37 results on '"Leifels M"'
Search Results
2. Co-incidence of BA.1 and BA.2 at the start of Singapore's Omicron wave revealed by Community and University Campus wastewater surveillance
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Chua, F.J.D., Kim, S.Y., Hill, E., Cai, J.W., Lee, W.L., Gu, X., Afri Affandi, S.A., Kwok, W.C.G., Ng, W., Leifels, M., Armas, F., Chandra, F., Chen, H., Alm, E.J., Tay, M., Wong, C.C.J., Ng, L.C., Wuertz, S., and Thompson, J.R.
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- 2023
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3. Surveillance of SARS-CoV-2 in Wastewater at the Population Level: Insights into the Implementation of Non-invasive Targeted Monitoring in Singapore and the USA
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Leifels, M., primary, Lee, W. L., additional, Armas, F., additional, Gu, X., additional, Chandra, F., additional, Cheng, D., additional, Kwok, W. C., additional, Chua, D., additional, Kim, S. Y., additional, Ng, W. J., additional, Nainai, D., additional, Sirikanchana, K., additional, Sozzi, E., additional, Farnleitner, A. H., additional, Wu, F., additional, Wuertz, S., additional, and Thompson, J., additional
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- 2023
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4. Magnetic nanoparticles in toner material
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Getzlaff, M., Leifels, M., Weber, P., Kökcam-Demir, Ü., and Janiak, Ch.
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- 2020
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5. Nanoparticles in toner material
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Getzlaff, M., Leifels, M., Weber, P., Kökcam-Demir, Ü., and Janiak, Ch.
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- 2019
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6. Coexistence of free-living amoebae and bacteria in selected South African hospital water distribution systems
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Muchesa, P., Leifels, M., Jurzik, L., Hoorzook, K. B., Barnard, T. G., and Bartie, C.
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- 2017
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7. Global water, sanitation and hygiene research priorities and learning challenges under Sustainable Development Goal 6
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Setty, K, Jiménez, A, Willetts, J, Leifels, M, Bartram, J, Setty, K, Jiménez, A, Willetts, J, Leifels, M, and Bartram, J
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© The Authors 2019. Development Policy Review © 2019 Overseas Development Institute Motivation: Sanitation and Water for All (SWA) is a global partnership addressing universal water, sanitation and hygiene (WaSH) access. Shortly after the adoption of the Sustainable Development Goals (SDGs) by the United Nations, the research and learning (R&L) constituency of SWA undertook a systematic study to determine global research priorities and learning needs. Purpose: To identify priority topics where improved knowledge would aid achievement of Goal 6 by developing a global WaSH research agenda, and to describe evidence-use challenges among WaSH professionals. Approach and methods: We delivered a tailored, semi-structured electronic questionnaire to representatives from countries, R&L institutions, and other SWA partners (external support agencies, civil society, and private sector). The survey gathered views from 76 respondents working in an estimated 36 countries across all world regions. Data were analysed quantitatively and qualitatively to identify patterns and themes. Findings: Most responses indicated lower confidence in at least one Goal 6 target area, especially managing untreated wastewater and faecal sludge. To support learning, respondents valued a combination of both brief and lengthy information formats. WaSH information was perceived as contradictory or unreliable only among non-R&L constituencies. The R&L constituency saw ample learning and training opportunities, while others perceived barriers to participating. WaSH activities were frequently constrained by upward accountability to funders, while stakeholder inclusion was inconsistent. Policy implications: This study offers insight into perceived research and decision challenges related to Goal 6 targets. It develops a unified research agenda focused on high-priority topics, and recommends renewed attention to evidence synthesis, learning and implementation support, research engagement and multisectoral co
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- 2020
8. Global Water, Sanitation, and Hygiene Research Priorities and Learning Challenges under Sustainable Development Goal 6
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Setty, K, Jiménez, A, Willetts, J, Leifels, M, Bartram, J, Setty, K, Jiménez, A, Willetts, J, Leifels, M, and Bartram, J
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- 2018
9. Mikrobiologische Risikobewertung (QMRA) – eine Strategie zur Bewertung der mikrobiologischen Gewässerqualität
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Leifels, M, additional and Jurzik, L, additional
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- 2018
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10. Detection of amoeba-associatedLegionella pneumophilain hospital water networks of Johannesburg
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Muchesa, P, primary, Leifels, M, additional, Jurzik, L, additional, Barnard, TG, additional, and Bartie, C, additional
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- 2018
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11. Coexistence of free-living amoebae and bacteria in selected South African hospital water distribution systems
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Muchesa, P., primary, Leifels, M., additional, Jurzik, L., additional, Hoorzook, K. B., additional, Barnard, T. G., additional, and Bartie, C., additional
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- 2016
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12. Detection of amoeba-associated Legionella pneumophila in hospital water networks of Johannesburg.
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Muchesa, P, Leifels, M, Jurzik, L, Barnard, TG, and Bartie, C
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LEGIONELLA pneumophila ,AMOEBA ,WATER pollution - Abstract
The prevalence of free-living amoeba and associated Legionella spp. in hospital water systems may pose a risk of Legionnaires’ disease to immuno-compromised patients. This study investigated the occurrence of amoeba-associated Legionella pneumophila in three South African hospital water systems. A total of 98 water and/or biofilm samples were collected from the sterilisation unit, theatres, neonatal ward and intensive care units. Amoebae were isolated from 71 (72.4%) samples. Isolated amoebae were analysed using qPCR and culture methods to test for the presence of Legionella. L. pneumophila did not grow on selective media in any of the samples. A total of 7 out of the 71 (9.9%) amoeba-positive samples showed a positive reaction for L. pneumophila using qPCR. Although relatively few samples were positive for Legionella in this preliminary study, the association with amoeba still presents a potential public health risk to immuno-compromised patients when exposed to contaminated water. [ABSTRACT FROM AUTHOR]
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- 2018
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13. Free-living amoebae isolated from a hospital water system in South Africa: a potential source of nosocomial and occupational infection
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Muchesa, P., primary, Leifels, M., primary, Jurzik, L., primary, Barnard, T. G., primary, and Bartie, C., primary
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- 2015
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14. Detection of amoeba-associated Legionella pneumophilain hospital water networks of Johannesburg
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Muchesa, P, Leifels, M, Jurzik, L, Barnard, TG, and Bartie, C
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The prevalence of free-living amoeba and associated Legionellaspp. in hospital water systems may pose a risk of Legionnaires’ disease to immuno-compromised patients. This study investigated the occurrence of amoeba-associated Legionella pneumophilain three South African hospital water systems. A total of 98 water and/or biofilm samples were collected from the sterilisation unit, theatres, neonatal ward and intensive care units. Amoebae were isolated from 71 (72.4%) samples. Isolated amoebae were analysed using qPCR and culture methods to test for the presence of Legionella. L. pneumophiladid not grow on selective media in any of the samples. A total of 7 out of the 71 (9.9%) amoeba-positive samples showed a positive reaction for L. pneumophilausing qPCR.Although relatively few samples were positive for Legionellain this preliminary study, the association with amoeba still presents a potential public health risk to immuno-compromised patients when exposed to contaminated water.
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- 2018
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15. Free-living amoebae isolated from a hospital water system in South Africa: a potential source of nosocomial and occupational infection.
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Muchesa, P., Leifels, M., Jurzik, L., Barnard, T. G., and Bartie, C.
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BIOFILMS ,MICROBIAL aggregation ,WATER spirits ,WATER ,WATER quality - Abstract
This study investigated the occurrence of free-living amoebae (FLA) in a public hospital in South Africa. A total of 97 water and biofilm samples from the municipal water inlet of the hospital, theatres, theatre sterilization service unit, central sterilization service unit, endoscopy/gastroscopy unit, intensive care unit and the renal unit were collected and examined for the presence of FLA using an amoebal co-culture and molecular techniques. Of the 97 samples, 77 (79.4%), 40 (52%) water and 37 (48.1%) biofilm, contained FLA. The genera Acanthamoeba, Vermamoeba (formerly Hartmanella) and Naegleria were detected by morphology, 18S rRNA PCR (polymerase chain reaction) and sequence analyses. Further sequence analysis of the five Acanthamoeba-positive isolates revealed a close resemblance with the potentially pathogenic T20 genotype. These results show a potential health risk to immuno-compromised patients and health care workers as some of the species detected are pathogenic and may harbor potential intracellular bacteria responsible for nosocomial infections. To date, this is the first report on the detection of potentially pathogenic amoebae from South African hospital water systems. [ABSTRACT FROM AUTHOR]
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- 2016
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16. Tricks and tracks of prevalence, occurrences, treatment technologies, and challenges of mixtures of emerging contaminants in the environment: With special emphasis on microplastic.
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Sudarsan JS, Dogra K, Kumar R, Raval NP, Leifels M, Mukherjee S, Trivedi MH, Jain MS, Zang J, Barceló D, Mahlknecht J, and Kumar M
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- Humans, Environmental Pollutants analysis, Environmental Monitoring methods, Water Pollutants, Chemical analysis, Environmental Restoration and Remediation methods, Microplastics analysis
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This paper aims to emphasize the occurrence of various emerging contaminant (EC) mixtures in natural ecosystems and highlights the primary concern arising from the unregulated release into soil and water, along with their impacts on human health. Emerging contaminant mixtures, including pharmaceuticals, personal care products, dioxins, polychlorinated biphenyls, pesticides, antibiotics, biocides, surfactants, phthalates, enteric viruses, and microplastics (MPs), are considered toxic contaminants with grave implications. MPs play a crucial role in transporting pollutants to aquatic and terrestrial ecosystems as they interact with the various components of the soil and water environments. This review summarizes that major emerging contaminants (ECs), like trimethoprim, diclofenac, sulfamethoxazole, and 17α-Ethinylestradiol, pose serious threats to public health and contribute to antimicrobial resistance. In addressing human health concerns and remediation techniques, this review critically evaluates conventional methods for removing ECs from complex matrices. The diverse physiochemical properties of surrounding environments facilitate the partitioning of ECs into sediments and other organic phases, resulting in carcinogenic, teratogenic, and estrogenic effects through active catalytic interactions and mechanisms mediated by aryl hydrocarbon receptors. The proactive toxicity of ECs mixture complexation and, in part, the yet-to-be-identified environmental mixtures of ECs represent a blind spot in current literature, necessitating conceptual frameworks for assessing the toxicity and risks with individual components and mixtures. Lastly, this review concludes with an in-depth exploration of future scopes, knowledge gaps, and challenges, emphasizing the need for a concerted effort in managing ECs and other organic pollutants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)
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- 2024
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17. Domestic hot-water boilers harbour active thermophilic bacterial communities distinctly different from those in the cold-water supply.
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Egli T, Campostrini L, Leifels M, Füchslin HP, Kolm C, Dan C, Zimmermann S, Hauss V, Guiller A, Grasso L, Shajkofci A, Farnleitner AH, and Kirschner AKT
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- Humans, RNA, Ribosomal, 16S, Ecosystem, Water Supply, Bacteria genetics, Water Microbiology, Drinking Water microbiology, Legionella
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Running cold and hot water in buildings is a widely established commodity. However, interests regarding hygiene and microbiological aspects had so far been focussed on cold water. Little attention has been given to the microbiology of domestic hot-water installations (DHWIs), except for aspects of pathogenic Legionella. World-wide, regulations consider hot (or warm) water as 'heated drinking water' that must comply (cold) drinking water (DW) standards. However, the few reports that exist indicate presence and growth of microbial flora in DHWIs, even when supplied with water with disinfectant residual. Using flow cytometric (FCM) total cell counting (TCC), FCM-fingerprinting, and 16S rRNA-gene-based metagenomic analysis, the characteristics and composition of bacterial communities in cold drinking water (DW) and hot water from associated boilers (operating at 50 - 60 °C) was studied in 14 selected inhouse DW installations located in Switzerland and Austria. A sampling strategy was applied that ensured access to the bulk water phase of both, supplied cold DW and produced hot boiler water. Generally, 1.3- to 8-fold enhanced TCCs were recorded in hot water compared to those in the supplied cold DW. FCM-fingerprints of cold and corresponding hot water from individual buildings indicated different composition of cold- and hot-water microbial floras. Also, hot waters from each of the boilers sampled had its own individual FCM-fingerprint. 16S rRNA-gene-based metagenomic analysis confirmed the marked differences in composition of microbiomes. E.g., in three neighbouring houses supplied from the same public network pipe each hot-water boiler contained its own thermophilic bacterial flora. Generally, bacterial diversity in cold DW was broad, that in hot water was restricted, with mostly thermophilic strains from the families Hydrogenophilaceae, Nitrosomonadaceae and Thermaceae dominating. Batch growth assays, consisting of cold DW heated up to 50 - 60 °C and inoculated with hot water, resulted in immediate cell growth with doubling times between 5 and 10 h. When cold DW was used as an inoculum no significant growth was observed. Even boilers supplied with UVC-treated cold DW contained an actively growing microbial flora, suggesting such hot-water systems as autonomously operating, thermophilic bioreactors. The generation of assimilable organic carbon from dissolved organic carbon due to heating appears to be the driver for growth of thermophilic microbial communities. Our report suggests that a man-made microbial ecosystem, very close to us all and of potential hygienic importance, may have been overlooked so far. Despite consumers having been exposed to microbial hot-water flora for a long time, with no major pathogens so far been associated specifically with hot-water usage (except for Legionella), the role of harmless thermophiles and their interaction with potential human pathogens able to grow at elevated temperatures in DHWIs remains to be investigated., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Thomas Egli reports financial support, article publishing charges, and equipment, drugs, or supplies were provided by bNovate Technologies SA. Thomas Egli reports financial support, administrative support, and article publishing charges were provided by Microbes-in-Water GmbH. Thomas Egli reports a relationship with bNovate Technologies SA that includes: equity or stocks. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)
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- 2024
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18. Contextualizing Wastewater-Based surveillance in the COVID-19 vaccination era.
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Armas F, Chandra F, Lee WL, Gu X, Chen H, Xiao A, Leifels M, Wuertz S, Alm EJ, and Thompson J
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- Humans, Pandemics, SARS-CoV-2, Wastewater, Wastewater-Based Epidemiological Monitoring, Vaccination, COVID-19 Vaccines, COVID-19 prevention & control
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SARS-CoV-2 wastewater-based surveillance (WBS) offers a tool for cost-effective oversight of a population's infections. In the past two years, WBS has proven to be crucial for managing the pandemic across different geographical regions. However, the changing context of the pandemic due to high levels of COVID-19 vaccination warrants a closer examination of its implication towards SARS-CoV-2 WBS. Two main questions were raised: 1) Does vaccination cause shedding of viral signatures without infection? 2) Does vaccination affect the relationship between wastewater and clinical data? To answer, we review historical reports of shedding from viral vaccines in use prior to the COVID-19 pandemic including for polio, rotavirus, influenza and measles infection and provide a perspective on the implications of different COVID-19 vaccination strategies with regard to the potential shedding of viral signatures into the sewershed. Additionally, we reviewed studies that looked into the relationship between wastewater and clinical data and how vaccination campaigns could have affected the relationship. Finally, analyzing wastewater and clinical data from the Netherlands, we observed changes in the relationship concomitant with increasing vaccination coverage and switches in dominant variants of concern. First, that no vaccine-derived shedding is expected from the current commercial pipeline of COVID-19 vaccines that may confound interpretation of WBS data. Secondly, that breakthrough infections from vaccinated individuals contribute significantly to wastewater signals and must be interpreted in light of the changing dynamics of shedding from new variants of concern., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper: [Eric J Alm reports a relationship with Biobot Analytics, Inc. that includes: consulting or advisory and equity or stocks.]., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)
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- 2023
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19. Monitoring human arboviral diseases through wastewater surveillance: Challenges, progress and future opportunities.
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Lee WL, Gu X, Armas F, Leifels M, Wu F, Chandra F, Chua FJD, Syenina A, Chen H, Cheng D, Ooi EE, Wuertz S, Alm EJ, and Thompson J
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- Humans, Sewage, Wastewater, Wastewater-Based Epidemiological Monitoring, Arbovirus Infections diagnosis, Arbovirus Infections epidemiology, Arboviruses, COVID-19, Zika Virus, Zika Virus Infection diagnosis, Zika Virus Infection epidemiology
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Arboviral diseases are caused by a group of viruses spread by the bite of infected arthropods. Amongst these, dengue, Zika, west nile fever and yellow fever cause the greatest economic and social impact. Arboviral epidemics have increased in frequency, magnitude and geographical extent over the past decades and are expected to continue increasing with climate change and expanding urbanisation. Arboviral prevalence is largely underestimated, as most infections are asymptomatic, nevertheless existing surveillance systems are based on passive reporting of loosely defined clinical syndromes with infrequent laboratory confirmation. Wastewater-based surveillance (WBS), which has been demonstrated to be useful for monitoring diseases with significant asymptomatic populations including COVID19 and polio, could be a useful complement to arboviral surveillance. We review the current state of knowledge and identify key factors that affect the feasibility of monitoring arboviral diseases by WBS to include viral shedding loads by infected persons, the persistence of shed arboviruses and the efficiency of their recovery from sewage. We provide a simple model on the volume of wastewater that needs to be processed for detection of arboviruses, in face of lower arboviral shedding rates. In all, this review serves to reflect on the key challenges that need to be addressed and overcome for successful implementation of arboviral WBS., Competing Interests: Declaration of Competing Interest E.J.A. is advisor to Biobot Analytics, Inc. and holds shares in the company., (Copyright © 2022. Published by Elsevier Ltd.)
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- 2022
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20. Rapid displacement of SARS-CoV-2 variant Delta by Omicron revealed by allele-specific PCR in wastewater.
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Lee WL, Armas F, Guarneri F, Gu X, Formenti N, Wu F, Chandra F, Parisio G, Chen H, Xiao A, Romeo C, Scali F, Tonni M, Leifels M, Chua FJD, Kwok GW, Tay JY, Pasquali P, Thompson J, Alborali GL, and Alm EJ
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- Alleles, COVID-19 Testing, Humans, RNA, Viral, Real-Time Polymerase Chain Reaction, Wastewater analysis, COVID-19, SARS-CoV-2 genetics
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On November 26, 2021, the B.1.1.529 COVID-19 variant was classified as the Omicron variant of concern (VOC). Reports of higher transmissibility and potential immune evasion triggered flight bans and heightened health control measures across the world to stem its distribution. Wastewater-based surveillance has demonstrated to be a useful complement for clinical community-based tracking of SARS-CoV-2 variants. Using design principles of our previous assays that detect SARS-CoV-2 variants (Alpha and Delta), we developed an allele-specific RT-qPCR assay which simultaneously targets the stretch of mutations from Q493R to Q498R for quantitative detection of the Omicron variant in wastewater. We report their validation against 10-month longitudinal samples from the influent of a wastewater treatment plant in Italy. SARS-CoV-2 RNA concentrations and variant frequencies in wastewater determined using these variant assays agree with clinical cases, revealing rapid displacement of the Delta variant by the Omicron variant within three weeks. These variant trends, when mapped against vaccination rates, support clinical studies that found the rapid emergence of SARS-CoV-2 Omicron variant being associated with an infection advantage over Delta in vaccinated persons. These data reinforce the versatility, utility and accuracy of these open-sourced methods using allele-specific RT-qPCR for tracking the dynamics of variant displacement in communities through wastewater for informed public health responses., (Copyright © 2022. Published by Elsevier Ltd.)
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- 2022
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21. Making waves: Wastewater surveillance of SARS-CoV-2 in an endemic future.
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Wu F, Lee WL, Chen H, Gu X, Chandra F, Armas F, Xiao A, Leifels M, Rhode SF, Wuertz S, Thompson J, and Alm EJ
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- Humans, Pandemics, RNA, Viral, Wastewater, Wastewater-Based Epidemiological Monitoring, COVID-19 epidemiology, SARS-CoV-2
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Wastewater-based surveillance (WBS) has been widely used as a public health tool to monitor the emergence and spread of SARS-CoV-2 infections in populations during the COVID-19 pandemic. Coincident with the global vaccination efforts, the world is also enduring new waves of SARS-CoV-2 variants. Reinfections and vaccine breakthroughs suggest an endemic future where SARS-CoV-2 continues to persist in the general population. In this treatise, we aim to explore the future roles of wastewater surveillance. Practically, WBS serves as a relatively affordable and non-invasive tool for mass surveillance of SARS-CoV-2 infection while minimizing privacy concerns, attributes that make it extremely suited for its long-term usage. In an endemic future, the utility of WBS will include 1) monitoring the trend of viral loads of targets in wastewater for quantitative estimate of changes in disease incidence; 2) sampling upstream for pinpointing infections in neighborhoods and at the building level; 3) integrating wastewater and clinical surveillance for cost-efficient population surveillance; and 4) genome sequencing wastewater samples to track circulating and emerging variants in the population. We further discuss the challenges and future developments of WBS to reduce inconsistencies in wastewater data worldwide, improve its epidemiological inference, and advance viral tracking and discovery as a preparation for the next viral pandemic., (Copyright © 2022. Published by Elsevier Ltd.)
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- 2022
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22. The one health perspective to improve environmental surveillance of zoonotic viruses: lessons from COVID-19 and outlook beyond.
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Leifels M, Khalilur Rahman O, Sam IC, Cheng D, Chua FJD, Nainani D, Kim SY, Ng WJ, Kwok WC, Sirikanchana K, Wuertz S, Thompson J, and Chan YF
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The human population has doubled in the last 50 years from about 3.7 billion to approximately 7.8 billion. With this rapid expansion, more people live in close contact with wildlife, livestock, and pets, which in turn creates increasing opportunities for zoonotic diseases to pass between animals and people. At present an estimated 75% of all emerging virus-associated infectious diseases possess a zoonotic origin, and outbreaks of Zika, Ebola and COVID-19 in the past decade showed their huge disruptive potential on the global economy. Here, we describe how One Health inspired environmental surveillance campaigns have emerged as the preferred tools to monitor human-adjacent environments for known and yet to be discovered infectious diseases, and how they can complement classical clinical diagnostics. We highlight the importance of environmental factors concerning interactions between animals, pathogens and/or humans that drive the emergence of zoonoses, and the methodologies currently proposed to monitor them-the surveillance of wastewater, for example, was identified as one of the main tools to assess the spread of SARS-CoV-2 by public health professionals and policy makers during the COVID-19 pandemic. One-Health driven approaches that facilitate surveillance, thus harbour the potential of preparing humanity for future pandemics caused by aetiological agents with environmental reservoirs. Via the example of COVID-19 and other viral diseases, we propose that wastewater surveillance is a useful complement to clinical diagnosis as it is centralized, robust, cost-effective, and relatively easy to implement., Competing Interests: Competing interestsThe authors declare no competing interests., (© The Author(s) 2022.)
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- 2022
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23. Pathogen performance testing of a natural swimming pool using a cocktail of microbiological surrogates and QMRA-derived management goals.
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Shoults DC, Li Q, Petterson S, Rudko SP, Dlusskaya L, Leifels M, Scott C, Schlosser C, and Ashbolt NJ
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- Child, Goals, Humans, Risk Assessment, Water Microbiology, Cryptosporidiosis, Cryptosporidium, Swimming Pools
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In recent decades, natural swimming pools (NSPs) have gained popularity in Europe, especially in Germany and Austria. NSPs differ from swimming pools in that they utilize biological treatment processes based on wetland processes with no disinfection residual. However, data are missing on the specific log-reduction performance of NSPs to address enteric virus, bacteria, and parasitic protozoa removal considered necessary to meet the North American risk-based benchmark (<35 illnesses per 1,000 swimming events) set by the USEPA for voluntary swimming. In this study, we examined Canada's first NSP at Borden Park, Edmonton, Canada, to address the following three questions: (1) Given normal faecal shedding rates by bathers, what is the total log reduction (TLR) theoretically needed to meet the EPA benchmark? (2) what is the in-situ performance of the NSP based on spiking suitable microbial surrogates (MS2 coliphage, Enterococcus faecalis, and Saccharomyces cerevisiae [Baker's yeast])? and (3) how much time is required to reach acceptable bather risk levels under different representative volume-turnover rates? A reverse-quantitative microbial risk assessment (QMRA) revealed that of the four reference pathogens selected (Norovirus, Campylobacter, Cryptosporidium, and Giardia), only Norovirus was estimated to exceed the risk benchmark at the 50th, 75th, and 95th percentiles, while Campylobacter was the only other reference pathogen to exceed at the 95th percentile. Log-reduction values (LRVs) were similar to previous reports for bacterial indicators, and novel LRVs were estimated for the other two surrogates. A key finding was that more than 24 h treatment time would be necessary to provide acceptable bather protection following heavy bather use (378 bathers/day for main pool and 26 bathers/day for children's pool), due to the mixing dynamics of the treated water diluting out possible residual pool faecal contamination. The theoretical maximum number of people in the pool per day to be below USEPA's 35 gastro cases in 1,000 swimming events was 113, 47, and 8, at the 50th, 75th, and 95th percentiles. Further, the use of ultra-violet disinfection to the pool return flow had little effect on reducing the treatment time required.
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- 2021
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24. Mega festivals like MahaKumbh, a largest mass congregation, facilitated the transmission of SARS-CoV-2 to humans and endangered animals via contaminated water.
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Patel AK, Mukherjee S, Leifels M, Gautam R, Kaushik H, Sharma S, and Kumar O
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- Animals, Endangered Species, Humans, India, Water Microbiology, Water Pollution, COVID-19 transmission, Holidays, Rivers microbiology, SARS-CoV-2
- Abstract
Our surrounding environment has been influenced by the COVID-19 pandemic situation. The second wave of COVID-19 in India has proven to be more devastating and aggressive than the first wave of the pandemic, which led to recognizing India as one of the world's topmost worst-hit nations considering >4000 fatalities reported in a single day in May 2021. Such "resurgence and acceleration" of COVID-19 transmission has been fuelled by the MahaKumbh festival and political mass gathering (elections rallies) events, where the COVID-19 protocols have been ignored by millions of pilgrims/followers. The present review discusses only the consequences of this year's MahaKumbh festivals, the largest religious mass gathering on earth, which was held during the COVID-19 pandemic in India, and its impact on both the spread of SARS-CoV-2 among participants and their families and its influence on the quality of the river Ganga. This article tries to give readers outside of India an overview of how much impact of any such single large gathering of any relgion in any part of the world can drive coronavirus infections and effectively commence the second/third wave outbreak with this case study. Furthermore, the religious large scale celebration are widely accepted through out the world that have played a significant role in the spread of the pandemic into remote villages and towns all over the subcontinent/world, thus affecting many areas with insufficient healthcare facilities that have been relatively spared. This review also highlights the potential risk of transmission from infected humans into the aquatic environment of the river Ganga. Besides the obvious relevance of SARS-CoV-2, a large variety of other water-related disease vectors (bacteria, viruses, and protozoa) stemming from visitors to the religious congregation were introduced into the upstream regions of the Ganga river. Their sheer number is assumed to have had a severe influence on its delicate ecosystem, including endangered mammals such as the river Dolphins. The detailed epidemiological and clinical study on transmission routes of SARS-CoV-2 is the need of the hour to understand the pathogenesis of RNA virus infection and prevent the massive spreading of such infectious respiratory diseases. An interdisciplinary approach, rooted in evidence-based efficient learning, contextual strategies, and a streamlined unified approach should be adopted to help in the development of a proactive prevention model during future MahaKumbh festival (and similar religious gatherings) instead of just "picking up the pieces" in a conventional post-event model., (Copyright © 2021 Elsevier GmbH. All rights reserved.)
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- 2021
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25. Characteristics and Injury Patterns of Road Traffic Injuries in Urban and Rural Uganda-A Retrospective Medical Record Review Study in Two Hospitals.
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Temizel S, Wunderlich R, and Leifels M
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- Adult, Cross-Sectional Studies, Female, Hospitals, Humans, Male, Medical Records, Retrospective Studies, Uganda epidemiology, Accidents, Traffic, Wounds and Injuries epidemiology
- Abstract
In the ongoing Second Decade of Action for Road Safety, road traffic crashes pose a considerable threat especially in low-income countries. Uganda shows a vast burden of non-fatal injuries and resides at the top range of countries with the highest death rates due to unsafe roads. However, little is known about the differences in road traffic associated injuries between urban and rural areas and potential influence factors. Here, we used a cross-sectional study conducted by a retrospective medical record review from trauma cases admitted in 2016 to hospitals in rural and urban areas in Uganda. Injury severity scores were calculated and descriptive analysis was carried out while multivariate logistic regression was applied to assess significant covariates. According to the 1683 medical records reviewed, the mean age of trauma patients in the dataset under investigation was 30.8 years with 74% male. The trauma in-hospital mortality was 4% while prevalence of traumatic injuries is 56.4%. Motorcycle users (49.6%) and pedestrians (33.7%) were identified as the most vulnerable groups in both urban and rural setting while mild injuries of extremities (61.6%) and the head/neck-region (42.0%) were registered most. The frequency of road traffic injuries was homogenous in the urban and rural hospitals investigated in this study; interventions should therefore be intensified ubiquitously. The identification of significant differences in road traffic crash and injury characteristics provides the opportunity for specific programmes to decrease the socio-economic and health burden of unsafe roads. In addition to law enforcement and introduction of a Systems Thinking approach to road safety including infrastructural and educational concepts, the strengthening of trauma care and health resources is recommended.
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- 2021
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26. Capsid integrity quantitative PCR to determine virus infectivity in environmental and food applications - A systematic review.
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Leifels M, Cheng D, Sozzi E, Shoults DC, Wuertz S, Mongkolsuk S, and Sirikanchana K
- Abstract
Capsid integrity quantitative PCR (qPCR), a molecular detection method for infectious viruses combining azo dye pretreatment with qPCR, has been widely used in recent years; however, variations in pretreatment conditions for various virus types can limit the efficacy of specific protocols. By identifying and critically synthesizing forty-one recent peer-reviewed studies employing capsid integrity qPCR for viruses in the last decade (2009-2019) in the fields of food safety and environmental virology, we aimed to establish recommendations for the detection of infectious viruses. Intercalating dyes are effective measures of viability in PCR assays provided the viral capsid is damaged; viruses that have been inactivated by other causes, such as loss of attachment or genomic damage, are less well detected using this approach. Although optimizing specific protocols for each virus is recommended, we identify a framework for general assay conditions. These include concentrations of ethidium monoazide, propidium monoazide or its derivates between 10 and 200 μM; incubation on ice or at room temperature (20 - 25 °C) for 5-120 min; and dye activation using LED or high light (500-800 Watts) exposure for periods ranging from 5 to 20 min. These simple steps can benefit the investigation of infectious virus transmission in routine (water) monitoring settings and during viral outbreaks such as the current COVID-19 pandemic or endemic diseases like dengue fever., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2020 The Authors.)
- Published
- 2020
- Full Text
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27. Global Water, Sanitation and Hygiene Research Priorities and Learning Challenges under Sustainable Development Goal 6.
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Setty K, Jiménez A, Willetts J, Leifels M, and Bartram J
- Abstract
Motivation: Sanitation and Water for All (SWA) is a global partnership addressing challenges to universal water, sanitation, and hygiene (WaSH) access. Shortly following adoption of the United Nations' Sustainable Development Goals, the Research and Learning (R&L) constituency of SWA undertook a systematic study to determine global research priorities and learning needs., Purpose: We aimed to identify priority topics where improved knowledge would aid achievement of Goal 6, by developing a global WaSH research agenda, and to describe evidence-use challenges among WaSH professionals., Approach and Methods: We delivered a tailored, semi-structured electronic questionnaire to representatives from countries, R&L institutions, and other SWA partners (external support agencies, civil society, and private sector). The survey gathered views from 76 respondents working in an estimated 36 countries across all world regions. Data were analyzed quantitatively and qualitatively to identify patterns and themes., Findings: Most responses indicated lowered confidence on at least one Goal 6 target area, especially managing untreated wastewater and faecal sludge. Both brief and lengthy information formats were valued. WaSH information was perceived as conflicting or unreliable among non-R&L constituencies, suggesting differences in perceptions and information-seeking approaches. While the R&L constituency appeared saturated with learning and training opportunities, others perceived barriers to participating (e.g. not receiving notice or invitation). Research and other WaSH activities were frequently constrained by upward accountability to funders, while stakeholders were inconsistently included in research processes., Policy Implications: This study offers insight into perceived research and decision challenges related to Goal 6 targets. It develops a unified research agenda focused on high priority topics, and recommends renewed attention to evidence synthesis, learning and implementation support, research engagement, and multisectoral coordination.
- Published
- 2020
- Full Text
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28. Evaluating Microbial and Chemical Hazards in Commercial Struvite Recovered from Wastewater.
- Author
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Yee RA, Leifels M, Scott C, Ashbolt NJ, and Liu Y
- Subjects
- Chemical Precipitation, Escherichia coli, Humans, Phosphates, Struvite, Waste Disposal, Fluid, Wastewater
- Abstract
Controlled struvite (NH
4 MgPO4 ·6H2 O) precipitation has become a well-known process for nutrient recovery from wastewater treatment systems to alleviate the pressures of diminishing, finite rock phosphate reservoirs. Nonetheless, coprecipitation of potential microbial and chemical hazards is poorly understood. On the other hand, antimicrobial resistance (AMR) is a major global public health concern and wastewater is thought to disseminate resistance genes within bacteria. Fecal indicator bacteria (FIB) are typically used as measures of treatment quality, and with multiresistant E. coli and Enterococcus spp. rising in concern, the quantification of FIB can be used as a preliminary method to assess the risk of AMR. Focusing on struvite produced from full-scale operations, culture and qPCR methods were utilized to identify FIB, antibiotic resistance genes, and human enteric viruses in the final product. Detection of these hazards occurred in both wet and dry struvite samples indicating that there is a potential risk that needs further consideration. Chemical and biological analyses support the idea that the presence of other wastewater components can impact struvite formation through ion and microbial interference. While heavy metal concentrations met current fertilizer standards, the presence of K, Na, Ca, and Fe ions can impact struvite purity yet provide benefit for agricultural uses. Additionally, the quantified hazards detected varied among struvite samples produced from different methods and sources, thus indicating that production methods could be a large factor in the risk associated with wastewater-recovered struvite. In all, coprecipitation of metals, fecal indicator bacteria, antimicrobial resistance genes, and human enteric viruses with struvite was shown to be likely, and future engineered wastewater systems producing struvite may require additional step(s) to manage these newly identified public health risks.- Published
- 2019
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29. Letter to the Editor RE: High levels of faecal contamination in drinking groundwater and recreational water due to poor sanitation, in the sub-rural neighbourhoods of Kinshasa, Democratic Republic of the Congo by Kayembe et al. 2018.
- Author
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Leifels M, Sirikanchana K, and Mongkolsuk S
- Subjects
- Democratic Republic of the Congo, Feces, Water, Groundwater, Sanitation
- Published
- 2019
- Full Text
- View/download PDF
30. A bioassay-based protocol for chemical neutralization of human faecal wastes treated by physico-chemical disinfection processes: A case study on benzalkonium chloride.
- Author
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Sozzi E, Baloch M, Strasser J, Fisher MB, Leifels M, Camacho J, Mishal N, Elmes SF, Allen G, Gadai G, Valenti L, and Sobsey MD
- Subjects
- Bacteriophage phi 6, Biological Assay, Disinfection methods, Escherichia coli growth & development, Humans, Lecithins chemistry, Polysorbates chemistry, Pseudomonas syringae virology, Waste Disposal, Fluid, Benzalkonium Compounds chemistry, Disinfectants chemistry, Feces microbiology
- Abstract
In situ physico-chemical disinfection of high risk faecal waste is both effective and widely used as a sanitation management strategy for infection prevention and control. Systematic tests where the performance of alternative physico-chemical disinfection methods is systematically compared and optimized must be based on reliable protocols. These protocol are currently not adequately addressing the neutralization related issues: the neutralization of the tested disinfectant after specified conditions of concentration and contact time (CT) is necessary to prevent continued disinfection after the intended contact time; moreover such neutralization is often necessary in practice and on a large scale to prevent adverse health and ecological impacts from remaining disinfectant after the target CT is achieved. Few studies adequately assess the extent of neutralization of the chemical disinfectant and are intended to optimize on-site disinfection practices for waste matrices posing high microbial risks. Hence, there is a need for effective and reproducible neutralization protocols in chemical disinfection trials and practice. Furthermore, for most of chemical disinfectants used in healthcare settings there is no practical methodology to reliably and conveniently measure the residual disinfectant concentration after its neutralization and also determine the optimum concentration of the neutralizer. Because some neutralizing compounds can themselves be toxic to the test microorganisms, it is necessary to optimize neutralization procedures in disinfection experiments for the development of infection control practices using accepted positive control microbes. In the presented work, a stepwise bioassay-based protocol using representative faecal indicator microbes is described for optimizing chemical disinfection and subsequent disinfectant neutralization of any infectious faecal waste matrix. The example described is for the quaternary ammonium compound benzalkonium chloride and its recommended chemical neutralizer in a high strength human faecal waste matrix., (Copyright © 2018 Elsevier GmbH. All rights reserved.)
- Published
- 2019
- Full Text
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31. Distribution of Escherichia coli, coliphages and enteric viruses in water, epilithic biofilms and sediments of an urban river in Germany.
- Author
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Mackowiak M, Leifels M, Hamza IA, Jurzik L, and Wingender J
- Subjects
- Cities, Coliphages isolation & purification, Enterovirus isolation & purification, Escherichia coli isolation & purification, Germany, Biofilms, Environmental Monitoring, Geologic Sediments microbiology, Rivers microbiology, Water Microbiology
- Abstract
Fecal contamination of surface water is commonly evaluated by quantification of bacterial or viral indicators such as Escherichia coli and coliphages, or by direct testing for pathogens such as enteric viruses. Retention of fecally derived organisms in biofilms and sediments is less frequently considered. In this study, we assessed the distribution of E. coli, somatic coliphages, and enteric viruses including human adenovirus (HAdV), enterovirus (EV), norovirus genogroup GII (NoV GII) and group A rotavirus (RoV) in an urban river environment in Germany. 24 samples each of water, epilithic biofilms and sediments were examined. E. coli and somatic coliphages were prevalent not only in the flowing water, but also in epilithic biofilms and sediments, where they were accumulated compared to the overlying water. During enhanced rainfall, E. coli and coliphage concentrations increased by approximately 2.5 and 1 log unit, respectively, in the flowing water, whereas concentrations did not change significantly in epilithic biofilms and sediments. The occurrence of human enteric viruses detected by qPCR was higher in water than in biofilms and sediments. 87.5% of all water samples were positive for HAdV. Enteric viruses found less frequently were EV, RoV and NoV GII in 20.8%, 16.7% and 8.3% of the water samples, respectively. In epilithic biofilms and sediments, HAdV was found in 54.2% and 50.0% of the samples, respectively, and EV was found in 4.2% of both biofilm and sediment samples. RoV and NoV GII were not detected in any of the biofilms and sediments. Overall, the prevalence of enteric viruses was in the order of HAdV > EV > RoV ≥ NoV GII. In conclusion, epilithic biofilms and sediments can be reservoirs for fecal indicators and enteric viruses and thus should be taken into consideration when assessing microbial pollution of surface water environments., (Copyright © 2018 Elsevier B.V. All rights reserved.)
- Published
- 2018
- Full Text
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32. 9th annual international water and health seminar: We get what we give: Water reuse coalesces prominent water and health topics.
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Leifels M, Manasfi T, and Setty K
- Subjects
- Public Health, Recycling, Wastewater, Water Pollution, Water Quality, Water Supply
- Published
- 2018
- Full Text
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33. Relative Abundance of Human Bocaviruses in Urban Sewage in Greater Cairo, Egypt.
- Author
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Hamza H, Leifels M, Wilhelm M, and Hamza IA
- Subjects
- Egypt, Feces virology, Genotype, Human bocavirus classification, Human bocavirus genetics, Human bocavirus growth & development, Humans, Parvoviridae Infections virology, Phylogeny, Water Pollution, Human bocavirus isolation & purification, Sewage virology
- Abstract
Human bocavirus (HBoV) is predominantly found in the respiratory tract infections and in the stool of patients with gastroenteritis symptoms. However, data on the prevalence of HBoV genotypes in environmental samples are limited. Here we addressed the prevalence of HBoV in sewage collected from three different wastewater treatment plants in Egypt. HBoV-1, HBoV-2, and HBoV-3 were detected, whereas none of the samples were positive for HBoV-4. The median concentration of HBoV in influent samples was 8.5 × 10
3 GC/l for HBoV-1, 3.0 × 104 GC/l for HBoV-2, and 2.5 × 104 GC/l for HBoV-3. The concentration was reduced but not completely removed in the effluent samples. The median concentration in the outlet samples was 2.9 × 103 GC/l for HBoV-1, 4.1 × 103 GC/l for HBoV-2, and 2.1 × 103 GC/l for HBoV-3. Moreover, no seasonality pattern of HBoVs was found. The high incidence of HBoV in sewage samples provided an evidence of its circulation in the local population. Although the role of HBoV in respiratory or gastro-intestinal infections still remains to be fully elucidated, the risk of infection via contaminated water should be taken into consideration.- Published
- 2017
- Full Text
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34. Editorial 8th International Water and Health Seminar.
- Author
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Leifels M and Delaire C
- Subjects
- Developed Countries, Developing Countries, Global Health, Government Regulation, Humans, Drinking Water, Human Rights, Sanitation legislation & jurisprudence
- Published
- 2017
- Full Text
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35. From Lab to Lake - Evaluation of Current Molecular Methods for the Detection of Infectious Enteric Viruses in Complex Water Matrices in an Urban Area.
- Author
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Leifels M, Hamza IA, Krieger M, Wilhelm M, Mackowiak M, and Jurzik L
- Subjects
- Azides chemistry, Humans, Lakes, Propidium analogs & derivatives, Propidium chemistry, Enterovirus genetics, Real-Time Polymerase Chain Reaction methods, Rivers virology, Sewage virology, Urban Renewal, Water Microbiology
- Abstract
Quantitative PCR methods are commonly used to monitor enteric viruses in the aquatic environment because of their high sensitivity, short reaction times and relatively low operational cost. However, conclusions for public health drawn from results of such molecular techniques are limited due to their inability to determine viral infectivity. Ethidium monoazide (EMA) and propidium monoazide (PMA) are capable to penetrate the damaged or compromised capsid of the inactivated viruses and bind to the viral nucleic acids. We assessed whether dye treatment is a suitable approach to improve the ability of qPCR to distinguish between infectious and non-infectious human adenovirus, enterovirus and rotavirus A in surface water of an urban river and sewage before and after UV disinfection. Like the gold standard of cell culture assays, pretreatment EMA-/PMA-qPCR succeeded in removing false positive results which would lead to an overestimation of the viral load if only qPCR of the environmental samples was considered. A dye pretreatment could therefore provide a rapid and relatively inexpensive tool to improve the efficacy of molecular quantification methods in regards to viral infectivity., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2016
- Full Text
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36. [Undulant fever and autoimmune hemolytic anemia in a 20-year-old exchange student from Jordan - the human brucellosis as an important differential diagnosis in migrants].
- Author
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Trawinski H, Gräber S, Leifels M, Schubert S, and Lübbert C
- Subjects
- Animals, Brucellosis transmission, Comorbidity, Diagnosis, Differential, Food Microbiology, Germany, Humans, Jordan ethnology, Male, Milk microbiology, Pasteurization, Sheep, Yogurt microbiology, Young Adult, Anemia, Hemolytic, Autoimmune diagnosis, Brucellosis diagnosis, Emigrants and Immigrants, International Educational Exchange
- Abstract
History and Clinical Findings: A 20-year-old Jordanian exchange student presents with recurrent fever, night sweats, cough, and swelling and redness around the ankle. Physical examination further reveals bilateral ankle arthritis and painful cervical lymphadenopathy., Investigations and Diagnosis: Laboratory tests show signs of autoimmune hemolytic anemia, elevated liver function tests, and moderate laboratory signs of inflammation. All blood cultures reveal growth of gram-negative coccoid rods which are initially identified by mass spectrometry as Moraxella lacunata and Ochrobactrum anthropi. However, antimicrobial therapy with imipenem / cilastatin does not improve the patient's clinical condition. Based on the travel history including consumption of yogurt from unpasteurized sheep's milk, we perform serological tests with a strongly positive result for Brucella species, and additional work-up of blood culture isolates confirm the definitive diagnosis of brucellosis (Malta fever, infection by Brucella melitensis)., Treatment and Course: After initiation of antimicrobial therapy with doxycycline and rifampin the patient shows complete resolution of fever. Arthritis, autoimmune hemolytic anemia and accompanying hepatitis improve in the course., Conclusions: Thus, since brucellosis is endemic to countries like Jordan, it should be considered as a possible agent of fever of unknown origin especially in migrants unresponsive to empiric therapy and appropriate diagnostic tests including meticulous validation of blood cultures should be performed. Standard therapy is a combination of doxycycline with rifampin for at least 6 weeks., (© Georg Thieme Verlag KG Stuttgart · New York.)
- Published
- 2015
- Full Text
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37. Use of ethidium monoazide and propidium monoazide to determine viral infectivity upon inactivation by heat, UV- exposure and chlorine.
- Author
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Leifels M, Jurzik L, Wilhelm M, and Hamza IA
- Subjects
- Biological Assay, Cell Culture Techniques, DNA, Viral, Disinfection methods, Ethidium, Humans, Propidium analogs & derivatives, Public Health, Water Microbiology, Adenoviruses, Human drug effects, Adenoviruses, Human radiation effects, Azides, Chlorine, Hot Temperature, Polymerase Chain Reaction methods, Ultraviolet Rays, Virus Inactivation
- Abstract
Despite the great sensitivity of PCR in monitoring enteric viruses in an aquatic environment, PCR detects viral nucleic acids of both infectious and noninfectious viruses, limiting the conclusions regarding significance for public health. Ethidium monoazide (EMA) and propidium monoazide (PMA) are closely related membrane impermeant dyes that selectively penetrate cells with compromised membranes. Inside the cells, the dye can intercalate into nucleic acids and inhibit PCR amplification. To assess whether EMA and PMA pretreatment is a suitable approach to inhibit DNA amplification from noninfectious viruses upon heat treatment, UV exposure or chlorine treatment, viruses were measured by qPCR, EMA-qPCR, PMA-qPCR and cell culture titration. EMA/PMA-qPCR of UV- and heat-treated viruses did not correlate with the results of the cell culture assay. However, the data from EMA/PMA-qPCR of chlorine-inactivated viruses was consistent with the cell culture infectivity assay. Therefore, a dye treatment approach could be a rapid and inexpensive tool to screen the efficacy of chlorine disinfection, but it is not able to distinguish between infectious and noninfectious viruses inactivated via heat treatment or UV irradiation. Indeed, different viruses may have different trends and mechanisms of inactivation; thus, the assay must be evaluated for each virus separately., (Copyright © 2015 Elsevier GmbH. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
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