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A special issue of Pathogens (ISSN 2076-0817). This special issue belongs to the section "Waterborne/Foodborne/Airborne Pathogens".

Deadline for manuscript submissions: closed (15 April 2015) | Viewed by 119290

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Special Issue Editor

Dr. Mark W. LeChevallier

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Guest Editor

Innovation & Environmental Stewardship, American Water, 1025 Laurel Oak Rd., P.O. Box 1770, Voorhees, NJ 08043, USA

Special Issue Information

Dear Colleagues,

Although the rates of waterborne disease in developed countries have declined over the past century, waterborne pathogens still represent important threats to public health in both developed and developing countries. Moreover, the nature of waterborne disease is changing from fecal-oral threats to include respiratory, dermal, and toxigenic effects. Pathogens that grow in biofilms and in premise plumbing are emerging as significant threats to public health. Free living amoebae are important both as opportunistic pathogens and hosts for amoebae-associated pathogens.

Protozoan pathogens including Giardia and Cryptosporidium continue to be of concern for water utility operators and regulators alike, primarily due to their environmental persistence and challenge to treatment barriers. Viruses are a challenge to both surface water and groundwater systems, but can also intrude into distribution system networks through main breaks and other low pressure events. Quantitative microbial risk assessments are increasingly being used not only to evaluate treatment efficacy, but also to help guide water utility operators to develop best practices. For this Special Issue of the journal Pathogens, we invite you to submit research papers and review articles relating to the broad spectrum of waterborne pathogens and waterborne disease. Papers on pathogen methods, occurrence, treatment and risk assessment are welcome. We are looking forward to publishing your state of the art research results and reviews.

Dr. Mark W. LeChevallier
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Pathogens is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

giardia
cryptosporidium
enteric viruses
free living amoeba
naegleria
enteric bacteria
legionella
non-tuberculous mycobacteria
cyanobacteria toxins
pathogen detection methods
quantitative microbial risk assessment

Published Papers (12 papers)

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Research

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259 KiB

Open AccessArticle

Enumeration of Somatic and F-RNA Phages as an Indicator of Fecal Contamination in Potable Water from Rural Areas of the North West Province

by Keitumetse Idah Nkwe, Collins Njie Ateba, Nomathamsanqa Patricia Sithebe and Cornelius Carlos Bezuidenhout

Pathogens 2015, 4(3), 503-512; https://doi.org/10.3390/pathogens4030503 - 01 Jul 2015

Cited by 4 | Viewed by 4949

Abstract

Bacteriophages are regarded as enteric viral indicators in faecally contaminated water systems and may indicate the presence of human viral pollution. They are relatively resistant to inactivation by natural and treatment processes. In this study, the presence of somatic coliphages and F-RNA coliphages was investigated in potable water from rural areas in the North West province. Water samples were aseptically collected from boreholes and tap water from some rural communities in the North West Province. Physical parameters of the water, such as the temperature, pH and turbidity, were measured before sample collection. Double-agar layer assay was performed using ISO, (1995, 2000) standard methods. Bottled water was used as a negative control and the strains фX174 and MS2 as positive controls. Of the 16 water samples collected, 15 were positive for somatic bacteriophages while F-RNA coliphages were detected in only two samples. Amongst the positive samples 189 and three plaque forming units were obtained for both somatic and F-RNA coliphages, respectively. No coliphage was detected in water from Masamane tap 1. The rest of the samples obtained from various rural areas were positive and did not comply with national and international standards for potable water. This was a cause for concern and should be further investigated. Full article

(This article belongs to the Special Issue Waterborne Pathogens)

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932 KiB

Open AccessArticle

Relationship between Organic Carbon and Opportunistic Pathogens in Simulated Glass Water Heaters

by Krista Williams, Amy Pruden, Joseph O. Falkinham III and Marc Edwards

Pathogens 2015, 4(2), 355-372; https://doi.org/10.3390/pathogens4020355 - 09 Jun 2015

Cited by 30 | Viewed by 6871

Abstract

Controlling organic carbon levels in municipal water has been hypothesized to limit downstream growth of bacteria and opportunistic pathogens in premise plumbing (OPPPs). Here, the relationships between influent organic carbon (0–15,000 µg ozonated fulvic acid /L) and the number of total bacteria [16S rRNA genes and heterotrophic plate counts (HPCs)] and a wide range of OPPPs (gene copy numbers of Acanthamoeba polyphaga, Vermamoeba vermiformis, Legionella pneumophila, and Mycobacterium avium) were examined in the bulk water of 120-mL simulated glass water heaters (SGWHs). The SGWHs were operated at 32–37 °C, which is representative of conditions encountered at the bottom of electric water heaters, with water changes of 80% three times per week to simulate low use. This design presented advantages of controlled and replicated (triplicate) conditions and avoided other potential limitations to OPPP growth in order to isolate the variable of organic carbon. Over seventeen months, strong correlations were observed between total organic carbon (TOC) and both 16S rRNA gene copy numbers and HPC counts (avg. R² > 0.89). Although M. avium gene copies were occasionally correlated with TOC (avg. R² = 0.82 to 0.97, for 2 out of 4 time points) and over a limited TOC range (0–1000 µg/L), no other correlations were identified between other OPPPs and added TOC. These results suggest that reducing organic carbon in distributed water is not adequate as a sole strategy for controlling OPPPs, although it may have promise in conjunction with other approaches. Full article

(This article belongs to the Special Issue Waterborne Pathogens)

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276 KiB

Open AccessArticle

Development of a Nucleic Acid Extraction Procedure for Simultaneous Recovery of DNA and RNA from Diverse Microbes in Water

by Vincent R. Hill, Jothikumar Narayanan, Rachel R. Gallen, Karen L. Ferdinand, Theresa Cromeans and Jan Vinjé

Pathogens 2015, 4(2), 335-354; https://doi.org/10.3390/pathogens4020335 - 26 May 2015

Cited by 32 | Viewed by 8630

Abstract

Drinking and environmental water samples contain a diverse array of constituents that can interfere with molecular testing techniques, especially when large volumes of water are concentrated to the small volumes needed for effective molecular analysis. In this study, a suite of enteric viruses, bacteria, and protozoan parasites were seeded into concentrated source water and finished drinking water samples, in order to investigate the relative performance of nucleic acid extraction techniques for molecular testing. Real-time PCR and reverse transcription-PCR crossing threshold (CT) values were used as the metrics for evaluating relative performance. Experimental results were used to develop a guanidinium isothiocyanate-based lysis buffer (UNEX buffer) that enabled effective simultaneous extraction and recovery of DNA and RNA from the suite of study microbes. Procedures for bead beating, nucleic acid purification, and PCR facilitation were also developed and integrated in the protocol. The final lysis buffer and sample preparation procedure was found to be effective for a panel of drinking water and source water concentrates when compared to commercial nucleic acid extraction kits. The UNEX buffer-based extraction protocol enabled PCR detection of six study microbes, in 100 L finished water samples from four drinking water treatment facilities, within three CT values (i.e., within 90% difference) of the reagent-grade water control. The results from this study indicate that this newly formulated lysis buffer and sample preparation procedure can be useful for standardized molecular testing of drinking and environmental waters. Full article

(This article belongs to the Special Issue Waterborne Pathogens)

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313 KiB

Open AccessArticle

Impact of Environmental Factors on Legionella Populations in Drinking Water

by David Otto Schwake, Absar Alum and Morteza Abbaszadegan

Pathogens 2015, 4(2), 269-282; https://doi.org/10.3390/pathogens4020269 - 19 May 2015

Cited by 21 | Viewed by 6195

Abstract

To examine the impact of environmental factors on Legionella in drinking water distribution systems, the growth and survival of Legionella under various conditions was studied. When incubated in tap water at 4 °C, 25 °C, and 32 °C, L. pneumophila survival trends varied amongst the temperatures, with the stable populations maintained for months at 25 °C and 32 °C demonstrating that survival is possible at these temperatures for extended periods in oligotrophic conditions. After inoculating coupons of PVC, copper, brass, and cast iron, L. pneumophila colonized biofilms formed on each within days to a similar extent, with the exception of cast iron, which contained 1-log less Legionella after 90 days. L. pneumophila spiked in a model drinking water distribution system colonized the system within days. Chlorination of the system had a greater effect on biofilm-associated Legionella concentrations, with populations returning to pre-chlorination levels within six weeks. Biofilms sampled from drinking water meters collected from two areas within central Arizona were analyzed via PCR for the presence of Legionella. Occurrence in only one area indicates that environmental differences in water distribution systems may have an impact on the survival of Legionella. These results document the impact of different environmental conditions on the survival of Legionella in water. Full article

(This article belongs to the Special Issue Waterborne Pathogens)

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882 KiB

Open AccessArticle

Global Occurrence and Emission of Rotaviruses to Surface Waters

by Nicholas M. Kiulia, Nynke Hofstra, Lucie C. Vermeulen, Maureen A. Obara, Gertjan Medema and Joan B. Rose

Pathogens 2015, 4(2), 229-255; https://doi.org/10.3390/pathogens4020229 - 13 May 2015

Cited by 56 | Viewed by 13716 | Correction

Abstract

Group A rotaviruses (RV) are the major cause of acute gastroenteritis in infants and young children globally. Waterborne transmission of RV and the presence of RV in water sources are of major public health importance. In this paper, we present the Global Waterborne Pathogen model for RV (GloWPa-Rota model) to estimate the global distribution of RV emissions to surface water. To our knowledge, this is the first model to do so. We review the literature to estimate three RV specific variables for the model: incidence, excretion rate and removal during wastewater treatment. We estimate total global RV emissions to be 2 × 10¹⁸ viral particles/grid/year, of which 87% is produced by the urban population. Hotspot regions with high RV emissions are urban areas in densely populated parts of the world, such as Bangladesh and Nigeria, while low emissions are found in rural areas in North Russia and the Australian desert. Even for industrialized regions with high population density and without tertiary treatment, such as the UK, substantial emissions are estimated. Modeling exercises like the one presented in this paper provide unique opportunities to further study these emissions to surface water, their sources and scenarios for improved management. Full article

(This article belongs to the Special Issue Waterborne Pathogens)

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Review

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479 KiB

Open AccessReview

HACCP-Based Programs for Preventing Disease and Injury from Premise Plumbing: A Building Consensus

by William F. McCoy and Aaron A. Rosenblatt

Pathogens 2015, 4(3), 513-528; https://doi.org/10.3390/pathogens4030513 - 09 Jul 2015

Cited by 14 | Viewed by 10431

Abstract

Thousands of preventable injuries and deaths are annually caused by microbial, chemical and physical hazards from building water systems. Water is processed in buildings before use; this can degrade the quality of the water. Processing steps undertaken on-site in buildings often include conditioning, filtering, storing, heating, cooling, pressure regulation and distribution through fixtures that restrict flow and temperature. Therefore, prevention of disease and injury requires process management. A process management framework for buildings is the hazard analysis and critical control point (HACCP) adaptation of failure mode effects analysis (FMEA). It has been proven effective for building water system management. Validation is proof that hazards have been controlled under operating conditions and may include many kinds of evidence including cultures of building water samples to detect and enumerate potentially pathogenic microorganisms. However, results from culture tests are often inappropriately used because the accuracy and precision are not sufficient to support specifications for control limit or action triggers. A reliable negative screen is based on genus-level Polymerase Chain Reaction (PCR) for Legionella in building water systems; however, building water samples with positive results from this test require further analysis by culture methods. Full article

(This article belongs to the Special Issue Waterborne Pathogens)

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892 KiB

Open AccessReview

Occurrence and Control of Legionella in Recycled Water Systems

by Patrick K. Jjemba, William Johnson, Zia Bukhari and Mark W. LeChevallier

Pathogens 2015, 4(3), 470-502; https://doi.org/10.3390/pathogens4030470 - 01 Jul 2015

Cited by 31 | Viewed by 9092

Abstract

Legionella pneumophila is on the United States Environmental Protection Agency (USEPA) Candidate Contaminant list (CCL) as an important pathogen. It is commonly encountered in recycled water and is typically associated with amoeba, notably Naegleria fowleri (also on the CCL) and Acanthamoeba sp. No legionellosis outbreak has been linked to recycled water and it is important for the industry to proactively keep things that way. A review was conducted examine the occurrence of Legionella and its protozoa symbionts in recycled water with the aim of developing a risk management strategy. The review considered the intricate ecological relationships between Legionella and protozoa, methods for detecting both symbionts, and the efficacy of various disinfectants. Full article

(This article belongs to the Special Issue Waterborne Pathogens)

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207 KiB

Open AccessReview

Environmental (Saprozoic) Pathogens of Engineered Water Systems: Understanding Their Ecology for Risk Assessment and Management

by Nicholas J. Ashbolt

Pathogens 2015, 4(2), 390-405; https://doi.org/10.3390/pathogens4020390 - 19 Jun 2015

Cited by 91 | Viewed by 9530

Abstract

Major waterborne (enteric) pathogens are relatively well understood and treatment controls are effective when well managed. However, water-based, saprozoic pathogens that grow within engineered water systems (primarily within biofilms/sediments) cannot be controlled by water treatment alone prior to entry into water distribution and other engineered water systems. Growth within biofilms or as in the case of Legionella pneumophila, primarily within free-living protozoa feeding on biofilms, results from competitive advantage. Meaning, to understand how to manage water-based pathogen diseases (a sub-set of saprozoses) we need to understand the microbial ecology of biofilms; with key factors including biofilm bacterial diversity that influence amoebae hosts and members antagonistic to water-based pathogens, along with impacts from biofilm substratum, water temperature, flow conditions and disinfectant residual—all control variables. Major saprozoic pathogens covering viruses, bacteria, fungi and free-living protozoa are listed, yet today most of the recognized health burden from drinking waters is driven by legionellae, non-tuberculous mycobacteria (NTM) and, to a lesser extent, Pseudomonas aeruginosa. In developing best management practices for engineered water systems based on hazard analysis critical control point (HACCP) or water safety plan (WSP) approaches, multi-factor control strategies, based on quantitative microbial risk assessments need to be developed, to reduce disease from largely opportunistic, water-based pathogens. Full article

(This article belongs to the Special Issue Waterborne Pathogens)

193 KiB

Open AccessReview

Opportunistic Premise Plumbing Pathogens: Increasingly Important Pathogens in Drinking Water

by Joseph O. Falkinham III, Amy Pruden and Marc Edwards

Pathogens 2015, 4(2), 373-386; https://doi.org/10.3390/pathogens4020373 - 09 Jun 2015

Cited by 177 | Viewed by 12823

Abstract

Opportunistic premise plumbing pathogens are responsible for a significant number of infections whose origin has been traced to drinking water. These opportunistic pathogens represent an emerging water borne disease problem with a major economic cost of at least $1 billion annually. The common features of this group of waterborne pathogens include: disinfectant-resistance, pipe surface adherence and biofilm formation, growth in amoebae, growth on low organic concentrations, and growth at low oxygen levels. Their emergence is due to the fact that conditions resulting from drinking water treatment select for them. As such, there is a need for novel approaches to reduce exposure to these pathogens. In addition to much-needed research, controls to reduce numbers and human exposure can be instituted independently by utilities and homeowners and hospital- and building-operators. Full article

(This article belongs to the Special Issue Waterborne Pathogens)

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Open AccessReview

Waterborne Pathogens: Detection Methods and Challenges

by Flor Yazmín Ramírez-Castillo, Abraham Loera-Muro, Mario Jacques, Philippe Garneau, Francisco Javier Avelar-González, Josée Harel and Alma Lilián Guerrero-Barrera

Pathogens 2015, 4(2), 307-334; https://doi.org/10.3390/pathogens4020307 - 21 May 2015

Cited by 336 | Viewed by 23718

Abstract

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. Full article

(This article belongs to the Special Issue Waterborne Pathogens)

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2194 KiB

Open AccessReview

Aichi Virus 1: Environmental Occurrence and Behavior

by Masaaki Kitajima and Charles P. Gerba

Pathogens 2015, 4(2), 256-268; https://doi.org/10.3390/pathogens4020256 - 19 May 2015

Cited by 66 | Viewed by 8967

Abstract

Aichi virus 1 (AiV-1), belonging to the genus Kobuvirus in the family Picornaviridae, has been proposed as a causative agent of human gastroenteritis potentially transmitted by fecal-oral routes through contaminated food or water. AiV-1 is globally distributed and has been detected in various types of environmental samples, such as sewage, river water, groundwater, and shellfish. Recent environmental studies revealed that this virus could be detected in higher frequency and greater abundance than other human enteric viruses. These findings suggest that AiV-1 could potentially be an appropriate indicator of viral contamination in the environment because of its high prevalence in water environments as well as structural and genetic similarity with some of the other important enteric viruses. Further studies on the occurrence and fate of AiV-1 in environments, even in combination with clinical studies of many regions, are needed for a better understanding of their epidemiology, temporal and geographical distribution, environmental stability, and potential health risks to humans. Full article

(This article belongs to the Special Issue Waterborne Pathogens)

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