do not eliminate enteric and respiratory viruses from clothes. The use of bleach can further reduce the numbers of enteric viruses in laundry.     

Detection of enteric viruses in treated drinking water

The occurrence of viruses in conventionally treated drinking water derived from a heavily polluted source was evaluated by collecting and analyzing 38 large-volume (65- to 756-liter) samples of water from a 9 m3/s (205 X 10(6) gallons [776 X 10(6) liters] per day) water treatment plant. Samples of raw, clarified, filtered, and chlorinated finished water were concentrated by using the filter adsorption-elution technique. Of 23 samples of finished water, 19 (83%) contained viruses. None of the nine finished water samples collected during the dry season contained detectable total coliform bacteria. Seven of nine finished water samples collected during the dry season met turbidity, total coliform bacteria, and total residual chlorine standards. Of these, four contained virus. During the dry season the percent removals were 25 to 93% for enteric viruses, 89 to 100% for bacteria, and 81% for turbidity. During the rainy season the percent removals were 0 to 43% for enteric viruses, 80 to 96% for bacteria, and 63% for turbidity. None of the 14 finished water samples collected during the rainy season met turbidity standards, and all contained rotaviruses or enteroviruses.     

Molecular detection of human enteric viruses in urban rivers in Korea

We performed RT-nested PCR to study the distribution of human enteric viruses in urban rivers in Korea. During 2002-2003, water samples were collected from four rivers in Gyeonggi Province, South Korea. Among 58 samples, 45 (77.6%), 32 (55.2%), 12 (20.7%), 2 (3.4%), 4 (6.9%), and 4 (6.9%) showed positive results with adenoviruses (AdVs), enteroviruses (EVs), reoviruses (ReVs), hepatitis A viruses (HAVs), rotaviruses (RoVs), and sapoviruses (SVs), respectively. According to the binary logistic regression model, the occurrence of each enteric virus, except ReVs and HAVs, was not statistically correlated with the water temperature and levels of fecal coliforms (P<0.05). AdVs were most often detected; only 4 samples (6.9%) were negative for AdVs while positive for other enteric viruses in the studied sites. Our results indicated that monitoring human enteric viruses is necessary to improve microbial quality, and that AdVs detection by PCR can be a useful index for the presence of other enteric viruses in aquatic environments.     

Development of Methods for Detecting Viruses in Solid Waste Landfill Leachates

Methods were developed for detecting and concentrating enteric viruses in municipal solid waste landfill leachates. Poliovirus added to a leachate was not readily detectable, possibly because the virus was adsorbed to the leachate particulates. The masking effects associated with suspended solids in the leachate were overcome by adding a final 0.1 M sodium (tetra)ethylenediaminetetraacetate concentration to the leachate. A sodium (tetra)ethylenediaminetetraacetate-treated leachate could be clarified by filtration at pH 8.0 without a loss of virus. The clarified and sodium (tetra)ethylenediaminetetraacetate-treated leachate contained interfering materials of an anionic nature which prevented virus adsorption to epoxy-fiber glass filters. This interfering effect was overcome by treating the leachate with an anion-exchange resin. Viruses in the resin-treated leachate were concentrated by adjusting the leachate to pH 3.5, adding AlCl(3) to a final 0.005 M concentration, adsorbing the viruses to an epoxy-fiber glass virus adsorbent, and eluting the adsorbed viruses in a small volume. When this method was used to concentrate poliovirus 100-fold in a variety of leachates, the average virus recovery efficiency was 37%. With the methods described in this study, it should be possible to efficiently monitor solid waste disposal site leachates for enteric viruses.     

Enteric Virus Survival during Household Laundering and Impact of Disinfection with Sodium Hypochlorite

This study was conducted to determine whether enteric viruses (adenovirus, rotavirus, and hepatitis A virus) added to cotton cloth swatches survive the wash cycle, the rinse cycle, and a 28-min permanent press drying cycle as commonly practiced in households in the United States. Detergent with and without bleach (sodium hypochlorite) was added to washing machines containing sterile and virus-inoculated 58-cm² swatches, 3.2 kg of cotton T-shirts and underwear, and a soiled pillowcase designed to simulate the conditions (pH, organic load, etc.) encountered in soiled laundry. The most important factors for the reduction of virus in laundry were passage through the drying cycle and the addition of sodium hypochlorite. Washing with detergent alone was not found to be effective for the removal or inactivation of enteric viruses, as significant concentrations of virus were found on the swatches (reductions of 92 to 99%). It was also demonstrated that viruses are readily transferred from contaminated cloths to uncontaminated clothes. The use of sodium hypochlorite reduced the number of infectious viruses on the swatches after washing and drying by at least 99.99%. Laundering practices in common use in the United States do not eliminate enteric and respiratory viruses from clothes. The use of bleach can further reduce the numbers of enteric viruses in laundry.     

Microbiological and virological analysis of water from two water filtration plants and their distribution systems

The microbial flora of the water produced by two water filtration plants and their drinking water distribution system were evaluated: the Pont-Viau (PV) and the Repentigny (RE) water filtration plants. Untreated water entering the plants contained 3.6 (PV) and 16.8 most probable number of infectious units (mpniu)/L (RE) enteric viruses and total coliform bacteria counts were 300,000 (PV) and 500,000 cfu/L (RE). Treated water leaving the plant was essentially free of all the bacterial indicators measured (total, stressed, and fecal coliforms; Aeromonas hydrophila; Pseudomonas aeruginosa; Clostridium perfringens; enterococci) as well as of human enteric viruses. Heterotrophic plate counts at 20 and 35 degrees C were low in the freshly treated water leaving the plants, but bacterial regrowth was observed in both distribution systems at all sampling sites. Average counts for the heterotrophic plate count (20 degrees C) were between 10(6) and 10(7) cfu/L and counts were clearly increased with the distance from the plant. The most numerous bacterial genera encountered were Bacillus, Flavobacterium, and Pseudomonas (nonaeruginosa).     

Effect of kaolinite on the specific infectivity of reovirus

Abstract The infectivity of enteric viruses (e.g., poliovirus, rotavirus, reovirus) is prolonged when these viruses are adsorbed on naturally occurring particulates (sediments, clay minerals) in terrestrial and aquatic environments. Furthermore, in vitro assays of these and other particulate-associated viruses often display infectivity levels (specific infectivity) greater than those of the same concentration of viruses in the absence of particulates. This investigations attempted to identify interactions at the particulate-virus-cell interface and to define the mechanism(s) whereby the apparent infectivity of viruses is enhanced when complexed with particulates. Reovirus type 3 and the clay mineral, kaolinite, were used as the model systems. Scanning electron micrographs after critical point drying showed that kaolinite was not present on the surface of cell monolayers of L-929 mouse fibroblasts 3 h after inoculation with a kaolinite-reovirus complex. However, the virus was observed on the surface of the cells. No change in dispersion of the virus particles was observed nor was the integrity of the cell surface altered by kaolinite. These results indicated that kaolinite enhanced the transport of viral particles, in conjunction with diffusion and Brownian movement, to receptors for the reovirus on the cell surface.     

Method for detecting viruses in aerosols

A simple method with poliovirus as the model was developed for recovering human enteric viruses from aerosols. Filterite filters (pore size, 0.45 micron; Filterite Corp., Timonium, Md.) moistened with glycine buffer (pH 3.5) were used for adsorbing the aerosolized virus. No virus passed the filter, even with air flow rates of 100 liters/min. Virus recovery from the filter was achieved by rapid elution with 800 ml of glycine buffer, pH 10. The virus in the primary eluate was reconcentrated by adjusting the pH to 3.5, adding AlCl3 to 0.0005 M, collecting the virus on a 0.25-micron-pore Filerite disk (diameter, 25 mm) and and eluting with 6 ml of buffer, pH 10. With this method, virus could be detected regularly in aerosols produced by flushing when 3 X 10(8) PFU of poliovirus were present in the toilet bowl. Poliovirus-containing fecal material from two of four infants who had recently received oral polio vaccine also yielded virus in the aerosols when feces containing 2.4 X 10(7) to 4.5 X 10(7) PFU of virus had been added to the toilet bowl. Persons infected with a variety of natural enteric viruses are known to excrete this amount of virus in their daily stools.     

Method for detecting viruses in aerosols.

A simple method with poliovirus as the model was developed for recovering human enteric viruses from aerosols. Filterite filters (pore size, 0.45 micron; Filterite Corp., Timonium, Md.) moistened with glycine buffer (pH 3.5) were used for adsorbing the aerosolized virus. No virus passed the filter, even with air flow rates of 100 liters/min. Virus recovery from the filter was achieved by rapid elution with 800 ml of glycine buffer, pH 10. The virus in the primary eluate was reconcentrated by adjusting the pH to 3.5, adding AlCl3 to 0.0005 M, collecting the virus on a 0.25-micron-pore Filerite disk (diameter, 25 mm) and and eluting with 6 ml of buffer, pH 10. With this method, virus could be detected regularly in aerosols produced by flushing when 3 X 10(8) PFU of poliovirus were present in the toilet bowl. Poliovirus-containing fecal material from two of four infants who had recently received oral polio vaccine also yielded virus in the aerosols when feces containing 2.4 X 10(7) to 4.5 X 10(7) PFU of virus had been added to the toilet bowl. Persons infected with a variety of natural enteric viruses are known to excrete this amount of virus in their daily stools.     

Hepatitis E virus‐based evaluation of a virion concentration method and detection of enteric viruses in environmental samples by multiplex nested RT‐PCR

Aims: The prevalence of enteric viruses in drinking and river water samples collected from Pune, India was assessed. During an outbreak of HEV in a small town near pune, water samples were screened for enteric viruses. Methods and Results: The water samples were subjected to adsorption–elution‐based virus concentration protocol followed by multiplex nested PCR. Among 64 Mutha river samples, 49 (76·56%) were positive for Hepatitis A Virus, 36 (56·25%) were positive for Rotavirus, 33 (51·56%) were positive for Enterovirus and 16 (25%) were positive for Hepatitis E Virus RNA. Only enterovirus RNA was detected in 2/662 (0·3%) drinking water samples, and the samples from the city’s water reservoir tested negative for all four viruses. HEV RNA was detected in three out of four river water samples during HEV outbreak and partial sequences from patients and water sample were identical. Conclusions: The study suggests absence of enteric viruses both in the source and in the purified water samples from Pune city, not allowing evaluation of the purification system and documents high prevalence of enteric viruses in river water, posing threat to the community. Significance and Impact of the Study: The rapid, sensitive and relatively inexpensive protocol developed for virological evaluation of water seems extremely useful and should be adapted for evaluating viral contamination of water for human consumption. This will lead to development of adequate control measures thereby reducing disease burden because of enteric viruses.     

环境介质中病毒生态的研究

病毒是许多人及重要经济动、植物病患的病原。一些病毒在环境中可因条件不同而生存数小时到数月, 并在水、气、士中迁移达若干公里。现有的污水处理方法对病毒, 特别是肠道病毒效果欠佳, 土地处置原污泥以及污水灌溉的水果和蔬菜能传播人肠道病毒。即使小至一个组织培养的感染剂量(病毒)也可引起人的疾病, 因此对环境介质中, 特别是饮水和食物中的少量病毒的去除也是重要的。现有的指示物不能确切地指示粪便污染, 更不能充分反映人肠道病毒的污染。大肠菌噬菌体在地表水、地下水和污水中比人肠道病毒更呈持久性, 还有许多适于选择分析技术特有性能, 因此很可能在一定条件下用它作人肠道病毒的指示物。作者对我国今后需要开展的研究提出了建议。     

Detection of animal and human enteric viruses in water from the Assomption River and its tributaries

Animal enteroviruses, reoviruses, and human enteric viruses were detected in water samples (20 L) from a major river system, the Assomption River in the province of Quebec. Animal enteroviruses, probably of porcine origin (this region is a major producer of pork), were isolated on porcine cell cultures and were found in 29 to 60% of water samples from the different sites on the river and in 19 to 48% of the water samples from the tributaries. The average concentration of these animal enteroviruses in water from the Assomption River was 2 to 7 mpniu/L (most probable number of infectious units per litre), and that from the tributaries varied from 3 to 24 mpniu/L. Reoviruses were detected in infected cell cultures by an enzyme-linked immunosorbent assay. Their origin is probably avian (broiler chicken farms) or human (untreated domestic waste waters) and they were detected in 19 to 52% of the water samples from the Assomption River at an average concentration of 3 to 12 mpniu/L. In water samples from the tributaries, 5 to 71% of the samples were positive at an average concentration of 5 to 24 mpniu/L. Human enteric viruses were detected in MA-104 cells by an immunoperoxidase assay using human immune serum globulin. They were detected in 13 to 72% of water samples from the Assomption River and 14 to 71% of the water samples from the tributaries. The average concentration of these human enteric viruses in Assomption River water varied from 1 to 12 and from 2 to 145 mpniu/L in water samples from the tributaries.(ABSTRACT TRUNCATED AT 250 WORDS)     

Detection and molecular characterization of enteric viruses in environmental samples in Monastir,Tunisia between January 2003 and April 2007

Aims: A prospective study was performed to characterize the main human enteric viruses able to persist in sewage samples and in shellfish tissues, and to establish the correlation between environmental strains and viral infantile diarrhoea observed in the same area during the same period. Methods and Results: A total of 250 sewage (raw and treated) and 60 shellfish samples were collected between January 2003 and April 2007 in Monastir region, Tunisia. Group A rotavirus (RVA) was detected in 80 (32%) sewage samples, norovirus (NoV) in 11 (4·4%) and enteric adenovirus (AdV) in 1 (0·4%). Among 60 shellfish samples collected near sewage effluents, one was contaminated by NoV (1·6%). Conclusion: Our data represent the first documentation in Tunisia, combining gastroenteritis viruses circulating in the environment and in clinical isolates. We observed a correlation between environmental strains and those found in children suffering from gastroenteritis during the same period study. This suggests the existence of a relationship between water contamination and paediatric diarrhoea. Significance and Impact of the Study: Our results address the potential health risks associated with transmission of human enteric viruses through water‐related environmental routes. The research findings will aid in elucidating the molecular epidemiology and circulation of enteric viruses in Tunisia and in Africa, where data are rare.