Water Microorganisms Associated with Human Health, 2nd Edition

A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Public Health Microbiology".

Deadline for manuscript submissions: 30 September 2025 | Viewed by 2324

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ICBAS—UP, Institute of Biomedical Sciences Abel Salazar, University of Porto, Rua Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal
Interests: antibiotic resistance; drinking water; water analysis
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Special Issue Information

Dear Colleagues,

This Special Issue is the continuation of our previous Special Issue, entitled “Water Microorganisms Associated with Human Health”.

Water and human health are closely intertwined. Water is essential to life but is also a primordial exposure pathway to potentially pathogenic microorganisms and chemical agents. Universal and equitable access to safe and affordable drinking water is recognized as a basic human right and is one of the United Nations’ Sustainable Development Goals. However, the World Health Organization estimates that about 2.2 billion people still live without access to safe water, with most of them being in low-income countries. On the other hand, outbreaks linked to recreational water bathing and ongoing climate change are increasing, including in the Northern Hemisphere. The recent World Health Organization guidelines on bathing water quality identified potential pathogenic anthropogenic sources and naturally occurring microorganisms of possible concern, thus highlighting the need for research to understand the associated microbial ecology. Increasing knowledge leads to the need to revise and update standards and guidelines almost permanently, both for legal criteria and recently identified contaminants. Finally, public health problems related to water quality are expected to increase in upcoming years under the current climate change and population growth scenario. Newly integrated knowledge is pivotal to developing risk assessment tools and mitigation strategies. This Special Issue aims to bridge the gap in knowledge, bringing together the most recent research on the association between water quality and human health. In this Special Issue, original research articles and reviews are welcome. Suggested topic areas include (but are not limited to) new integrated risk assessment schemes, water quality indicators, microbial source tracking, novel detection methods, environmental exposure, and the association between climate change and water quality.

Dr. Ana Machado
Guest Editor

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Keywords

  • drinking water
  • recreational water
  • microorganisms
  • biomarkers
  • emerging contaminants
  • risk assessment
  • waterborne diseases
  • One Health

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Published Papers (4 papers)

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Research

18 pages, 9709 KiB  
Article
Waterborne Transmission Driving the Prevalence of Blastocystis sp. in Los Ríos Region, Southern Chile
by Daniel Sanhueza Teneo, Cedric B. Chesnais, Javiera Manzano, María Paz Moll, Analía Téllez and Guillermo Valenzuela-Nieto
Microorganisms 2025, 13(7), 1549; https://doi.org/10.3390/microorganisms13071549 - 1 Jul 2025
Viewed by 334
Abstract
Waterborne gastrointestinal infections remain a global health concern, with approximately 1.7 billion diarrhea-related illnesses annually attributable to protozoan parasites. These pathogens are transmitted through contaminated water and exhibit high resistance to chlorination, posing substantial challenges to effective water treatment. This study focused on [...] Read more.
Waterborne gastrointestinal infections remain a global health concern, with approximately 1.7 billion diarrhea-related illnesses annually attributable to protozoan parasites. These pathogens are transmitted through contaminated water and exhibit high resistance to chlorination, posing substantial challenges to effective water treatment. This study focused on the most prevalent intestinal parasites in the Los Ríos Region of Chile: Blastocystis sp., Giardia duodenalis, and Entamoeba coli. The objectives were to assess the prevalence of eukaryotic parasites in water samples—covering both drinking and recreational sources—to describe the circulating subtypes of Blastocystis sp. and to identify ecological factors associated with parasite presence. Water samples were analyzed using conventional PCR, next-generation sequencing (NGS) was employed for Blastocystis sp. subtype identification, and the environmental predictors were evaluated using a multivariable logistic regression model. A total of 132 water samples were analyzed, of which 15.2% were positive for Blastocystis sp. and 1.5% for E. coli, while no samples tested positive for G. duodenalis. We identified subtypes ST1–ST4 of Blastocystis sp., along with ST7, ST10, ST14, ST21, and ST23–ST26, the latter being reported for the first time in Chile. Ecological factors significantly associated with Blastocystis sp. presence included higher water temperature and greater rainfall at positive sites. Potable water was associated with significantly lower odds of Blastocystis sp. infection (aOR = 0.04, 95% CI: 0.00–0.87; p = 0.041), while precipitation increased infection odds by 3% per additional millimeter (aOR = 1.03, 95% CI: 1.00–1.06; p = 0.036). Greater distance to the nearest farmhouse was also significantly associated with reduced infection risk, suggesting that proximity to livestock environments may influence Blastocystis sp. transmission. These findings help explain the high prevalence of Blastocystis sp. observed in humans in the Los Ríos Region and highlight the pivotal role of ecological conditions in driving waterborne transmission. To our knowledge, this is the first environmental study in Chile to clearly demonstrate the association between human infection, environmental factors, and the transmission dynamics of Blastocystis sp. Full article
(This article belongs to the Special Issue Water Microorganisms Associated with Human Health, 2nd Edition)
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13 pages, 2691 KiB  
Article
Interaction of Acanthamoeba T5 with a Vero Cell Culture: An Exploratory Study Using Live-Cell Imaging and Confocal Microscopy
by Elizabeth Abrahams-Sandi, Mónica Prado-Porras, Johan Alvarado-Ocampo, Jacob Lorenzo-Morales and Lissette Retana-Moreira
Microorganisms 2025, 13(7), 1460; https://doi.org/10.3390/microorganisms13071460 - 24 Jun 2025
Viewed by 282
Abstract
Acanthamoeba is a free-living amoeba widely distributed in nature, responsible for clinical cases of encephalitis and keratitis in humans. Due to the increase in the number of cases in recent years, understanding the damage mechanisms employed by the amoeba is very important for [...] Read more.
Acanthamoeba is a free-living amoeba widely distributed in nature, responsible for clinical cases of encephalitis and keratitis in humans. Due to the increase in the number of cases in recent years, understanding the damage mechanisms employed by the amoeba is very important for the clinical management of the disease, development of diagnostic tools and identification of therapeutic targets. To date, most experimental studies to determine the virulence factors and pathogenesis of Acanthamoeba have employed genotype T4 as an infection model, resulting in minimal information regarding other genotypes. In this work, we explored the direct and indirect effect of A. lenticulata genotype T5 trophozoites and their excretion/secretion products over a Vero cell monolayer. Using confocal and real-time microscopy, we witnessed a significant direct mechanical action of the trophozoites on the cells during the adhesion stage. Additionally, we observed the formation of digitiform phagocytic structures through which the nuclear material of the target cell appears to be specifically sucked by the amoeba without the involvement of any lytic mechanism. Moreover, an increase in lysosomal activity in the cytoplasm of trophozoites of Acanthamoeba, and the effect of the excretion/secretion products on the actin filaments of the target cells were observed during the first 2–3 h post-infection. Full article
(This article belongs to the Special Issue Water Microorganisms Associated with Human Health, 2nd Edition)
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20 pages, 2378 KiB  
Article
Virulence and Antibiotic Resistance Genes in Enterococcus from Wastewater for Reuse and Their Health Impact
by Anthony A. Adegoke, Chibuzor E. Madu, Poovendhree Reddy, Opeyemi K. Fatunla, Thor A. Stenström and Anthony I. Okoh
Microorganisms 2025, 13(5), 1045; https://doi.org/10.3390/microorganisms13051045 - 30 Apr 2025
Viewed by 681
Abstract
Virulence attributes and putative antibiotic resistance genes from enterococcal isolates from wastewater treatment facilities for sustainable reuse and the areas where they discharge treated water were assessed using phenotypic and molecular methods. This analysis was performed on 269 Enterococci, of which 202 were [...] Read more.
Virulence attributes and putative antibiotic resistance genes from enterococcal isolates from wastewater treatment facilities for sustainable reuse and the areas where they discharge treated water were assessed using phenotypic and molecular methods. This analysis was performed on 269 Enterococci, of which 202 were vancomycin-resistant Enterococcus (VRE). VRE strains show markedly higher resistance across multiple antibiotics, especially glycopeptides and beta-lactams, compared to the more susceptible profile observed in vancomycin-susceptible Enterococcus (VSE) strains. vanC was found in every instance of E. gallinarum among VRE and enterococci susceptible to vancomycin (VSE) isolates but not in VR E. faecium/faecalis. Among VRE, 127 (62.9%) possessed at least one of the tetK, tetL, tetM, or tetO, while 22 (17.3%) had two of these genes. The multidrug efflux pump gene emeA was detected in 27 out of 202 (13.4%) VRE isolates and 8 out of 67 (11.9%) VSE isolates. Exactly 69 (78.4%) possessed at least one of the virulence determinants tested, with 10 (11.4%) and seven (8%) positive for haemolysis and gelatinase activity respectively. The gelatinase gene, gelE, was detected in 16 (18.1%) isolates, while more isolates (n = 23; 26.1%) were positive for gelatinase activity. Cytolytic (cyl) genes (1.1%), Angiotensin-converting-enzyme genes (ace) (13.6%), endocarditis-specific antigen A genes (efaA) (25%), hyaluronidase (hyl) genes (9.1%), enterococcal surface protein (esp) genes (4.5%), among others, were detected. Gelatinase activity and the amplified virulence genes were further validated by sequencing the gel-positive amplicons, which were almost identical (98.97%), and the gelE gene of Enterococcus sp. strain SQ07C was deposited under the GenBank accession number PQ381122. Overall, our results showed that the enterococcal isolates were considered as potential pathogens of notable threat to human health via exposure through reuse, and there is a need for more stringent treatment protocols. Full article
(This article belongs to the Special Issue Water Microorganisms Associated with Human Health, 2nd Edition)
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13 pages, 937 KiB  
Article
Anthropogenic Blastocystis from Drinking Well and Coastal Water in Guinea-Bissau (West Africa)
by Sara Gomes-Gonçalves, Ana Machado, Adriano Bordalo and João R. Mesquita
Microorganisms 2025, 13(3), 620; https://doi.org/10.3390/microorganisms13030620 - 7 Mar 2025
Viewed by 720
Abstract
This study provides the first comprehensive investigation of Blastocystis sp. contamination in the drinking well and coastal water sources in Guinea-Bissau, a region grappling with severe water quality challenges. Of the forty-five water samples analyzed (34 well and 9 coastal water sources), Blastocystis [...] Read more.
This study provides the first comprehensive investigation of Blastocystis sp. contamination in the drinking well and coastal water sources in Guinea-Bissau, a region grappling with severe water quality challenges. Of the forty-five water samples analyzed (34 well and 9 coastal water sources), Blastocystis sp. was detected in five (11%, 95% CI: 3.71–24.05) of the wells, which serve as a critical and primary drinking source for local communities. The detection of human-associated Blastocystis sp. subtype (ST)2 and ST3 raises concerns about the potential of fecal contamination as a transmission route for Blastocystis sp., underscoring the public health risks associated with an inadequate WASH (water, sanitation, and hygiene) infrastructure. These findings highlight the urgent need for improved water management and further research on waterborne parasitic infections in resource-limited settings. Full article
(This article belongs to the Special Issue Water Microorganisms Associated with Human Health, 2nd Edition)
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