Towards a unified system for detecting waterborne pathogens

A narrative review of wastewater surveillance: pathogens of concern, applications, detection methods, and challenges

Introduction

The emergence and resurgence of pathogens have led to significant global health challenges. Wastewater surveillance has historically been used to track water-borne or fecal-orally transmitted pathogens, providing a sensitive means of monitoring pathogens within a community. This technique offers a comprehensive, real-time, and cost-effective approach to disease surveillance, especially for diseases that are difficult to monitor through individual clinical screenings.

Methods

This narrative review examines the current state of knowledge on wastewater surveillance, emphasizing important findings and techniques used to detect potential pathogens from wastewater. It includes a review of literature on the detection methods, the pathogens of concern, and the challenges faced in the surveillance process.

Results

Wastewater surveillance has proven to be a powerful tool for early warning and timely intervention of infectious diseases. It can detect pathogens shed by asymptomatic and pre-symptomatic individuals, providing an accurate population-level view of disease transmission. The review highlights the applications of wastewater surveillance in tracking key pathogens of concern, such as gastrointestinal pathogens, respiratory pathogens, and viruses like SARS-CoV-2.

Discussion

The review discusses the benefits of wastewater surveillance in public health, particularly its role in enhancing existing systems for infectious disease surveillance. It also addresses the challenges faced, such as the need for improved detection methods and the management of antimicrobial resistance. The potential for wastewater surveillance to inform public health mitigation strategies and outbreak response protocols is emphasized.

Conclusion

Wastewater surveillance is a valuable tool in the fight against infectious diseases. It offers a unique perspective on the spread and evolution of pathogens, aiding in the prevention and control of disease epidemics. This review underscores the importance of continued research and development in this field to overcome current challenges and maximize the potential of wastewater surveillance in public health.

Wastewater-borne viruses and bacteria, surveillance and biosensors at the interface of academia and field deployment

Wastewater is a complex, but an ideal, matrix for disease monitoring and surveillance as it represents the entire load of enteric pathogens from a local catchment area. It captures both clinical and community disease burdens. Global interest in wastewater surveillance has been growing rapidly for infectious diseases monitoring and for providing an early warning of potential outbreaks. Although molecular detection methods show high sensitivity and specificity in pathogen monitoring from wastewater, they are strongly limited by challenges, including expensive laboratory settings and prolonged sample processing and analysis. Alternatively, biosensors exhibit a wide range of practical utility in real-time monitoring of biological and chemical markers. However, field deployment of biosensors is primarily challenged by prolonged sample processing and pathogen concentration steps due to complex wastewater matrices. This review summarizes the role of wastewater surveillance and provides an overview of infectious viral and bacterial pathogens with cutting-edge technologies for their detection. It emphasizes the practical utility of biosensors in pathogen monitoring and the major bottlenecks for wastewater surveillance of pathogens, and overcoming approaches to field deployment of biosensors for real-time pathogen detection. Furthermore, the promising potential of novel machine learning algorithms to resolve uncertainties in wastewater data is discussed.

The escalating threat of human-associated infectious bacteria in surface aquatic resources: Insights into prevalence, antibiotic resistance, survival mechanisms, detection, and prevention strategies

Anthropogenic activities and climate change profoundly impact water quality, leading to a concerning increase in the prevalence and abundance of bacterial pathogens across diverse aquatic environments. This rise has resulted in a growing challenge concerning the safety of water sources, particularly surface waters and marine environments. This comprehensive review delves into the multifaceted challenges presented by bacterial pathogens, emphasizing threads to human health within ground and surface waters, including marine ecosystems. The exploration encompasses the intricate survival mechanisms employed by bacterial pathogens and the proliferation of antimicrobial resistance, largely driven by human-generated antibiotic contamination in aquatic systems. The review further addresses prevalent pathogenic bacteria, elucidating associated risk factors, exploring their eco-physiology, and discussing the production of potent toxins. The spectrum of detection techniques, ranging from conventional to cutting-edge molecular approaches, is thoroughly examined to underscore their significance in identifying and understanding waterborne bacterial pathogens. A critical aspect highlighted in this review is the imperative for real-time monitoring of biomarkers associated with waterborne bacterial pathogens. This monitoring serves as an early warning system, facilitating the swift implementation of action plans to preserve and protect global water resources. In conclusion, this comprehensive review provides fresh insights and perspectives, emphasizing the paramount importance of preserving the quality of aquatic resources to safeguard human health on a global scale.

Passive Sampler Technology for Viral Detection in Wastewater-Based Surveillance: Current State and Nanomaterial Opportunities

Although wastewater-based surveillance (WBS) is an efficient community-wide surveillance tool, its implementation for pathogen surveillance remains limited by ineffective sample treatment procedures, as the complex composition of wastewater often interferes with biomarker recovery. Moreover, current sampling protocols based on grab samples are susceptible to fluctuant biomarker concentrations and may increase operative costs, often rendering such systems inaccessible to communities in low-to-middle-income countries (LMICs). As a response, passive samplers have emerged as a way to make wastewater sampling more efficient and obtain more reliable, consistent data. Therefore, this study aims to review recent developments in passive sampling technologies to provide researchers with the tools to develop novel passive sampling strategies. Although promising advances in the development of nanostructured passive samplers have been reported, optimization remains a significant area of opportunity for researchers in the area, as methods for flexible, robust adsorption and recovery of viral genetic materials would greatly improve the efficacy of WBS systems while making them more accessible for communities worldwide.

Opportunistic Pathogens of Recreational Waters with Emphasis on Antimicrobial Resistance-A Possible Subject of Human Health Concern

Infections caused by exposure to opportunistic pathogens can cause serious health problems during recreational water use. The problem of diseases caused by microbes transmitted by water is a major public health challenge, especially in developing countries with economic problems and poor hygiene conditions. Moreover, the quality of water in natural reservoirs is often at a very low level in terms of microbiological water purity, which means that their use for recreational purposes, but also as a source of drinking water, may have serious health consequences. Recreational waters pose a threat to human health. Therefore, the quality of recreational waters is closely monitored in many jurisdictions. In this review, we summarize key information on the most common pathogens that can be water-based or waterborne. The issue of antimicrobial resistance among opportunistic pathogens remains equally important. It is important not only to fight pathogens, but also to take action to reduce chemical stressors (especially antibiotics) in the aquatic environment, and to understand the various mechanisms of the spread of antibiotic-resistant genes.

Incidence of human associated HF183 Bacteroides marker and E. coli levels in New Orleans Canals

With a focus on five sites in an impaired, densely populated area in the New Orleans area, we investigated the temporal and spatial variability of standard FIB and a marker of human-associated pollution (Bacteroides HF183). With all sites combined, only a weak positive correlation (r = 0.345; p = 0.001) was observed between E. coli and HF183. Also, specific conductivity (r = - 0.374; p < 0.0001) and dissolved oxygen (r = - 0.390; p < 0.0001) were observed to show a weak moderate correlation with E. coli. These correlations increased to moderately negative when HF183 was correlated with specific conductivity (r = - 0.448; p < 0.0001) and dissolved oxygen (r = - 0.455; p < 0.0001). E. coli contamination was generally highest at the sites in the canal that are situated in the most densely populated part of the watershed while HF183 was frequently detected across all sites. E. coli concentrations were significantly higher (p < 0.05) when HF183 was present. HF183 was detected at significantly higher concentrations in samples that exceeded the EPA water quality standard (WQS) than those that did not (p < 0.05). Dissolved oxygen and specific conductivity were significantly lower when E. coli WQS was exceeded or when HF183 was present (p < 0.05). Rainfall impacted E. coli concentrations and HF183 differently at the study sites. While HF183 and E. coli concentrations levels were significantly higher (p < 0.05) if the days prior to sampling had been wet, the frequency of detection of HF183 was unimpacted, as comparable detection rates were recorded during wet and dry weather conditions. Without testing for HF183, it would have been assumed, based on testing for E. coli alone, that human fecal pollution was only associated with densely populated areas and rainfall events. E. coli alone may not be an effective indicator of sewage pollution at the study sites across all weather conditions and may need to be complemented with HF183 enumeration to optimize human fecal pollution identification and management at the watershed level.

Loop-mediated isothermal amplification (LAMP): a sensitive molecular tool for detection of Staphylococcus aureus in meat and dairy product

Staphylococcus aureus-mediated food poisoning is a primary concern worldwide. The presence of the organism in food is an indicative of poor sanitation during production, and it is essential to have efficient methods for detecting this pathogen. A novel molecular diagnostic technique called loop-mediated isothermal amplification (LAMP) serves as a rapid and sensitive detection method, which amplifies nucleic acids at isothermal conditions. In this study, a LAMP-based diagnostic assay was developed to detect Staphylococcus aureus (S. aureus) using two target genes femA and arcC. The optimum reaction temperature was found to be 65 °C and at 60 °C for femA and arcC genes, respectively. The developed assay specifically amplified DNA from S. aureus, not from other related bacterial species and compared to PCR, and a 100-fold higher sensitivity was observed. Furthermore, the LAMP assay could detect the pathogen from food samples mainly meat and dairy samples when analyzed in both intact and enriched conditions. Thirteen samples were found positive for S. aureus with LAMP showing a greater number of positive samples in comparison to PCR. This study established a highly sensitive and a rapid diagnostic procedure for the detection and surveillance of this major foodborne pathogen.

The bacterial community composition and its environmental drivers in the rivers around eutrophic Chaohu Lake, China

Background

Bacterial community play a key role in environmental and ecological processes in river ecosystems. Rivers are used as receiving body for treated and untreated urban wastewaters that brings high loads of sewage and excrement bacteria. However, little is known about the bacterial community structure and functional files in the rivers around the eutrophic Chaohu Lake, the fifth largest freshwater lake in China, has been subjected to severe eutrophication and cyanobacterial blooms over the past few decades. Therefore, understanding the taxonomic and functional compositions of bacterial communities in the river will contribute to understanding aquatic microbial ecology. The main aims were to (1) examine the structure of bacterial communities and functional profiles in this system; (2) find the environmental factors of bacterial community variations.

Results

We studied 88 sites at rivers in the Chaohu Lake basin, and determined bacterial communities using Illumina Miseq sequencing of the 16 S rRNA gene, and predicted functional profiles using PICRUSt2. A total of 3,390,497 bacterial 16 S rRNA gene sequences were obtained, representing 17 phyla, and 424 genera; The dominant phyla present in all samples were Bacteroidetes (1.4-82.50 %), followed by Proteobacteria (12.6–97.30 %), Actinobacteria (0.1–17.20 %). Flavobacterium was the most numerous genera, and accounted for 0.12–80.34 % of assigned 16 S reads, followed by Acinetobacter (0.33–49.28 %). Other dominant bacterial genera including Massilia (0.06–25.40 %), Psychrobacter (0-36.23 %), Chryseobacterium (0.01–22.86 %), Brevundimonas (0.01–12.82 %), Pseudomonas (0-59.73 %), Duganella (0.08–23.37 %), Unidentified Micrococcaceae (0-8.49 %). The functional profiles of the bacterial populations indicated an relation with many human diseases, including infectious diseases. Overall results, using the β diversity measures, coupled with heatmap and RDA showed that there were spatial variations in the bacterial community composition at river sites, and Chemical oxygen demand (COD_Mn) and (NH₄⁺ )were the dominant environmental drivers affecting the bacterial community variance.

Conclusions

The high proportion of the opportunistic pathogens (Acinetobacter, Massilia, Brevundimonas) indicated that the discharge of sewage without adequate treatment into the rivers around Chaohu Lake. We propose that these bacteria could be more effective bioindicators for long-term sewage monitoring in eutrophic lakes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02252-9.

Water safety screening via multiplex LAMP-Au-nanoprobe integrated approach

Contaminated water resources remain a major global concern regarding public health. The majority of water safety protocols include indicators of microbial contamination to evaluate the potential risk to public health and are key elements of quality guidelines. Among these, markers for total coliforms and fecal coliforms are strong indicators of co-contamination with other pathogens. Traditional methods, recurring to slow and cumbersome culture-based approaches, have been gradually replaced by molecular methods, capable of faster and more specific screening. These are usually PCR-based methods that may allow for multiple pathogen detection but require dedicated laboratory equipment, hindering the rapid on-site assessment. Here, we used a multiplex Loop-Mediated Isothermal Amplification (mLAMP) strategy for the amplification of two markers associated with the contamination by total and fecal coliforms (e.g. Escherichia coli) - lacZ and uidA genes, respectively - thus allowing for single tube multiplex detection. The mLAMP products were then subject to an Au-nanoprobe colorimetric detection assay for precise discrimination of targets. This approach was validated in 22 water samples that were also screened for the presence of lacZ and uidA using standard and quantitative PCR, with the capability for discriminating the contamination level, e.g. a semi-quantitative evaluation of water quality.

Measuring Environmental Exposure to Enteric Pathogens in Low-Income Settings: Review and Recommendations of an Interdisciplinary Working Group

Infections with enteric pathogens impose a heavy disease burden, especially among young children in low-income countries. Recent findings from randomized controlled trials of water, sanitation, and hygiene interventions have raised questions about current methods for assessing environmental exposure to enteric pathogens. Approaches for estimating sources and doses of exposure suffer from a number of shortcomings, including reliance on imperfect indicators of fecal contamination instead of actual pathogens and estimating exposure indirectly from imprecise measurements of pathogens in the environment and human interaction therewith. These shortcomings limit the potential for effective surveillance of exposures, identification of important sources and modes of transmission, and evaluation of the effectiveness of interventions. In this review, we summarize current and emerging approaches used to characterize enteric pathogen hazards in different environmental media as well as human interaction with those media (external measures of exposure), and review methods that measure human infection with enteric pathogens as a proxy for past exposure (internal measures of exposure). We draw from lessons learned in other areas of environmental health to highlight how external and internal measures of exposure can be used to more comprehensively assess exposure. We conclude by recommending strategies for advancing enteric pathogen exposure assessments.

Evaluation of 3M™ loop-mediated isothermal amplification-based kit and 3M™ ready-to-use plating system for detection of Listeria in naturally contaminated leafy vegetables, chicken, and their related processing environments

The effectiveness of two different rapid methods involving the 3M™ molecular detection assay Listeria and the 3M™ Petrifilm environmental Listeria Plate were evaluated for the rapid detection of Listeria from naturally contaminated vegetables and chicken-processing environments against the standard culture-based method. A total of 178 samples were examined for the presence of Listeria. A total of 47/178 (26.4%) by standard ISO culture-based method (EN ISO 11290-1), 42/178 (23.6%) by 3M™ MDA Listeria and 40/178 (22.5%) by 3M™ Petrifilm EL Plate showed positive results, respectively. The accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for 3M™ MDA Listeria and 3M™ Petrifilm EL Plate were 97.2, 89.4, 99.3, 97.7, 96.4% and 96.1, 85.1, 100.0, 100.0, 94.9%, respectively. Based on the Cohen's Kappa value, there was a complete and robust concordance between 3M™ MDA Listeria (0.911) and 3M™ Petrifilm EL Plates (0.894) as compared to the standard culture-based method.

Synthesis and application of superabsorbent polymer microspheres for rapid concentration and quantification of microbial pathogens in ambient water

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A portable, hand-pressed 3D-printed system with SAP microspheres was developed.

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This system could achieve efficient concentration of environmental microorganisms.

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Superior performance was achieved with varying ionic strengths in a short time.

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Optimized SAP microspheres could be reused 20 times with simple procedures.

Even though numerous methods have been developed for the detection and quantification of waterborne pathogens, the application of these methods is often hindered by the very low pathogen concentrations in natural waters. Therefore, rapid and efficient sample concentration methods are urgently needed. Here we present a novel method to pre-concentrate microbial pathogens in water using a portable 3D-printed system with super-absorbent polymer (SAP) microspheres, which can effectively reduce the actual volume of water in a collected sample. The SAP microspheres absorb water while excluding bacteria and viruses by size exclusion and charge repulsion. To improve the water absorption capacity of SAP in varying ionic strength waters (0–100 mM), we optimized the formulation of SAP to 180 g⋅L⁻¹ Acrylamide, 75 g⋅L⁻¹ Itaconic Acid and 4.0 g⋅L⁻¹ Bis-Acrylamide for the highest ionic strength water as a function of the extent of cross-linking and the concentration of counter ions. Fluorescence microscopy and double-layer agar plating respectively showed that the 3D-printed system with optimally-designed SAP microspheres could rapidly achieve a 10-fold increase in the concentration of Escherichia coli (E. coli) and bacteriophage MS2 within 20 min with concentration efficiencies of 87% and 96%, respectively. Fold changes between concentrated and original samples from qPCR and RT-qPCR results were found to be respectively 11.34–22.27 for E. coli with original concentrations from 10⁴ to 10⁶ cell·mL⁻¹, and 8.20–13.81 for MS2 with original concentrations from 10⁴ to 10⁶ PFU·mL⁻¹. Furthermore, SAP microspheres can be reused for 20 times without performance loss, significantly decreasing the cost of our concentration system.

Molecular identification of biological contaminants in different drinking water resources of the Jazan region, Saudi Arabia

Drinking water quality plays a remarkable role in human infections and diseases. This study used polymerase chain reaction (PCR) techniques to detect bacterial pathogens. In addition, a physicochemical analysis was performed on drinking water samples from several sources. A total of 123 drinking water samples were collected from different areas in the Jazan region in Saudi Arabia: ground water (40 samples), bottled water (15 samples), tap water (52 samples), and water purification shops (16 samples). To isolate the bacterial pathogens, the water samples were spread on Nutrient and MacConkey agar media, and the grown pathogens were then identified by the 16S ribosomal RNA technique. In 87 (70.7%) of the 123 drinking water samples, there was no pathogen growth on the two-culture medium. However, 36 (29.3%) of the samples were found to be contaminated with bacteria. The physicochemical analysis indicated that the water samples were within the Saudi drinking water standards. The bacteria were resistant to Cefotaxime, Cefotaxime/Clavulanic acid, Erythromycin, Penicillin G, Rifampin and Sulfamethoxazole-Trimethoprim, respectively. The findings suggest that in Jazan, bottled water is a safer source of potable water than tap water. The contamination in the water may be occurring at the reservoirs rather than the water sources.

Patterns of sediment-associated fecal indicator bacteria in an urban estuary: Benthic-pelagic coupling and implications for shoreline water quality

Estuarine and coastal waterways are commonly monitored for fecal and sewage contamination to protect recreator health and ecosystem functions. Such monitoring programs commonly rely on cultivation-based counts of fecal indicator bacteria (FIB) in water column samples. Recent studies demonstrate that sediments and beach sands can be heavily colonized by FIB, and that settling and resuspension of colonized particles may significantly influence the distribution of FIB in the water column. However, measurements of sediment FIB are rarely incorporated into monitoring programs, and geographic surveys of sediment FIB are uncommon. In this study, the distribution of FIB and the extent of benthic-pelagic FIB coupling were examined in the urbanized, lower Hudson River Estuary. Using cultivation-based enumeration, two commonly-measured FIB, enterococci and Escherichia coli, were widely distributed in both sediment and water, and were positively correlated with each other. The taxonomic identity of FIB isolates from water and sediment was confirmed by DNA sequencing. The geometric mean of FIB concentration in sediment was correlated with both the geometric mean of FIB in water samples from the same locations and with sediment organic carbon. These two positive associations likely reflect water as the FIB source for underlying sediments, and longer FIB persistence in the sediments compared to the water, respectively. The relative representation of other fecal associated bacterial genera in sediment, determined by 16S rRNA gene sequencing, increased with the sequence representation of the two FIB, supporting the value of these FIB for assessing sediment contamination. Experimental resuspension of sediment increased shoreline water column FIB concentrations, which may explain why shoreline water samples had higher average FIB concentrations than samples collected nearby but further from shore. In combination, these results demonstrate extensive benthic-pelagic coupling of FIB in an urbanized estuary and highlight the importance of sediment FIB distribution and ecology when interpreting water quality monitoring data.

Weather, environmental conditions, and waterborne Giardia and Cryptosporidium in Iqaluit, Nunavut

Indigenous communities in the Arctic often face unique drinking water quality challenges related to inadequate infrastructure and environmental contamination; however, limited research exists on waterborne parasites in these communities. This study examined Giardia and Cryptosporidium in untreated surface water used for drinking in Iqaluit, Canada. Water samples (n = 55) were collected weekly from June to September 2016 and tested for the presence of Giardia and Cryptosporidium using microscopy and polymerase chain reaction (PCR). Exact logistic regressions were used to examine associations between parasite presence and environmental exposure variables. Using microscopy, 20.0% of samples tested positive for Giardia (n = 11) and 1.8% of samples tested positive for Cryptosporidium (n = 1). Low water temperatures (1.1 to 6.7 °C) and low air temperatures (-0.1 to 4.5 °C) were significantly associated with an increased odds of parasite presence (p = 0.047, p = 0.041, respectively). These results suggest that surface water contamination with Giardia and Cryptosporidium may be lower in Iqaluit than in other Canadian regions; however, further research should examine the molecular characterization of waterborne parasites to evaluate the potential human health implications in Northern Canada.

Potential human pathogenic bacteria in five hot springs in Eritrea revealed by next generation sequencing

Human pathogens can survive and grow in hot springs. For water quality assessment, Escherichia coli or Enterococci are the main thermotolerant enteric bacteria commonly used to estimate the load of pathogenic bacteria in water. However, most of the environmental bacteria are unculturable thus culture methods may cause bias in detection of most pathogens. Illumina sequencing can provide a more comprehensive and accurate insight into environmental bacterial pathogens, which can be used to develop better risk assessment methods and promote public health awareness. In this study, high-throughput Illumina sequencing was used to identify bacterial pathogens from five hot springs; Maiwooi, Akwar, Garbanabra, Elegedi and Gelti, in Eritrea. Water samples were collected from the five hot springs. Total community DNA was extracted from samples using the phenol-chloroform method. The 16S rRNA gene variable region (V4—V7) of the extracted DNA was amplified and library construction done according to Illumina sequencing protocol. The sequence reads (length >200 bp) from Illumina sequencing libraries ranged from 22,091 sequences in the wet sediment sample from Garbanabra to 155,789 sequences in the mat sample from Elegedi. Taxonomy was assigned to each OTU using BLASTn against a curated database derived from GreenGenes, RDPII, SILVA SSU Reference 119 and NCBI. The proportion of potential pathogens from the water samples was highest in Maiwooi (17.8%), followed by Gelti (16.7%), Akwar (13.6%) and Garbanabra (10.9%). Although the numbers of DNA sequence reads from Illumina sequencing were very high for the Elegedi (104,328), corresponding proportion of potential pathogens very low (3.6%). Most of the potential pathogenic bacterial sequences identified were from Proteobacteria and Firmicutes. Legionella and Clostridium were the most common detected genera with different species. Most of the potential pathogens were detected from the water samples. However, sequences belonging to Clostridium were observed more abundantly from the mat samples. This study employed high-throughput sequencing technologies to determine the presence of pathogenic bacteria in the five hot springs in Eritrea.

Infectious diarrheal disease caused by contaminated well water in Chinese schools: A systematic review and meta-analysis

Background

In China, waterborne outbreaks of infectious diarrheal disease mainly occur in schools, and contaminated well water is a common source of pathogens. The objective of this review was to present the attack rates, durations of outbreak, pathogens of infectious diarrheal disease, and sanitary conditions of wells in primary and secondary schools in China, and to analyze risk factors and susceptibility of school children.

Methods

Relevant articles and reports were identified by searching PubMed, Web of Science, China National Knowledge Infrastructure, China Information System for Disease Control and Prevention, and the Chinese Field Epidemiology Training Program. Essential information, including urban/rural areas, school types, attack rates, pathogens, durations of outbreak, report intervals, and interventions were extracted from the eligible articles. Wilcoxon signed-rank test, Kruskal–Wallis H test, and Spearman correlation test were conducted in statistical analyses. Sex- and age-specific attack rate ratios were calculated as pooled effect sizes.

Results

We screened 2188 articles and retrieved data of 85 outbreaks from 1987 to 2014. Attack rates of outbreaks in rural areas (median, 12.63 cases/100 persons) and in primary schools (median, 14.54 cases/100 persons) were higher than those in urban areas (median, 5.62 cases/100 persons) and in secondary schools (median, 8.74 cases/100 persons) (P = 0.004 and P = 0.013, respectively). Shigella, pathogenic Escherichia coli, and norovirus were the most common pathogens. Boys tended toward higher attack rates than girls (sex-specific attack rate ratio, 1.13; 95% CI, 1.00–1.29, P = 0.05). Unsanitary conditions of water wells were reported frequently, and unhealthy behavior habits were common in students.

Conclusion

School children were susceptible to waterborne disease in China. Chinese government should make efforts to improve access to safe water in schools. Health education promotion and conscientiousness of school leaders and teachers should be enhanced.

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School children were susceptible to waterborne disease in China.

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Attack rates of rural or primary schools were high.

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Boys trended toward higher risk than girls.

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Unsanitary conditions of water wells were reported frequently.

Recent developments in detection and enumeration of waterborne bacteria: a retrospective minireview

Waterborne diseases have emerged as global health problems and their rapid and sensitive detection in environmental water samples is of great importance. Bacterial identification and enumeration in water samples is significant as it helps to maintain safe drinking water for public consumption. Culture‐based methods are laborious, time‐consuming, and yield false‐positive results, whereas viable but nonculturable (VBNCs) microorganisms cannot be recovered. Hence, numerous methods have been developed for rapid detection and quantification of waterborne pathogenic bacteria in water. These rapid methods can be classified into nucleic acid‐based, immunology‐based, and biosensor‐based detection methods. This review summarizes the principle and current state of rapid methods for the monitoring and detection of waterborne bacterial pathogens. Rapid methods outlined are polymerase chain reaction (PCR), digital droplet PCR, real‐time PCR, multiplex PCR, DNA microarray, Next‐generation sequencing (pyrosequencing, Illumina technology and genomics), and fluorescence in situ hybridization that are categorized as nucleic acid‐based methods. Enzyme‐linked immunosorbent assay (ELISA) and immunofluorescence are classified into immunology‐based methods. Optical, electrochemical, and mass‐based biosensors are grouped into biosensor‐based methods. Overall, these methods are sensitive, specific, time‐effective, and important in prevention and diagnosis of waterborne bacterial diseases.

Seasonal distribution and prevalence of diarrheagenic Escherichia coli in different aquatic environments in Taiwan

Diarrheagenic Escherichia coli (DEC) are the most common agents of diarrhea. Waterborne DEC could pose a potential health risk to human through agricultural, household, recreational, and industrial use. There are few published reports on the detection of DEC and its seasonal distribution in aquatic environments. The presence of DEC in different types of aquatic environments was investigated in this study. Water samples were collected from major rivers, water reservoirs, and recreational hot springs throughout Taiwan. Moreover, an intensive water sampling plan was carried out along Puzih River. The detection of DEC target genes was used to determine the presence of enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), and Shiga toxin-producing E. coli (STEC). Among the 383 water samples analyzed, DEC was found in 122 (31.8%) samples. The detection rate varied by genotype, raging from 3.6% for STEC to 17.2% for EPEC. The DEC detection rate was higher from river waters than reservoirs and hot springs. In addition, DEC was detected at a higher rate in spring and summer. The presence of EPEC was significantly associated with total coliform levels among hot spring samples. Moreover, the presence of ETEC in river water samples was associated with heterotrophic plate counts. Water with EPEC differed significantly in pH from Puzih River samples. These results suggest that seasonal characteristics may affect the presence of DEC in different aquatic environments, and water quality indicators may be indicative of the presence of DEC.

Ultrafiltration and Microarray for Detection of Microbial Source Tracking Marker and Pathogen Genes in Riverine and Marine Systems

Pathogen identification and microbial source tracking (MST) to identify sources of fecal pollution improve evaluation of water quality. They contribute to improved assessment of human health risks and remediation of pollution sources. An MST microarray was used to simultaneously detect genes for multiple pathogens and indicators of fecal pollution in freshwater, marine water, sewage-contaminated freshwater and marine water, and treated wastewater. Dead-end ultrafiltration (DEUF) was used to concentrate organisms from water samples, yielding a recovery efficiency of >95% for Escherichia coli and human polyomavirus. Whole-genome amplification (WGA) increased gene copies from ultrafiltered samples and increased the sensitivity of the microarray. Viruses (adenovirus, bocavirus, hepatitis A virus, and human polyomaviruses) were detected in sewage-contaminated samples. Pathogens such as Legionella pneumophila, Shigella flexneri, and Campylobacter fetus were detected along with genes conferring resistance to aminoglycosides, beta-lactams, and tetracycline. Nonmetric dimensional analysis of MST marker genes grouped sewage-spiked freshwater and marine samples with sewage and apart from other fecal sources. The sensitivity (percent true positives) of the microarray probes for gene targets anticipated in sewage was 51 to 57% and was lower than the specificity (percent true negatives; 79 to 81%). A linear relationship between gene copies determined by quantitative PCR and microarray fluorescence was found, indicating the semiquantitative nature of the MST microarray. These results indicate that ultrafiltration coupled with WGA provides sufficient nucleic acids for detection of viruses, bacteria, protozoa, and antibiotic resistance genes by the microarray in applications ranging from beach monitoring to risk assessment.

Exploitation of Nanotechnology for the Monitoring of Waterborne Pathogens: State-of-the-Art and Future Research Priorities

Contaminated drinking water is one of the most important environmental contributors to the human disease burden. Monitoring of water for the presence of pathogens is an essential part of ensuring drinking water safety. In order to assess water quality it is essential to have methods available to sample and detect the type, level and viability of pathogens in water which are effective, cheap, quick, sensitive, and where possible high throughput. Nanotechnology has the potential to drastically improve the monitoring of waterborne pathogens when compared to conventional approaches. To date, there have been no reviews that outline the applications of nanotechnology in this area despite increasing exploitation of nanotechnology for this purpose. This review is therefore the first overview of the state-of-the-art in the application of nanotechnology to waterborne pathogen sampling and detection schemes. Research in this field has been centered on the use of engineered nanomaterials. The effectiveness and limitations of nanomaterial-based approaches is outlined. A future outlook of the advances that are likely to emerge in this area, as well as recommendations for areas of further research are provided.

Waterborne pathogens: detection methods and challenges

Waterborne pathogens and related diseases are a major public health concern worldwide, not only by the morbidity and mortality that they cause, but by the high cost that represents their prevention and treatment. These diseases are directly related to environmental deterioration and pollution. Despite the continued efforts to maintain water safety, waterborne outbreaks are still reported globally. Proper assessment of pathogens on water and water quality monitoring are key factors for decision-making regarding water distribution systems’ infrastructure, the choice of best water treatment and prevention waterborne outbreaks. Powerful, sensitive and reproducible diagnostic tools are developed to monitor pathogen contamination in water and be able to detect not only cultivable pathogens but also to detect the occurrence of viable but non-culturable microorganisms as well as the presence of pathogens on biofilms. Quantitative microbial risk assessment (QMRA) is a helpful tool to evaluate the scenarios for pathogen contamination that involve surveillance, detection methods, analysis and decision-making. This review aims to present a research outlook on waterborne outbreaks that have occurred in recent years. This review also focuses in the main molecular techniques for detection of waterborne pathogens and the use of QMRA approach to protect public health.

Disability adjusted life year (DALY): a useful tool for quantitative assessment of environmental pollution

Disability adjusted life year (DALY) has been widely used since 1990s for evaluating global and/or regional burden of diseases. As many environmental pollutants are hazardous to human health, DALY is also recognized as an indicator to quantify the health impact of environmental pollution related to disease burden. Based on literature reviews, this article aims to give an overview of the applicable methodologies and research directions for using DALY as a tool for quantitative assessment of environmental pollution. With an introduction of the methodological framework of DALY, the requirements on data collection and manipulation for quantifying disease burdens are summarized. Regarding environmental pollutants hazardous to human beings, health effect/risk evaluation is indispensable for transforming pollution data into disease data through exposure and dose-response analyses which need careful selection of models and determination of parameters. Following the methodological discussions, real cases are analyzed with attention paid to chemical pollutants and pathogens usually encountered in environmental pollution. It can be seen from existing studies that DALY is advantageous over conventional environmental impact assessment for quantification and comparison of the risks resulted from environmental pollution. However, further studies are still required to standardize the methods of health effect evaluation regarding varied pollutants under varied circumstances before DALY calculation.

On the track for an efficient detection of Escherichia coli in water: A review on PCR-based methods

Ensuring water safety is an ongoing challenge to public health providers. Assessing the presence of fecal contamination indicators in water is essential to protect public health from diseases caused by waterborne pathogens. For this purpose, the bacteria Escherichia coli has been used as the most reliable indicator of fecal contamination in water. The methods currently in use for monitoring the microbiological safety of water are based on culturing the microorganisms. However, these methods are not the desirable solution to prevent outbreaks as they provide the results with a considerable delay, lacking on specificity and sensitivity. Moreover, viable but non-culturable microorganisms, which may be present as a result of environmental stress or water treatment processes, are not detected by culture-based methods and, thus, may result in false-negative assessments of E. coli in water samples. These limitations may place public health at significant risk, leading to substantial monetary losses in health care and, additionally, in costs related with a reduced productivity in the area affected by the outbreak, and in costs supported by the water quality control departments involved. Molecular methods, particularly polymerase chain reaction-based methods, have been studied as an alternative technology to overcome the current limitations, as they offer the possibility to reduce the assay time, to improve the detection sensitivity and specificity, and to identify multiple targets and pathogens, including new or emerging strains. The variety of techniques and applications available for PCR-based methods has increased considerably and the costs involved have been substantially reduced, which together have contributed to the potential standardization of these techniques. However, they still require further refinement in order to be standardized and applied to the variety of environmental waters and their specific characteristics. The PCR-based methods under development for monitoring the presence of E. coli in water are here discussed. Special emphasis is given to methodologies that avoid pre-enrichment during the water sample preparation process so that the assay time is reduced and the required legislated sensitivity is achieved. The advantages and limitations of these methods are also reviewed, contributing to a more comprehensive overview toward a more conscious research in identifying E. coli in water.

Sediment composition influences spatial variation in the abundance of human pathogen indicator bacteria within an estuarine environment

Faecal contamination of estuarine and coastal waters can pose a risk to human health, particularly in areas used for shellfish production or recreation. Routine microbiological water quality testing highlights areas of faecal indicator bacteria (FIB) contamination within the water column, but fails to consider the abundance of FIB in sediments, which under certain hydrodynamic conditions can become resuspended. Sediments can enhance the survival of FIB in estuarine environments, but the influence of sediment composition on the ecology and abundance of FIB is poorly understood. To determine the relationship between sediment composition (grain size and organic matter) and the abundance of pathogen indicator bacteria (PIB), sediments were collected from four transverse transects of the Conwy estuary, UK. The abundance of culturable Escherichia coli, total coliforms, enterococci, Campylobacter, Salmonella and Vibrio spp. in sediments was determined in relation to sediment grain size, organic matter content, salinity, depth and temperature. Sediments that contained higher proportions of silt and/or clay and associated organic matter content showed significant positive correlations with the abundance of PIB. Furthermore, the abundance of each bacterial group was positively correlated with the presence of all other groups enumerated. Campylobacter spp. were not isolated from estuarine sediments. Comparisons of the number of culturable E. coli, total coliforms and Vibrio spp. in sediments and the water column revealed that their abundance was 281, 433 and 58-fold greater in sediments (colony forming units (CFU)/100g) when compared with the water column (CFU/100ml), respectively. These data provide important insights into sediment compositions that promote the abundance of PIB in estuarine environments, with important implications for the modelling and prediction of public health risk based on sediment resuspension and transport.

Application of microfluidics in waterborne pathogen monitoring: a review

A review of the recent advances in microfluidics based systems for the monitoring of waterborne pathogens is provided in this article. Emphasis has been made on existing, commercial and state-of-the-art systems and research activities in laboratories worldwide. The review separates sample processing systems and monitoring systems, highlighting the slow progress made in automated sample processing for monitoring of pathogens in waterworks and in the field. Future potential directions of research are also highlighted in the conclusions.

3M™ Molecular detection system versus MALDI-TOF mass spectrometry and molecular techniques for the identification of Escherichia coli 0157:H7, Salmonella spp. &Listeria spp

The aim of this study was to compare standard selective plating, conventional PCR (16S rRNA and species specific primers), MALDI-TOF MS and the 3M™ Molecular Detection System for the routine detection of the pathogens Listeria, Salmonella and Escherichia coli 0157:H7 in wastewater and river water samples. MALDI-TOF MS was able to positively identify 20/21 (95%) of the E. coli isolates obtained at genus and species level, while 16S rRNA sequencing only correctly identified 6/21 (28%) as E. coli strains. None of the presumptive positive Listeria spp. and Salmonella spp. isolates obtained by culturing on selective media were positively identified by MALDI-TOF and 16S rRNA analysis. The species-specific E. coli 0157:H7 PCR described in this present study, was not able to detect any E. coli 0157:H7 strains in the wastewater and river water samples analysed. However, E. coli strains, Listeria spp., L. monocytogenes and Salmonella spp. were detected using species specific PCR. Escherichia coli 0157:H7, Listeria spp. and Salmonella spp. were also sporadically detected throughout the sampling period in the wastewater and river water samples analysed by the 3M™ Molecular Detection System. MALDI-TOF MS, which is a simple, accurate and cost-effective detection method, efficiently identified the culturable organisms, while in the current study both species specific PCR (Listeria spp. and Salmonella spp.) and 3M™ Molecular Detection System could be utilised for the direct routine analysis of pathogens in water sources.

Potential human pathogenic bacteria in a mixed urban watershed as revealed by pyrosequencing

Current microbial source tracking (MST) methods for water depend on testing for fecal indicator bacterial counts or specific marker gene sequences to identify fecal contamination where potential human pathogenic bacteria could be present. In this study, we applied 454 high-throughput pyrosequencing to identify bacterial pathogen DNA sequences, including those not traditionally monitored by MST and correlated their abundances to specific sources of contamination such as urban runoff and agricultural runoff from concentrated animal feeding operations (CAFOs), recreation park area, waste-water treatment plants, and natural sites with little or no human activities. Samples for pyrosequencing were surface water, and sediment collected from 19 sites. A total of 12,959 16S rRNA gene sequences with average length of ≤400 bp were obtained, and were assigned to corresponding taxonomic ranks using ribosomal database project (RDP), Classifier and Greengenes databases. The percent of total potential pathogens were highest in urban runoff water (7.94%), agricultural runoff sediment (6.52%), and Prado Park sediment (6.00%), respectively. Although the numbers of DNA sequence tags from pyrosequencing were very high for the natural site, corresponding percent potential pathogens were very low (3.78–4.08%). Most of the potential pathogenic bacterial sequences identified were from three major phyla, namely, Proteobacteria, Bacteroidetes, and Firmicutes. The use of deep sequencing may provide improved and faster methods for the identification of pathogen sources in most watersheds so that better risk assessment methods may be developed to enhance public health.

Recommendations following a multi-laboratory comparison of microbial source tracking methods

Microbial source tracking (MST) methods were evaluated in the Source Identification Protocol Project (SIPP), in which 27 laboratories compared methods to identify host sources of fecal pollution from blinded water samples containing either one or two different fecal types collected from California. This paper details lessons learned from the SIPP study and makes recommendations to further advance the field of MST. Overall, results from the SIPP study demonstrated that methods are available that can correctly identify whether particular host sources including humans, cows and birds have contributed to contamination in a body of water. However, differences between laboratory protocols and data processing affected results and complicated interpretation of MST method performance in some cases. This was an issue particularly for samples that tested positive (non-zero Ct values) but below the limits of quantification or detection of a PCR assay. Although false positives were observed, such samples in the SIPP study often contained the fecal pollution source that was being targeted, i.e., the samples were true positives. Given these results, and the fact that MST often requires detection of targets present in low concentrations, we propose that such samples be reported and identified in a unique category to facilitate data analysis and method comparisons. Important data can be lost when such samples are simply reported as positive or negative. Actionable thresholds were not derived in the SIPP study due to limitations that included geographic scope, age of samples, and difficulties interpreting low concentrations of target in environmental samples. Nevertheless, the results of the study support the use of MST for water management, especially to prioritize impaired waters in need of remediation. Future integration of MST data into quantitative microbial risk assessments and other models could allow managers to more efficiently protect public health based on site conditions.

Human impact on the microbiological water quality of the rivers

Microbiological contamination is an important water-quality problem worldwide. Human impact on this category of contamination is significant and several human-related activities, and also the population explosion, have affected and are still affecting dramatically the aquatic environment. Extensive industrialization and agriculture have led to increased pollution and hydromorphological changes in many river basins. The Danube river is one of the most affected by these changes where human involvement is undeniable, and subsequently, the Danube Delta Biosphere Reserve became one of the most vulnerable ecosystems. This review is an attempt to analyse the microbiological contamination and to identify the major role human activities play in altering the water quality of the rivers.

Evaluation of concentration efficiency of the Pseudomonas aeruginosa phage PP7 in various water matrixes by different methods

Enteric viruses monitoring in surface waters requires the concentration of viruses before detection assays. The aim of this study was to evaluate different methods in terms of recovery efficiencies of bacteriophage PP7 of Pseudomonas aeruginosa, measured by real-time PCR, using it as a viral control process in water analysis. Different nucleic acid extraction methods (silica-guanidinium thiocyanate, a commercial kit (Qiagen Viral RNA Kit) and phenol-chloroform with alcohol precipitation) exhibited very low recovery efficiencies (0.08-4.18 %), being the most efficient the commercial kit used for subsequent experiments. To evaluate the efficiency of three concentration methods, PBS (as model for clean water) and water samples from rivers were seeded to reach high (HC, 10(6) pfu ml(-1)) and low concentrations (LC, 10(4) pfu ml(-1)) of PP7. Tangential ultrafiltration proved to be more efficient (50.36 ± 12.91, 17.21 ± 9.22 and 12.58 ± 2.35 % for HC in PBS and two river samples, respectively) than adsorption-elution with negatively charged membranes (1.00 ± 1.34, 2.79 ± 2.62 and 0.05 ± 0.08 % for HC in PBS and two river samples, respectively) and polyethylene glycol precipitation (15.95 ± 7.43, 4.01 ± 1.12 and 3.91 ± 0.54 %, for HC in PBS and two river samples, respectively), being 3.2-50.4 times more efficient than the others for PBS and 2.7-252 times for river samples. Efficiencies also depended on the initial virus concentration and aqueous matrixes composition. In consequence, the incorporation of an internal standard like PP7 along the process is useful as a control of the water concentration procedure, the nucleic acid extraction, the presence of inhibitors and the variability of the recovery among replicas, and for the calculation of the sample limit of detection. Thus, the use of a process control, as presented here, is crucial for the accurate quantification of viral contamination.

Compatible immuno-NASBA LOC device for quantitative detection of waterborne pathogens: design and validation

Waterborne pathogens usually pose a global threat to animals and human beings. There has been a growing demand for convenient and sensitive tools to detect the potential emerging pathogens in water. In this study, a lab-on-a-chip (LOC) device based on the real-time immuno-NASBA (immuno-nucleic acid sequence-based amplification) assay was designed, fabricated and verified. The disposable immuno-NASBA chip is modelled on a 96-well ELISA microplate, which contains 43 reaction chambers inside the bionic channel networks. All valves are designed outside the chip and are reusable. The sample and reagent solutions were pushed into each chamber in turn, which was controlled by the valve system. Notably, the immuno-NASBA chip is completely compatible with common microplate readers in a biological laboratory, and can distinguish multiple waterborne pathogens in water samples quantitatively and simultaneously. The performance of the LOC device was demonstrated by detecting the presence of a synthetic peptide, ACTH (adrenocorticotropic hormone) and two common waterborne pathogens, Escherichia coli (E. coli) and rotavirus, in artificial samples. The results indicated that the LOC device has the potential to quantify traces of waterborne pathogens at femtomolar levels with high specificity, although the detection process was still subject to some factors, such as ribonuclease (RNase) contamination and non-specific adsorption. As an ultra-sensitive tool to quantify waterborne pathogens, the LOC device can be used to monitor water quality in the drinking water system. Furthermore, a series of compatible high-throughput LOC devices for monitoring waterborne pathogens could be derived from this prototype with the same design idea, which may render the complicated immuno-NASBA assays convenient to common users without special training.

Phenylboronic acid functionalized gold nanoparticles for highly sensitive detection of Staphylococcus aureus

Herein, we report a phenylboronic acid functionalized gold nanoparticle (GNP)-based colorimetric assay for rapid detection of Staphylococcus aureus (S. aureus) with high sensitivity. In this approach, GNPs can bind to S. aureus by the reaction of phenylboronic acid with the cis-diol configuration in glycans on the bacterial surface, providing a colorimetric readout of the binding event. Using this strategy, we have been able to quantify S. aureus at a concentration of 50 cells per mL (three times the standard deviation divided by the slope of the working curve) in aqueous solution.

Abundance of Enterococcus species, Enterococcus faecalis and Enterococcus faecium, essential indicators of fecal pollution, in river water

Enterococci such as Enterococcus faecalis and E. faecium are considered as the most suitable indicators of fecal pollution in an aquatic environment, and new methods for Enterococcus determination have been developed, namely, membrane filtration (MF) using membrane-Enterococcus indoxyl-β-D-glucoside agar (mEI) and defined substrate technology (DST) using Enterolert®. This study used PCR analysis to identify E. faecalis and E. faecium among Enterococcus strains in river water isolated using both mEI plates and Enterolert® trays. There was a significantly high correlation between MF and DST in terms of enterococcal counts for river water samples. The combined percentages of E. faecalis and E. faecium with respect to the total number of all strains obtained using mEI plates and Enterolert® trays were approximately 30 % and >30 %, respectively. Other than E. faecalis and E. faecium, a large number of Enterococcus species were unspecified in the actual urban river samples. A comparison of the predominance of E. faecalis and E. faecium found that the abundance of a species depended on the sampling river and date. E. faecium is a non-predominant species in intestinal and fecal Enterococci, and it was one of the main Enterococcus species detected in surface water.