Waterborne Transmission Driving the Prevalence of <i>Blastocystis</i> sp. in Los Ríos Region, Southern Chile

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 ch...

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Main Authors: Daniel Sanhueza Teneo, Cedric B. Chesnais, Javiera Manzano, María Paz Moll, Analía Téllez, Guillermo Valenzuela-Nieto
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Microorganisms
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Online Access:https://www.mdpi.com/2076-2607/13/7/1549
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author Daniel Sanhueza Teneo
Cedric B. Chesnais
Javiera Manzano
María Paz Moll
Analía Téllez
Guillermo Valenzuela-Nieto
author_facet Daniel Sanhueza Teneo
Cedric B. Chesnais
Javiera Manzano
María Paz Moll
Analía Téllez
Guillermo Valenzuela-Nieto
author_sort Daniel Sanhueza Teneo
collection DOAJ
description 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: <i>Blastocystis</i> sp., <i>Giardia duodenalis</i>, and <i>Entamoeba coli</i>. 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 <i>Blastocystis</i> sp. and to identify ecological factors associated with parasite presence. Water samples were analyzed using conventional PCR, next-generation sequencing (NGS) was employed for <i>Blastocystis</i> 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 <i>Blastocystis</i> sp. and 1.5% for <i>E. coli</i>, while no samples tested positive for <i>G. duodenalis</i>. We identified subtypes ST1–ST4 of <i>Blastocystis</i> 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 <i>Blastocystis</i> sp. presence included higher water temperature and greater rainfall at positive sites. Potable water was associated with significantly lower odds of <i>Blastocystis</i> sp. infection (aOR = 0.04, 95% CI: 0.00–0.87; <i>p</i> = 0.041), while precipitation increased infection odds by 3% per additional millimeter (aOR = 1.03, 95% CI: 1.00–1.06; <i>p</i> = 0.036). Greater distance to the nearest farmhouse was also significantly associated with reduced infection risk, suggesting that proximity to livestock environments may influence <i>Blastocystis</i> sp. transmission. These findings help explain the high prevalence of <i>Blastocystis</i> 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 <i>Blastocystis</i> sp.
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spelling doaj-art-b8a18407a8ba4071bbaa8f80c33332a82025-08-20T03:07:55ZengMDPI AGMicroorganisms2076-26072025-07-01137154910.3390/microorganisms13071549Waterborne Transmission Driving the Prevalence of <i>Blastocystis</i> sp. in Los Ríos Region, Southern ChileDaniel Sanhueza Teneo0Cedric B. Chesnais1Javiera Manzano2María Paz Moll3Analía Téllez4Guillermo Valenzuela-Nieto5Instituto de Inmunología y Parasitología, Facultad de Medicina, Universidad Austral de Chile, Valdivia 5110566, ChileTransVIHMI, INSERM Unité, Institut de Recherche pour le Développement (IRD), Montpellier University, 34090 Montpellier, FranceInstituto de Inmunología y Parasitología, Facultad de Medicina, Universidad Austral de Chile, Valdivia 5110566, ChileInstituto de Inmunología y Parasitología, Facultad de Medicina, Universidad Austral de Chile, Valdivia 5110566, ChileInstituto de Inmunología y Parasitología, Facultad de Medicina, Universidad Austral de Chile, Valdivia 5110566, ChileFacultad de Ciencias para el Cuidado de la Salud, Universidad San Sebastián, Valdivia 5090000, ChileWaterborne 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: <i>Blastocystis</i> sp., <i>Giardia duodenalis</i>, and <i>Entamoeba coli</i>. 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 <i>Blastocystis</i> sp. and to identify ecological factors associated with parasite presence. Water samples were analyzed using conventional PCR, next-generation sequencing (NGS) was employed for <i>Blastocystis</i> 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 <i>Blastocystis</i> sp. and 1.5% for <i>E. coli</i>, while no samples tested positive for <i>G. duodenalis</i>. We identified subtypes ST1–ST4 of <i>Blastocystis</i> 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 <i>Blastocystis</i> sp. presence included higher water temperature and greater rainfall at positive sites. Potable water was associated with significantly lower odds of <i>Blastocystis</i> sp. infection (aOR = 0.04, 95% CI: 0.00–0.87; <i>p</i> = 0.041), while precipitation increased infection odds by 3% per additional millimeter (aOR = 1.03, 95% CI: 1.00–1.06; <i>p</i> = 0.036). Greater distance to the nearest farmhouse was also significantly associated with reduced infection risk, suggesting that proximity to livestock environments may influence <i>Blastocystis</i> sp. transmission. These findings help explain the high prevalence of <i>Blastocystis</i> 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 <i>Blastocystis</i> sp.https://www.mdpi.com/2076-2607/13/7/1549parasitologypublic healthwaterborne pathogens<i>Blastocystis</i> sp.one healthenvironmental factors
spellingShingle Daniel Sanhueza Teneo
Cedric B. Chesnais
Javiera Manzano
María Paz Moll
Analía Téllez
Guillermo Valenzuela-Nieto
Waterborne Transmission Driving the Prevalence of <i>Blastocystis</i> sp. in Los Ríos Region, Southern Chile
Microorganisms
parasitology
public health
waterborne pathogens
<i>Blastocystis</i> sp.
one health
environmental factors
title Waterborne Transmission Driving the Prevalence of <i>Blastocystis</i> sp. in Los Ríos Region, Southern Chile
title_full Waterborne Transmission Driving the Prevalence of <i>Blastocystis</i> sp. in Los Ríos Region, Southern Chile
title_fullStr Waterborne Transmission Driving the Prevalence of <i>Blastocystis</i> sp. in Los Ríos Region, Southern Chile
title_full_unstemmed Waterborne Transmission Driving the Prevalence of <i>Blastocystis</i> sp. in Los Ríos Region, Southern Chile
title_short Waterborne Transmission Driving the Prevalence of <i>Blastocystis</i> sp. in Los Ríos Region, Southern Chile
title_sort waterborne transmission driving the prevalence of i blastocystis i sp in los rios region southern chile
topic parasitology
public health
waterborne pathogens
<i>Blastocystis</i> sp.
one health
environmental factors
url https://www.mdpi.com/2076-2607/13/7/1549
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