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1.
Lett Appl Microbiol ; 71(1): 117-123, 2020 Jul.
Article in English | MEDLINE | ID: mdl-31648373

ABSTRACT

Hog production takes place mostly in large concentrated animal feeding operations (CAFOs) where waste is managed by storing in lagoons prior to land application of lagoon liquid. Salmonella, including antibiotic-resistant Salmonella, have been found in the farm environment and lagoons. The objective of this research was to determine whether Salmonella resistant to clinically relevant antibiotics were present in wastewaters and surface waters from hog CAFOs. Samples of hog waste and on farm environmental waters were analysed for Salmonella, which were tested for antimicrobial susceptibility. The highest percentage of resistant isolates were found in raw waste flushed from hog houses and in lagoon wastewater; few resistant isolates were found in on-farm surface water. Resistance to sulphamethoxazole was most common, mostly in waste samples and less commonly in surface water, followed by chloramphenicol and ampicillin. No resistance to cephalosporin or fluoroquinolones was found. Resistance to clinically relevant antibiotics was commonly found in Salmonella from hog waste but was less extensive in farm surface waters. Management of wastes from hog CAFOs should be designed to further reduce the risk of human exposures resulting from environmental contamination with Salmonella. SIGNIFICANCE AND IMPACT OF THE STUDY: This study suggests antibiotic-resistant Salmonella were common in hog wastes and present in environmental waters associated with hog CAFOs. Low levels of antibiotic-resistant Salmonella in on-farm stream waters suggest surface waters could have been contaminated, potentially serving as a mechanism of off-farm transport. Since the study, there have been multiple economic, regulatory and practice changes at the federal, state and industry level. These include regulation of antibiotic use and animal waste treatment, vertical integration in the industry and changes in antibiotic use practice. This study is a useful historical baseline against which current antibiotic resistance trends can be measured.


Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial/genetics , Salmonella/genetics , Wastewater/microbiology , Ampicillin/pharmacology , Animal Feed/microbiology , Animals , Chloramphenicol/pharmacology , Farms , Humans , Rivers , Salmonella/drug effects , Salmonella/isolation & purification , Sulfamethoxazole/pharmacology , Swine/microbiology , Swine Diseases/microbiology
2.
J Appl Microbiol ; 126(3): 985-994, 2019 Mar.
Article in English | MEDLINE | ID: mdl-30592123

ABSTRACT

AIMS: The purpose of this study was to evaluate the effects of temperature, mixing and sunlight exposure on the 5-day survival of Escherichia coli, Enterococcus sp., F+/male-specific coliphages, somatic coliphages and Clostridium perfringens spores in an 80/20 blend of surface water and reclaimed water approved for potable reuse in North Carolina. METHODS AND RESULTS: Grab samples of tertiary treated, dual disinfected North Carolina 'Type 2' reclaimed water were collected and mixed with ambient surface waters to create the 80/20 mix and then spiked with naturally occurring organisms present in the blended water or organisms isolated from sewage. Organism survival over the 5-day period was evaluated at 4 and 20°C, 0, 60 and 120 rev min-1 mixing speeds and exposure to sunlight or darkness. The log10 survival ratio was then calculated for each organism at each condition. CONCLUSIONS: There were measurable differences between the log10 survival ratios at 5 days for most organisms; indicating that storage can decrease microbial concentrations. Mixing conditions were not a significant factor in microbe survival over the 5-day storage period. Sunlight was the most effective treatment factor to decrease log10 survival during 5-day storage. SIGNIFICANCE AND IMPACT OF THE STUDY: No previous studies have evaluated the survival of micro-organisms in the NC approved 80/20 blend of surface and reclaimed water over the 5-day storage. This study provides the first results on the survival of regulated faecal indicator organisms stored for 5 days in blended water under different environmental conditions.


Subject(s)
Bacteria/radiation effects , Disinfection , Fresh Water/microbiology , Water Microbiology , Bacterial Physiological Phenomena , Sunlight , Water Purification
3.
Water Res ; 79: 39-47, 2015 Aug 01.
Article in English | MEDLINE | ID: mdl-25965886

ABSTRACT

This study aimed to evaluate the relationship between FRNA coliphages (FRNA GI to GIV) and human enteric viruses (human adenoviruses, HAdV, astroviruses, AstV, noroviruses, NoV, and rotaviruses, RoV) in a tropical urban freshwater catchment. Positive associations between human-specific coliphages and human viral pathogens substantiate their use as viral indicators and in microbial source tracking. Reverse transcription qPCR was used to measure the concentrations of viruses and FRNA coliphages in concentrated water samples. Environmental water samples were also analyzed for male-specific (F+) and somatic (Som) coliphages using plaque assay. The most abundant enteric virus was NoV (55%) followed by HAdV (33%), RoV (33%), and AstV (23%), while the most abundant FRNA genogroup was GI (85%) followed by GII (48%), GIV (8%) and GIII (7%). Concentrations of human-specific coliphages FRNA GII were positively correlated with NoV, HAdV, RoV, AstV, F+ and Som (τ = 0.5 to 0.3, P < 0.05) while concentrations of animal-specific coliphages FRNA GI were negatively correlated with HAdV and RoV (τ = -0.2, P < 0.05). This study demonstrates statistical relationships between human-specific coliphages and a suite of human enteric viruses in the environment.


Subject(s)
Coliphages/isolation & purification , Fresh Water/virology , RNA Viruses/isolation & purification , Water Microbiology , Adenoviruses, Human/genetics , Adenoviruses, Human/isolation & purification , Astroviridae/genetics , Astroviridae/isolation & purification , Coliphages/genetics , Enterovirus/genetics , Enterovirus/isolation & purification , Environmental Monitoring , Norovirus/genetics , Norovirus/isolation & purification , RNA Viruses/genetics , Rotavirus/genetics , Rotavirus/isolation & purification , Singapore , Tropical Climate , Water Quality
4.
Appl Environ Microbiol ; 81(3): 850-60, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25416765

ABSTRACT

The suitability of traditional microbial indicators (i.e., Escherichia coli and enterococci) has been challenged due to the lack of correlation with pathogens and evidence of possible regrowth in the natural environment. In this study, the relationships between alternative microbial indicators of potential human fecal contamination (Bacteroides thetaiotaomicron, Methanobrevibacter smithii, human polyomaviruses [HPyVs], and F+ and somatic coliphages) and pathogens (Salmonella spp., Pseudomonas aeruginosa, rotavirus, astrovirus, norovirus GI, norovirus GII, and adenovirus) were compared with those of traditional microbial indicators, as well as environmental parameters (temperature, conductivity, salinity, pH, dissolved oxygen, total organic carbon, total suspended solids, turbidity, total nitrogen, and total phosphorus). Water samples were collected from surface waters of urban catchments in Singapore. Salmonella and P. aeruginosa had significant positive correlations with most of the microbial indicators, especially E. coli and enterococci. Norovirus GII showed moderately strong positive correlations with most of the microbial indicators, except for HPyVs and coliphages. In general, high geometric means and significant correlations between human-specific markers and pathogens suggest the possibility of sewage contamination in some areas. The simultaneous detection of human-specific markers (i.e., B. thetaiotaomicron, M. smithii, and HPyVs) with E. coli and enterococcus supports the likelihood of recent fecal contamination, since the human-specific markers are unable to regrow in natural surface waters. Multiple-linear-regression results further confirm that the inclusion of M. smithii and HPyVs, together with traditional indicators, would better predict the occurrence of pathogens. Further study is needed to determine the applicability of such models to different geographical locations and environmental conditions.


Subject(s)
Bacteria/isolation & purification , Feces/microbiology , Feces/virology , Quality Indicators, Health Care , Viruses/isolation & purification , Water Pollution , Humans , Singapore , Urban Population
5.
Water Res ; 58: 122-31, 2014 Jul 01.
Article in English | MEDLINE | ID: mdl-24747143

ABSTRACT

An assessment of the occurrence and concentration of enteric viruses and coliphages was carried out in highly urbanized catchment waters in the tropical city-state of Singapore. Target enteric viruses in this study were noroviruses, adenoviruses, astroviruses and rotaviruses. In total, 65 water samples were collected from canals and the reservoir of the Marina catchment on a monthly basis over a period of a year. Quantitative PCR (qPCR) and single agar layer plaque assay (SAL) were used to enumerate target enteric viruses and coliphages in water samples, respectively. The most prevalent pathogen were noroviruses, detected in 37 samples (57%), particularly norovirus genogroup II (48%), with a mean concentration of 3.7 × 10(2) gene copies per liter. Rotavirus was the second most prevalent virus (40%) with a mean concentration of 2.5 × 10(2) GC/L. The mean concentrations of somatic and male-specific coliphages were 2.2 × 10(2) and 1.1 × 10(2) PFU/100 ml, respectively. The occurrence and concentration of each target virus and the ratio of somatic to male-specific coliphages varied at different sampling sites in the catchment. For sampling sites with higher frequency of occurrence and concentration of viruses, the ratio of somatic to male-specific coliphages was generally much lower than other sampling sites with lower incidences of enteric viruses. Overall, higher statistical correlation was observed between target enteric viruses than between enteric viruses and coliphages. However, male-specific coliphages were positively correlated with norovirus concentrations. A multi-level integrated surveillance system, which comprises the monitoring of bacterial indicators, coliphages and selected enteric viruses, could help to meet recreational and surface water quality criteria in a complex urbanized catchment.


Subject(s)
Coliphages/isolation & purification , Enterovirus/isolation & purification , Fresh Water/virology , Water Microbiology , Adenoviridae/genetics , Adenoviridae/isolation & purification , Coliphages/genetics , Enterovirus/genetics , Environmental Monitoring , Norovirus/genetics , Norovirus/isolation & purification , Polymerase Chain Reaction , Recreation , Rotavirus/genetics , Rotavirus/isolation & purification , Seasons , Singapore , Tropical Climate , Urban Renewal , Water Quality
6.
Trop Med Int Health ; 19(3): 293-300, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24372706

ABSTRACT

OBJECTIVE: To determine whether gastroenteritis viruses and other enteric viruses could be detected in faecal specimens collected with Bio-wipes. METHODS: Faecal specimens, self-collected with Bio-wipes, from 190 individuals (94 diarrhoeal, 93 non-diarrhoeal, 3 unknown) were screened for eight human enteric viruses (enterovirus, hepatitis A virus, adenovirus, astrovirus, norovirus GI and GII, sapovirus and rotavirus) by real-time (reverse transcription)-polymerase chain reaction. Rotaviruses and noroviruses from positive specimens were genotyped. RESULTS: At least one enteric virus could be detected in 82.6% (157/190) of faecal specimens. Mixed infections of up to four different viruses could be detected in both diarrhoeal and non-diarrhoeal specimens. Enteroviruses were detected most frequently (63.7%), followed by adenoviruses (48.4%) and noroviruses (32.2%). Genotyping was successful for 78.6% of rotaviruses and 44.8% of noroviruses. CONCLUSIONS: Bio-wipes provide a user friendly, easier method for stool collection that facilitates enteric virus detection and genetic characterisation.


Subject(s)
Adenoviridae/isolation & purification , Diarrhea/virology , Feces/virology , Gastroenteritis/virology , RNA Viruses/isolation & purification , Specimen Handling/instrumentation , Adenoviridae/genetics , Adolescent , Adult , Aged , Aged, 80 and over , Child , Child, Preschool , Gastroenteritis/epidemiology , Genotyping Techniques/methods , Humans , Infant , Middle Aged , Phylogeny , RNA Viruses/genetics , Reverse Transcriptase Polymerase Chain Reaction/methods , Specimen Handling/methods , Young Adult
7.
Environ Sci Technol ; 46(2): 722-8, 2012 Jan 17.
Article in English | MEDLINE | ID: mdl-22129231

ABSTRACT

About half of the rural population of Cambodia lacks access to improved water; an even higher percentage lacks access to latrines. More than 35,000 concrete BioSand Water filters (BSF) have been installed in the country. However, the concrete BSF takes time to produce and weighs hundreds of pounds. A plastic BSF has been developed but may not perform to the same benchmarks established by its predecessor. To evaluate plastic BSF performance and health impact, we performed a cluster randomized controlled trial in 13 communities including 189 households and 1147 participants in the Angk Snoul district of Kandal Province from May to December 2008. The results suggest that villages with plastic BSFs had significantly lower concentrations of E. coli in drinking water and lower diarrheal disease (incidence rate ratio 0.41, 95% confidence interval: 0.24-0.69) compared to control villages. As one of the first studies on the plastic BSF in Cambodia, these are important findings, especially in a setting where the concrete BSF has seen high rates of continued use years after installation. The study suggests the plastic BSF may play an important role in scaling up the distribution/implementation of the BSF, potentially improving water quality and health in the region.


Subject(s)
Escherichia coli/isolation & purification , Filtration/instrumentation , Water Microbiology/standards , Water Purification/instrumentation , Bioreactors , Cambodia/epidemiology , Child , Child, Preschool , Diarrhea/epidemiology , Diarrhea/microbiology , Environmental Monitoring , Epidemiological Monitoring , Family Characteristics , Female , Filtration/methods , Humans , Incidence , Infant , Male , Silicon Dioxide , Water Supply/standards
8.
Water Res ; 45(14): 4092-102, 2011 Aug.
Article in English | MEDLINE | ID: mdl-21665239

ABSTRACT

The biosand filter (BSF) is a household slow sand filter that is operated intermittently such that an idle time of typically 18-22 h occurs in between daily charges of water. Virus attenuation during the idle time was investigated over repeated daily filtration cycles to capture the effect of media aging that encompasses processes occurring throughout the filter depth rather than restricted to the schmutzdecke at the media surface. A threshold aging period of about one to two weeks was required before virus attenuation began. The observed rates of MS2 and PRD-1 reduction were first-order and reached maxima of 0.061- and 0.053-log per hr, respectively, over seven-to-ten weeks. Suppression of microbial activity by sodium azide eliminated virus reduction during the idle time thus indicating that the operative media aging process was microbially mediated. The mechanism of virus reduction was not modification of media surfaces by physical/chemical or microbial processes. Instead, it appears that the activity of the microbial community within the filter is responsible. The most likely biological pathways are production of microbial exoproducts such as proteolytic enzymes or grazing of bacteria and higher microorganisms on virus particles. Implications of these findings for BSF design and operation and their relevance to other biological filtration technologies are discussed.


Subject(s)
Bacteriophage PRD1/isolation & purification , Filtration/methods , Levivirus/isolation & purification , Silicon Dioxide/chemistry , Water Microbiology , Water Purification/methods , Filtration/instrumentation , Household Articles , North Carolina , Sodium Azide/chemistry , Time Factors , Water Purification/instrumentation
9.
J Appl Microbiol ; 110(5): 1332-40, 2011 May.
Article in English | MEDLINE | ID: mdl-21410604

ABSTRACT

AIM: A new procedure was developed to recover adenovirus 41 in small volumes (1 l) of water samples based on adsorption, elution and evaporation. METHODS AND RESULTS: One litre of source water seeded with adenovirus 41 was adjusted to pH 3·5 and filtered using a large pore size (8·0 µm) negatively charged membrane filter (SCWP, 47 mm diameter, made of mixed-cellulose esters). Then, the filter was eluted using 4 ml of 1·5% beef extract plus 0·75% glycerol (pH 9·0). The eluate was reconcentrated to 0·1 ml or less volumes through evaporation assisted with air flow and heating at 55°C. Recovery of adenovirus 41 reached 55% under tested conditions and reduced filtration time by 85% in contrast to the widely used small pore size filter (0·45 µm pore size, 47 mm diameter). Reconcentration by evaporation achieved approx. 86·8% recovery from source water in approx. 1 h at no cost. CONCLUSION: The virus concentration method developed in this study is simple and cost-effective and can be used to efficiently recover adenovirus 41 from turbid water samples. SIGNIFICANCE AND IMPACT OF THE STUDY: The procedure developed can be applied to detect adenovirus 41 in source water within hours of sampling. In addition, this is the first application of evaporation to concentrate viruses in water samples.


Subject(s)
Adenoviridae/isolation & purification , Environmental Monitoring/methods , Microbiological Techniques/methods , Water Microbiology , Water/analysis , Adsorption , Environmental Monitoring/instrumentation , Filtration/instrumentation , Microbiological Techniques/instrumentation , Water Pollution/analysis , Water Supply/analysis
10.
Lett Appl Microbiol ; 52(2): 162-7, 2011 Feb.
Article in English | MEDLINE | ID: mdl-21214604

ABSTRACT

AIMS: To determine inactivation profiles of three human norovirus (NoV) surrogate viruses and coliphage MS2 by ultraviolet (UV) irradiation and the protective effect of cell association on UV inactivation. METHODS AND RESULTS: The inactivation rate for cell-free virus or intracellular echovirus 12 was determined by exposure to 254-nm UV light at fluence up to 100 mJ cm(-2) . The infectivity of murine norovirus (MNV), feline calicivirus (FCV) and echovirus 12 was determined by cell culture infectivity in susceptible host cell lines, and MS2 infectivity was plaque assayed on Escherichia coli host cells. The UV fluencies to achieve 4-log(10) inactivation were 25, 29, 30 and 70 (mJ cm(-2) ) for cell-free FCV, MNV, echovirus 12 and MS2, respectively. However, a UV fluence of 85 mJ cm(-2) was needed to inactivate intracellular echovirus 12 by 4 log(10) . CONCLUSIONS: Murine norovirus and echoviruses 12 are more conservative surrogates than FCV to predict the UV inactivation response of human NoV. Intracellular echovirus 12 was 2·8-fold more resistant to UV irradiation than cell-free one. SIGNIFICANCE AND IMPACT OF THE STUDY: Variation in UV susceptibilities among NoV surrogate viruses and a likely protective effect of cell association on virus susceptibility to UV irradiation should be considered for effective control of human NoV in water.


Subject(s)
Calicivirus, Feline/radiation effects , Enterovirus B, Human/radiation effects , Norovirus/radiation effects , Ultraviolet Rays , Animals , Cats , Cell Line , Levivirus/radiation effects
11.
J Appl Microbiol ; 110(4): 915-23, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21214694

ABSTRACT

AIMS: Escherichia coli is the pre-eminent microbiological indicator used to assess safety of drinking water globally. The cost and equipment requirements for processing samples by standard methods may limit the scale of water quality testing in technologically less developed countries and other resource-limited settings, however. We evaluate here the use of ambient-temperature incubation in detection of E. coli in drinking water samples as a potential cost-saving and convenience measure with applications in regions with high (>25°C) mean ambient temperatures. METHODS AND RESULTS: This study includes data from three separate water quality assessments: two in Cambodia and one in the Dominican Republic. Field samples of household drinking water were processed in duplicate by membrane filtration (Cambodia), Petrifilm™ (Cambodia) or Colilert® (Dominican Republic) on selective media at both standard incubation temperature (35­37°C) and ambient temperature, using up to three dilutions and three replicates at each dilution. Matched sample sets were well correlated with 80% of samples (n = 1037) within risk-based microbial count strata (E. coli CFU 100 ml−1 counts of <1, 1­10, 11­100, 101­1000, >1000), and a pooled coefficient of variation of 17% (95% CI 15­20%) for paired sample sets across all methods. CONCLUSIONS: These results suggest that ambient-temperature incubation of E. coli in at least some settings may yield sufficiently robust data for water safety monitoring where laboratory or incubator access is limited.


Subject(s)
Drinking Water/microbiology , Escherichia coli/isolation & purification , Temperature , Water Microbiology , Water Quality
12.
J Virol Methods ; 169(1): 8-12, 2010 Oct.
Article in English | MEDLINE | ID: mdl-20600332

ABSTRACT

RNA extraction from environmental samples yields frequently an RNA preparation containing inhibitors of molecular reactions. Commercial RNA extraction kits commonly permit extraction of only 0.1-0.2 ml sample volume. An RNA extraction buffer (RNAX buffer) was formulated for the extraction of viral RNA from 4.0 ml using a silica column based protocol. To evaluate the RNAX buffer based protocol, we used hepatitis A virus (HAV) and coxsackievirus B3 (CVB3) to monitor the RNA extraction efficiency from environmental samples. For evaluation of viral RNA recovery from water concentrates which were prepared from river and pond water by PEG concentration, serial ten fold dilutions of two waterborne viruses were added to the water concentrates for evaluation by quantitative detection. Quantitative recovery of HAV and CVB3 was determined by reverse transcriptase quantitative real-time PCR (RT-qPCR). The extracted RNA was compatible with RT-qPCR and sensitivity of detection of 0.8PFU per reaction was found with RNAX buffer and the developed protocol. This level of sensitivity was obtained using viral RNA extracted from 4.0 ml of an inoculated water sample concentrate. The RNAX buffer developed in this study could be applicable to the detection of other pathogens in water and food.


Subject(s)
Fresh Water/virology , RNA, Viral/isolation & purification , Reverse Transcriptase Polymerase Chain Reaction/methods , Virology/methods , Chromatography, Liquid/methods , Enterovirus B, Human/isolation & purification , Hepatitis A virus/isolation & purification , RNA, Viral/genetics , Sensitivity and Specificity , Silica Gel
13.
J Appl Microbiol ; 109(2): 635-641, 2010 Aug.
Article in English | MEDLINE | ID: mdl-20202019

ABSTRACT

AIM: To evaluate the electropositive, alumina nanofibre (NanoCeram) cartridge filter as a primary concentration method for recovering adenovirus, norovirus and male-specific coliphages from natural seawater. METHODS AND RESULTS: Viruses were concentrated from 40 l of natural seawater using a NanoCeram cartridge filter and eluted from the filter either by soaking the filter in eluent or by recirculating the eluent continuously through the filter using a peristaltic pump. The elution solution consisted of 3% beef extract and 0.1 mol l(-1) of glycine. The method using a peristaltic pump was more effective in removing the viruses from the filter. High recoveries of norovirus and male-specific coliphages (>96%) but not adenovirus (<3%) were observed from seawater. High adsorption to the filter was observed for adenovirus and male-specific coliphages (>98%). The adsorption and recovery of adenovirus and male-specific coliphages were also determined for fresh finished water and source water. CONCLUSION: The NanoCeram cartridge filter was an effective primary concentration method for the concentration of norovirus and male-specific coliphages from natural seawater, but not for adenovirus, in spite of the high adsorption of adenovirus to the filter. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates that NanoCeram cartridge filter is an effective primary method for concentrating noroviruses and male-specific coliphages from seawater, thereby simplifying collection and processing of water samples for virus recovery.


Subject(s)
Adenoviridae/isolation & purification , Coliphages/isolation & purification , Norovirus/isolation & purification , Seawater/virology , Water Purification/instrumentation , Adsorption , Aluminum Oxide/chemistry , Filtration/instrumentation , Fresh Water/virology , Nanostructures/chemistry , Water Microbiology
14.
Environ Technol ; 30(4): 379-91, 2009 Apr 01.
Article in English | MEDLINE | ID: mdl-19492549

ABSTRACT

Ceramic materials that can adsorb and/or inactivate viruses in water may find widespread application in low-tech drinking-water treatment technologies in developing countries, where porous ceramic filters and ceramic granular media filters are increasingly promoted for that purpose. We examined the adsorption and subsequent inactivation of bacteriophages MS2 and (phiX-174 on five ceramic media in batch adsorption studies to determine media suitability for use in a ceramic water filter application. The media examined were a kaolinitic ceramic medium and four kaolinitic ceramic media amended with iron or aluminium oxides that had been incorporated into the kaolinitic clays before firing. Batch adsorption tests indicate increased sorption and inactivation of surrogate viruses by media amended with Fe and Al oxide, with FeOOH-amended ceramic inactivating all bacteriophages up to 8 log10. Unmodified ceramic was a poor adsorbent of bacteriophages at less than 1 log10 adsorption-inactivation and high recovery of sorbed phages. These studies suggest that contact with ceramic media, modified with electropositive Fe or Al oxides, can reduce bacteriophages in waters to a greater extent than unmodified ceramic.


Subject(s)
Bacteriophage phi X 174/isolation & purification , Ceramics/chemistry , Fresh Water/chemistry , Levivirus/isolation & purification , Water Microbiology , Water Purification/methods , Adsorption , Aluminum Oxide/chemistry , Analysis of Variance , Ferric Compounds/chemistry , Hydrogen-Ion Concentration , Linear Models , Statistics, Nonparametric , Virus Inactivation
15.
J Water Health ; 7(3): 404-12, 2009 Sep.
Article in English | MEDLINE | ID: mdl-19491492

ABSTRACT

The effectiveness of point-of-use water treatment may be limited by declining use over time, particularly when water treatment is introduced via targeted intervention programmes. In order to evaluate the long-term uptake and use of locally produced ceramic water filters in rural Cambodia, we visited households that had received filters as part of NGO-subsidized distribution programmes over a 4 year period from 2002 to 2006. Of the more than 2,000 filters distributed, we visited 506 randomly selected households in 13 villages spanning three provinces to assess filter time in use and to collect data on factors potentially correlated with long-term use. Results indicate that filter use declined at the rate of approximately 2% per month after implementation, largely owing to breakages, and that, controlling for time since implementation, continued filter use over time was most closely positively associated with: related water, sanitation and hygiene practices in the home; cash investment in the technology by the household; and use of surface water as a primary drinking water source.


Subject(s)
Rural Population , Water Purification/methods , Water Supply , Cambodia , Female , Health Education , Humans , Male , Sanitation
16.
J Appl Microbiol ; 106(4): 1244-51, 2009 Apr.
Article in English | MEDLINE | ID: mdl-19187145

ABSTRACT

AIMS: To develop methods for recovering a model virus (bacteriophage MS2) from healthcare personal protective equipment (PPE). METHODS AND RESULTS: Nine eluents were evaluated for recovery of infectious MS2 from PPE: 1.5% beef extract (BE) pH 7.5 with and without 0.1% Tween 80, 1.5% BE pH 9.0 with and without 0.1% Tween 80, 3% BE pH 7.5 with and without 0.1% Tween 80, 3% BE pH 9.0 with and without 0.1% Tween 80 and PBS with 0.1% Tween 80. Methods were applied to experimentally contaminated PPE. Elution followed by two-step enrichment assay could recover virus inputs as low as 1.5 log(10), and could recover >90% of inoculated virus from used items of experimentally contaminated PPE worn by human volunteers. CONCLUSIONS: BE was effective for recovering infectious viruses from a range of PPE materials. SIGNIFICANCE AND IMPACT OF THE STUDY: PPE plays a crucial role in interrupting transmission of infectious agents from patients to healthcare workers (HCWs). The fate of micro-organisms when PPE is removed and disposed of has important consequences for infection control. Methods described here can be used to conduct rigorous studies of viral survival and transfer on PPE for risk assessments in infection control and HCW protection.


Subject(s)
Health Personnel , Protective Devices/virology , Viral Plaque Assay/methods , Viruses/isolation & purification , Humans , Virus Diseases/prevention & control , Viruses/growth & development
17.
Water Sci Technol ; 58(4): 757-63, 2008.
Article in English | MEDLINE | ID: mdl-18776609

ABSTRACT

Escherichia coli counts in household drinking water may or may not reliably indicate the presence of diarrheogenic pathogens originating in feces. The extent to which a bacterial indicator like E. coli predicts risks from all classes of pathogens (viruses and parasites as well as bacteria), especially in tropical waters, is uncertain. To investigate the association between E. coli in household drinking water and diarrheal diseases in Cambodia, we conducted a 22 week cohort study in a rural village in Kandal Province. Episodes of diarrhea (all) and bloody diarrhea (dysentery), water quality, water sources, and other covariates were monitored biweekly in 180 households. Households used a variety of water treatment, storage, and handling practices.Results suggest a weak but positive association between E. coli counts in household drinking water and diarrhea and for diarrhea with blood (dysentery), after adjusting for clustering within households and within individuals over time. Compared to households with <1 E. coli/100 ml in drinking water, there was no observed increased risk for having 1-10 E. coli/100 ml (LPR = 0.98, 95% CI 0.81-1.2 for diarrheal disease; LPR = 0.75, 95% CI 0.36-1.6 for dysentery). Households with measured E. coli of 11-100/100 ml did report increased diarrhea (LPR = 1.2, 95% CI 1.1-1.3 for diarrheal disease; LPR = 1.4, 95% CI 1.0-1.8 for dysentery), as did those with 101-1,000 E. coli/100 ml (LPR = 1.2, 95% CI 1.2-1.3 for diarrheal disease; LPR = 1.2, 95% CI 1.0-1.4 for dysentery) and those with >1,000 E. coli per 100 ml sample (LPR = 1.2, 95% CI 1.1-1.2 for diarrheal disease; LPR = 1.2, 95% CI 1.0-1.3 for dysentery). Unlike the results of some previous studies, diarrheal disease risks did not increase progressively in magnitude with increasing concentration of E. coli in drinking water.


Subject(s)
Diarrhea/microbiology , Escherichia coli/isolation & purification , Water Microbiology , Water Supply/analysis , Cambodia/epidemiology , Diarrhea/epidemiology , Risk Assessment
18.
Water Res ; 42(10-11): 2662-70, 2008 May.
Article in English | MEDLINE | ID: mdl-18281076

ABSTRACT

Point-of-use (POU) drinking water treatment technology enables those without access to safe water sources to improve the quality of their water by treating it in the home. One of the most promising emerging POU technologies is the biosand filter (BSF), a household-scale, intermittently operated slow sand filter. Over 500,000 people in developing countries currently use the filters to treat their drinking water. However, despite this successful implementation, there has been almost no systematic, process engineering research to substantiate the effectiveness of the BSF or to optimize its design and operation. The major objectives of this research were to: (1) gain an understanding of the hydraulic flow condition within the filter (2) characterize the ability of the BSF to reduce the concentration of enteric bacteria and viruses in water and (3) gain insight into the key parameters of filter operation and their effects on filter performance. Three 6-8 week microbial challenge experiments are reported herein in which local surface water was seeded with E. coli, echovirus type 12 and bacteriophages (MS2 and PRD-1) and charged to the filter daily. Tracer tests indicate that the BSF operated at hydraulic conditions closely resembling plug flow. The performance of the filter in reducing microbial concentrations was highly dependent upon (1) filter ripening over weeks of operation and (2) the daily volume charged to the filter. BSF performance was best when less than one pore volume (18.3-L in the filter design studied) was charged to the filter per day and this has important implications for filter design and operation. Enhanced filter performance due to ripening was generally observed after roughly 30 days. Reductions of E. coli B ranged from 0.3 log10 (50%) to 4 log10, with geometric mean reductions after at least 30 days of operation of 1.9 log10. Echovirus 12 reductions were comparable to those for E. coli B with a range of 1 log10 to >3 log10 and mean reductions after 30 days of 2.1 log10. Bacteriophage reductions were much lower, ranging from zero to 1.3 log10 (95%) with mean reductions of only 0.5 log10 (70%). These data indicate that virus reduction by BSF may differ substantially depending upon the specific viral agent.


Subject(s)
Bacteriophages/isolation & purification , Enterovirus B, Human/isolation & purification , Escherichia coli/isolation & purification , Filtration/instrumentation , Household Articles , Silicon Dioxide , Nephelometry and Turbidimetry , Porosity , Water Microbiology
19.
J Appl Microbiol ; 104(4): 1203-12, 2008 Apr.
Article in English | MEDLINE | ID: mdl-18028362

ABSTRACT

AIMS: To evaluate a PCR-based detection and typing method for faecal indicator viruses (F+ RNA coliphages) in water and shellfish, and apply the method for better understanding of the ecology and microbial source tracking potential of these viruses. METHODS AND RESULTS: Water and shellfish samples were collected over 3 years at nine estuaries in the East, West and Gulf Coasts of the USA, providing 1033 F+ RNA coliphage isolates. F+ RNA coliphage genotyping rates by reverse transcriptase-PCR-reverse line blot (RLB) hybridization ranged from 94.7% to 100% among estuaries, and were not significantly different in oysters, clams, mussels or water (P = 0.8427). Twenty samples negative by RLB were nucleotide sequenced for confirmation, and to refine RLB probes. More F+ RNA coliphages were genotyped from colder water than warmer waters, while the water salinity did not affect F+ RNA coliphage levels. CONCLUSIONS: RT-PCR-RLB was a robust method for detecting and genotyping F+ RNA coliphages from diverse coastal areas, which provided new information on the ecology of F+ RNA coliphages. SIGNIFICANCE AND IMPACT OF THE STUDY: This performance-validated F+ RNA coliphage method can be used for faecal indicator monitoring and microbial source tracking, to protect recreational bathers and shellfish consumers from exposure to pathogenic virus and their disease risks.


Subject(s)
Coliphages/isolation & purification , Feces/virology , Mollusca/virology , RNA Phages/isolation & purification , Water Microbiology , Animals , Coliphages/genetics , Genotype , Nucleic Acid Hybridization/methods , Phylogeny , RNA Phages/genetics , Reverse Transcriptase Polymerase Chain Reaction/methods , United States
20.
J Appl Microbiol ; 101(5): 1015-26, 2006 Nov.
Article in English | MEDLINE | ID: mdl-17040225

ABSTRACT

AIMS: The utility of coliphages to detect and track faecal pollution was evaluated using South Carolina surface waters that exceeded State faecal coliform standards. METHODS AND RESULTS: Coliphages were isolated from 117 surface water samples by single agar layer (SAL) and enrichment presence/absence (EP/A) methods. Confirmed F+ RNA coliphages were typed for microbial source tracking using a library-independent approach. Concentrations of somatic coliphages using 37 and 44.5 degrees C incubation temperatures were found to be significantly different and the higher temperature may be more specific for faecal contamination. The EP/A technique detected coliphages infecting Escherichia coli Famp in 38 (66%) of the 58 surface water samples negative for F+ coliphages by the SAL method. However, coliphages isolated by EP/A were found to be less representative of coliphage diversity within a sample. Among the 2939 coliphage isolates tested from surface water and known source samples, 813 (28%) were found to be F+ RNA. The majority (94%) of surface water F+ RNA coliphage isolates typed as group I. Group II and/or III viruses were identified from 14 surface water stations, the majority of which were downstream of wastewater discharges. These sites were likely contaminated by human-source faecal pollution. CONCLUSIONS: The results suggest that faecal contamination in surface waters can be detected and source identifications aided by coliphage analyses. SIGNIFICANCE AND IMPACT OF THE STUDY: This study supports the premise that coliphage typing can provide useful, but not absolute, information to distinguish human from animal sources of faecal pollution. Furthermore, the comparison of coliphage isolation methods detailed in this study should provide valuable information to those wishing to incorporate coliphage detection into water quality assessments.


Subject(s)
Coliphages/classification , Feces/virology , Water Microbiology , Animals , Coliphages/genetics , Coliphages/isolation & purification , Environmental Monitoring/methods , Humans , RNA, Viral/analysis , Temperature
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