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Blastocystis is the most prevalent intestinal eukaryotic microorganism with significant impacts on both human and animal health. Despite extensive research, its pathogenicity remains controversial. The COST Action CA21105, " Blastocystis under One Health" (OneHealthBlastocystis), aims to bridge gaps in our understanding by fostering a multidisciplinary network. This initiative focuses on developing standardised diagnostic methodologies, establishing a comprehensive subtype and microbiome databank, and promoting capacity building through education and collaboration. The Action is structured into five working groups, each targeting specific aspects of Blastocystis research, including epidemiology, diagnostics, 'omics technologies, in vivo and in vitro investigations, and data dissemination. By integrating advances across medical, veterinary, public, and environmental health, this initiative seeks to harmonise diagnostics, improve public health policies, and foster innovative research, ultimately enhancing our understanding of Blastocystis and its role in health and disease. This collaborative effort is expected to lead to significant advancements and practical applications, benefiting the scientific community and public health.
Blastocystis is a common microorganism found in the intestines of humans and animals. Its role in causing disease is still debated among scientists. The " Blastocystis under One Health" initiative aims to unite experts from human medicine, veterinary science, and environmental science to better understand this microorganism and its health effects. The project focuses on improving diagnostic methods, creating a comprehensive database of Blastocystis samples, and analysing its genetic and molecular makeup. Researchers will also study how Blastocystis interacts with other gut microbes and impacts gut health. Additionally, the initiative aims to educate healthcare professionals and the public about Blastocystis. By working together, scientists hope to develop better ways to diagnose, treat (if necessary), and/or prevent Blastocystis infections, ultimately protecting both human and animal health and enhancing our understanding of this widespread microorganism.
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Blastocystis is a ubiquitous, widely distributed protist inhabiting the gastrointestinal tract of humans and other animals. The organism is genetically diverse, and so far, at least 28 subtypes (STs) have been identified with ST1-ST9 being the most common in humans. The pathogenicity of Blastocystis is controversial. Several routes of transmission have been proposed including fecal-oral (e.g., zoonotic, anthroponotic) and waterborne. Research on the latter has gained traction in the last few years with the organism having been identified in various bodies of water, tap water, and rainwater collection containers including water that has been previously filtered and/or chlorinated. Herein, we assessed the resistance of 11 strains maintained in culture, spanning ST1-ST9 to various chlorine and hydrogen peroxide concentrations for 24 h, and performed recovery assays along with re-exposure. Following the treatment with both compounds, all subtypes showed increased resistance, and viability could be visualized at the cellular level. These results are hinting at the presence of mechanism of resistance to both chlorine and hydrogen peroxide. As such, this pilot study can be the platform for developing guidelines for water treatment processes.
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Infecciones por Blastocystis , Blastocystis , Humanos , Animales , Cloro/farmacología , Peróxido de Hidrógeno/farmacología , Proyectos Piloto , Variación Genética , Heces , Prevalencia , FilogeniaRESUMEN
Blastocystis is the most commonly found intestinal protist in the world. Accurate detection and differentiation of Blastocystis including its subtypes (arguably species) are essential to understand its epidemiology and role in human health. We compared (i) the sensitivity of conventional PCR (cPCR) and qPCR in a set of 288 DNA samples obtained from stool samples of gut-healthy individuals, and (ii) subtype diversity as detected by next-generation sequencing (NGS) versus Sanger sequencing. Real-time PCR resulted in more positive samples than cPCR, revealing high fecal load of Blastocystis based on the quantification curve in most samples. In subtype detection, NGS was largely in agreement with Sanger sequencing but showed higher sensitivity for mixed subtype colonization within one host. This fact together with use of the combination of qPCR and NGS and obtaining information on the fecal protist load will be beneficial for epidemiological and surveillance studies.
Title: Comparaison des approches de diagnostic moléculaire pour la détection et la différenciation du protiste intestinal Blastocystis sp. chez l'homme. Abstract: Blastocystis est le protiste intestinal le plus répandu dans le monde. La détection et la différenciation précises de Blastocystis, y compris ses sous-types (sans doute des espèces), sont essentielles pour comprendre son épidémiologie et son rôle dans la santé humaine. Nous avons comparé (i) la sensibilité de la PCR conventionnelle (cPCR) et de la qPCR dans un ensemble de 288 échantillons d'ADN obtenus à partir d'échantillons de selles d'individus en bonne santé intestinale et (ii) la diversité des sous-types détectée par le séquençage de nouvelle génération (NGS) par rapport au séquençage Sanger. La PCR en temps réel a donné plus d'échantillons positifs que la cPCR, révélant une charge fécale élevée de Blastocystis sur la base de la courbe de quantification dans la plupart des échantillons. Dans la détection des sous-types, le NGS était largement en accord avec le séquençage de Sanger mais a montré une sensibilité plus élevée pour la colonisation de sous-types mixtes au sein d'un hôte. Ce fait, associé à l'utilisation de la combinaison de qPCR et de NGS et à l'obtention d'informations sur la charge fécale de protistes, sera bénéfique pour les études épidémiologiques et de surveillance.
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Infecciones por Blastocystis , Blastocystis , Blastocystis/genética , Infecciones por Blastocystis/diagnóstico , Infecciones por Blastocystis/epidemiología , Heces , Humanos , Patología Molecular , Reacción en Cadena en Tiempo Real de la PolimerasaRESUMEN
The present study aimed to estimate the prevalence of zoonotic pathogens Giardia duodenalis, Cryptosporidium spp., Toxoplasma gondii and Erysipelothrix in muskoxen (Ovibos moschatus) and sheep (Ovis aries) from Greenland. In 2017 and 2018, faecal samples were collected from wild muskoxen from three distinct populations (Zackenberg, Kangerlussuaq, and Ivittuut) and from domestic sheep from southwest Greenland. Blood samples were collected from muskoxen from Kangerlussuaq and Ivittuut and from sheep. Faecal samples were tested for specific DNA of G. duodenalis and Cryptosporidium spp., and blood samples were tested for antibodies against T. gondii and Erysipelothrix. The estimated prevalence of G. duodenalis was 0% (0/58), 17% (7/41) and 0% (0/55) in muskoxen from Zackenberg, Kangerlussuaq and Ivittuut, respectively, and 37% (16/43) in sheep. The estimated prevalence of Cryptosporidium was 0% (0/58), 2% (1/41), 7% (4/55) in muskoxen from Zackenberg, Kangerlussuaq, Ivittuut, respectively, and 2% (1/43) in sheep. Neither Giardia nor Cryptosporidium were detected in winter samples (0/78). Of the positive samples, Giardia from one muskox sample only was successfully typed as G. duodenalis assemblage A, and Cryptosporidium from two muskoxen was successfully typed as C. parvum, subtype IIdA20G1e. The estimated T. gondii seroprevalence was 2% (1/44) and 0% (0/8) in muskoxen from Kangerlussuaq and Ivittuut, respectively, and 1% (1/155) in sheep. The estimated Erysipelothrix seroprevalence was 2% (1/45) and 13% (1/8) in muskoxen from Kangerlussuaq and Ivittuut, respectively, and 7% (10/150) in sheep. The results of this study add to the scarce knowledge on zoonotic pathogens in the Arctic.
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Criptosporidiosis , Cryptosporidium , Enfermedades de las Ovejas , Animales , Criptosporidiosis/epidemiología , Cryptosporidium/genética , Groenlandia , Estudios Seroepidemiológicos , Ovinos , Enfermedades de las Ovejas/epidemiología , Oveja DomésticaRESUMEN
The gut microbiota (GM) displays a profound ability to adapt to extrinsic factors, such as gastrointestinal pathogens and/or dietary alterations. Parasitic worms (helminths) and host-associated GM share a long co-evolutionary relationship, exerting mutually modulatory effects which may impact the health of the host. Moreover, dietary components such as prebiotic fibers (e.g. inulin) are capable of modulating microbiota toward a composition often associated with a healthier gut function. The effect of helminth infection on the host microbiota is still equivocal, and it is also unclear how parasites and prebiotic dietary components interact to influence the microbiota and host health status. Some helminths, such as Trichuris suis (porcine whipworm), also exhibit strong immunomodulatory and anti-inflammatory effects. We therefore explored the effects of T. suis, alone and in interaction with inulin, both in fecal microbiota during the infection period and luminal microbiota across four intestinal segments at the end of a 4-week infection period. We observed that T. suis generally had minimal, but mainly positive, effects on the microbiota. T. suis increased the relative abundance of bacterial genera putatively associated with gut health such as Prevotella, and decreased bacteria such as Proteobacteria that have been associated with dysbiosis. Interestingly, dietary inulin interacted with T. suis to enhance these effects, thereby modulating the microbiota toward a composition associated with reduced inflammation. Our results show that administration of T. suis together with the consumption of prebiotic inulin may have the potential to positively affect gut health.
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Host-parasite interactions may be modulated by host- or parasite-associated microbes, but the role of these are often overlooked. Particularly for parasites with intestinal stages (either larval or adult), the host gut microbiome may play a key role for parasite establishment; moreover, the microbiome may change in response to invading parasites. Hypothesis testing at the organismal level may be hampered, particularly in mammalian definitive hosts, by ethical, logistical, and economical restrictions. Thus, invertebrates naturally serving as intermediate hosts to parasites with complex life cycles may inform the development of mammalian models as an early-stage host-parasite model. In addition, several important pathogens are vectored by insects, and insect gut microbiome-pathogen interactions may provide essential base-line knowledge, which may be used to control vectorborne pathogens. Here, we used the grain beetle, Tenebrio molitor, a host of the tapeworm Hymenolepis diminuta, to explore interactions between infection status and resident gut microbiota at two pre-determined time points (day two and seven) post infection. Using 16S/18S microbial profiling, we measured key parameters of the composition, relative abundance, and diversity of the host gut bacteriome and mycobiome. In addition, we quantified the systemic beetle immune response to infection by Phenoloxidase activity and hemocyte abundance. We found significant changes in the gut bacteriome and mycobiome in relation to infection status and beetle age. Thus, the relative abundance of Proteobacteria was significantly higher in the gut of infected beetles and driven mostly by an increased abundance of Acinetobacter. In addition, the mycobiome was less abundant in infected beetles but maintained higher Shannon diversity in infected compared with non-infected beetles. Beetles treated with a broad-spectrum antibiotic (Tetracycline) exhibited significantly reduced parasite establishment compared with the untreated control group, indicating that the host microbiome may greatly influence hatching of eggs and subsequent establishment of H. diminuta larvae. Our results suggest that experimental work using invertebrates may provide a platform for explorative studies of host-parasite-microbe interactions and their underlying mechanisms.
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Escarabajos/parasitología , Microbioma Gastrointestinal , Hymenolepis diminuta/fisiología , Animales , Antibacterianos/farmacología , Escarabajos/inmunología , ADN Bacteriano/aislamiento & purificación , ADN Bacteriano/metabolismo , Microbioma Gastrointestinal/efectos de los fármacos , Hemolinfa/metabolismo , Interacciones Huésped-Parásitos , Monofenol Monooxigenasa/metabolismo , Micobioma/efectos de los fármacos , Análisis de Componente Principal , Proteobacteria/genética , Proteobacteria/aislamiento & purificación , Tetraciclina/farmacologíaRESUMEN
Diet composition may play a crucial role in shaping host immune responses and commensal gut microbiota populations. Bioactive dietary components, such as inulin, have been extensively studied for their bioactive properties, particularly in modulating gut immune function and reducing inflammation. It has been shown that colonization with gastrointestinal parasitic worms (helminths) may alleviate chronic inflammation through promotion of T-helper cell type (Th) 2 and T-regulatory immune responses and alterations in the gut microbiome. In this study, we investigated if dietary inulin could modulate mucosal immune function in pigs during colonization with the porcine whipworm Trichuris suis. T. suis infection induced a typical Th2-biased immune response characterized by transcriptional changes in Th2- and barrier function-related genes, accompanied by intestinal remodeling through increased epithelial goblet and tuft cell proliferation. We observed that inulin also up-regulated Th2-related immune genes (IL13, IL5), and suppressed Th1-related pro-inflammatory genes (IFNG, IL1A, IL8) in the colon. Notably, inulin augmented the T. suis-induced responses with increased transcription of key Th2 and mucosal barrier genes (e.g., IL13, TFF3), and synergistically suppressed pro-inflammatory genes, such as IFNG and CXCL9. 16S rRNA sequencing of proximal colon digesta samples revealed that inulin supplementation reduced the abundance of bacterial phyla linked to inflammation, such as Proteobacteria and Firmicutes, and simultaneously increased Actinobacteria and Bacteroidetes. Interestingly, pigs treated with both inulin and T. suis displayed the highest Bacteroidetes: Firmicutes ratio and the lowest gut pH, suggesting an interaction of diet and helminth infection that stimulates the growth of beneficial bacterial species. Overall, our data demonstrate that T. suis infection and inulin co-operatively enhance anti-inflammatory immune responses, which is potentially mediated by changes in microbiota composition. Our results highlight the intricate interactions between diet, immune function and microbiota composition in a porcine helminth infection model. This porcine model should facilitate further investigations into the use of bioactive diets as immunomodulatory mediators against inflammatory conditions, and how diet and parasites may influence gut health.
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Mucosa Intestinal/inmunología , Inulina/inmunología , Porcinos/inmunología , Porcinos/parasitología , Células Th2/inmunología , Tricuriasis/inmunología , Trichuris/inmunología , Animales , Colon/inmunología , Colon/parasitología , Dieta/métodos , Femenino , Microbioma Gastrointestinal/inmunología , Inflamación/inmunología , Inflamación/parasitología , Mucosa Intestinal/parasitología , Masculino , Membrana Mucosa/inmunología , Membrana Mucosa/parasitología , ARN Ribosómico 16S/inmunología , Enfermedades de los Porcinos/inmunología , Enfermedades de los Porcinos/parasitología , Tricuriasis/parasitología , Tricuriasis/veterinariaRESUMEN
AIM: The aim of the present study was to determine the prevalence and subtype distribution of Blastocystis and its relation with demographic data and symptoms in humans referred to medical centers in Ahvaz 2014-2015. BACKGROUND: Infections with intestinal parasites are one of the most important threats to human health worldwide, especially in tropical and subtropical areas. Blastocystis sp. is a common parasite of humans with a vast variety of non-human hosts. We aimed to study the prevalence and subtypes of Blastocystis sp. in individuals referred to medical laboratories in Ahvaz city, southwest Iran. METHODS: From September 2014 to September 2015, 618 stool samples were collected from 16 medical laboratories in Ahvaz, and examined using direct wet mount, formalin-ether concentration, a modified version of the Ziehl-Neelsen staining technique, and cultivation in xenic HSr + S medium. Subtypes of positive Blastocysts sp. were obtained using the "barcoding" method. The results were analyzed using SPSS software, version 16, with Chi-square and Fisher's exact test. RESULTS: Totally, 325 (52.6%) of the referred individuals were men and 293 (47.4%) were women. Blastocystis sp. was observed in 146 (23.6%) samples. Co-infections with other intestinal parasites were found in 32 (5.17%) cases. Out of the 146 positive isolates, 20.83%, 20.83% and 58.34% belonged to ST1, ST2, ST3 respectively. CONCLUSION: Blastocystis sp. was quite common in the study population, with a carrier rate corresponding to nearly one in every four individuals. The subtype distribution identified in the present study was largely identical to that reported from other studies in Iran, with ST3 being the most common.
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PURPOSE: Purulent or exudative genitourinary infections are a frequent cause of consultation in primary and specialized healthcare. The objectives of this study were: to determine the prevalence of Trichomonas vaginalis and co-infections with Candida spp. and Gardnerella vaginalis in vaginal secretion; and to use multilocus sequence typing (MLST) to analyse the genetic diversity of T. vaginalis strains. METHODOLOGY: The samples were submitted for analysis (n=5230) to a third-level hospital in Granada (Southern Spain) between 2011 and 2014; eight T. vaginalis strains isolated during 2015 were randomly selected for MLST analysis. Culture and nucleic acid hybridization techniques were used to detect microorganisms in the samples. RESULTS: The prevalence of T. vaginalis was 2.4â% between 2011 and 2014, being higher during the first few months of both 2011 and 2012. Among samples positive for T. vaginalis, co-infection with G. vaginalis was detected in 29 samples and co-infection with Candida spp. in 6, while co-infection with all three pathogens was observed in 3 samples. The only statistically significant between-year difference in co-infection rates was observed for T. vaginalis with G. vaginalis due to an elevated rate in 2011. MLST analysis results demonstrated a high genetic variability among strains circulating in our setting. CONCLUSION: These findings emphasize the need for the routine application of diagnostic procedures to avoid the spread of this sexually transmitted infection.
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Candida/clasificación , Candidiasis/complicaciones , Gardnerella vaginalis/aislamiento & purificación , Variación Genética , Tricomoniasis/microbiología , Trichomonas vaginalis/genética , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Candidiasis/epidemiología , Coinfección/epidemiología , Coinfección/microbiología , Coinfección/parasitología , Femenino , Infecciones por Bacterias Grampositivas/complicaciones , Infecciones por Bacterias Grampositivas/epidemiología , Infecciones por Bacterias Grampositivas/microbiología , Humanos , Persona de Mediana Edad , España/epidemiología , Tricomoniasis/complicaciones , Tricomoniasis/epidemiología , Enfermedades Vaginales/epidemiología , Enfermedades Vaginales/microbiología , Enfermedades Vaginales/parasitología , Adulto JovenRESUMEN
Ingestion of eggs (ova) of the porcine nematode parasite Trichuris suis (TSO) may reduce the severity of autoimmune disorders, however the development of TSO treatment as a useful therapy for autoimmune diseases is hampered by a lack of knowledge on the development of the parasite and the nature of the local immune responses in humans. Here, we used colonoscopy to investigate the development of T. suis and related mucosal and systemic immune responses during TSO treatment in an intestinally healthy male volunteer. TSO treatment induced T. suis-specific serum antibodies, a transient blood eosinophilia, and increases in IFNγ+ and IL4+ cells within the circulating CD4+ T-cell population. Increased expression of genes encoding cytokines (IL4, IL10, IL17 and TGF-ß), and transcription factors (FOXP3, GATA3 and RORC) were apparent in the ascending and transverse colon (the predilection site of the worms), whereas only limited changes in gene expression were observed proximally (ileum) and distally (descending colon) to the infected tissue. We further show that T. suis is able to colonise the human colon, with a number of worms developing to a similar size and morphology observed in the natural pig host, and a small number of unembryonated eggs were passed in the faeces, indicating patent infection. Notably, the volunteer experienced a substantial improvement in psoriasis during the course of TSO treatment. Thus, TSO treatment induced a mixed Th1/Th2/T regulatory response at the local site of infection, which was also reflected to some extent in the peripheral circulation. These results, together with the first definitive observations that T. suis can mature to adult size and reproduce in humans, shed new light on the interaction between the human immune system and probiotic helminth treatment, which should facilitate further development of this novel therapeutic option.
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Antígenos Helmínticos/inmunología , Óvulo/inmunología , Probióticos/administración & dosificación , Trichuris/inmunología , Adulto , Animales , Femenino , Voluntarios Sanos , Humanos , Inmunidad , Masculino , Psoriasis/diagnóstico , Psoriasis/inmunología , Psoriasis/terapia , Índice de Severidad de la Enfermedad , Porcinos , Enfermedades de los Porcinos/inmunología , Enfermedades de los Porcinos/parasitología , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/metabolismoRESUMEN
Blastocystis is an intestinal parasite that is very easily isolated in culture from fresh stool samples. In fact, the parasite grows so readily in culture that short-term in vitro culture is sometimes used as a diagnostic tool in the absence of DNA-based methods. While axenizing Blastocystis cultures remains a significant challenge, the parasite can be propagated for several months in the presence of metabolically active bacteria (xenic culture). Hence, culture can be used for maintaining live Blastocystis strain libraries. This enables the production of a stable resource of reference material, which for instance can be used for DNA-based assays and research. Blastocystis isolates can also be cryopreserved with a view to reestablishing them in culture. Here, we provide protocols for xenic in vitro culture and cryopreservation of Blastocystis. © 2016 by John Wiley & Sons, Inc.
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Blastocystis/crecimiento & desarrollo , Técnicas de Cultivo de Célula/métodos , Criopreservación/métodos , Blastocystis/genética , Blastocystis/aislamiento & purificación , Blastocystis/metabolismo , Infecciones por Blastocystis/parasitología , Medios de Cultivo/química , Medios de Cultivo/metabolismo , HumanosRESUMEN
Several typing methods have been used in studies aiming to unravel the molecular epidemiology of Blastocystis, which is one of the most common intestinal parasites in human and many non-human hosts. Such studies have the potential to add to knowledge on Blastocystis transmission, host specificity, phylogeography, and clinical and public health significance, but rely on robust, standardized methods by which data can be generated and compared directly between studies. One of the most used methods is "barcoding,", which involves single-round PCR amplification and sequencing of partial small subunit ribosomal RNA genes of the parasites. Recently, a publicly available online facility was developed for quick and standardized identification of subtypes (ribosomal lineages) and subtype alleles (variation within subtypes) based on sequence data obtained by barcoding PCR. Moreover, a modified barcoding approach is now available using nested PCR, which enables detection of mixed subtype infections. © 2016 by John Wiley & Sons, Inc.
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Infecciones por Blastocystis/parasitología , Blastocystis/genética , Blastocystis/aislamiento & purificación , Técnicas de Cultivo de Célula/métodos , Reacción en Cadena de la Polimerasa/métodos , Análisis de Secuencia de ADN/métodos , Blastocystis/metabolismo , Medios de Cultivo/química , Medios de Cultivo/metabolismo , ADN Protozoario/genética , ADN Protozoario/aislamiento & purificación , Heces/parasitología , Genotipo , HumanosRESUMEN
Complete mitochondrion-related organelle (MRO) genomes of several subtypes (STs) of the unicellular stramenopile Blastocystis are presented. Complete conservation of gene content and synteny in gene order is observed across all MRO genomes, comprising 27 protein coding genes, 2 ribosomal RNA genes, and 16 transfer RNA (tRNA) genes. Despite the synteny, differences in the degree of overlap between genes were observed between subtypes and also between isolates within the same subtype. Other notable features include unusual base-pairing mismatches in the predicted secondary structures of some tRNAs. Intriguingly, the rps4 gene in some MRO genomes is missing a start codon and, based on phylogenetic relationships among STs, this loss has happened twice independently. One unidentified open reading frame (orf160) is present in all MRO genomes. However, with the exception of ST4 where the feature has been lost secondarily, orf160 contains variously one or two in-frame stop codons. The overall evidence suggests that both the orf160 and rps4 genes are functional in all STs, but how they are expressed remains unclear.
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Codón Iniciador/genética , Codón de Terminación/genética , Evolución Molecular , Genoma Mitocondrial/genética , Estramenopilos/genética , Emparejamiento Base , Anotación de Secuencia Molecular , Sistemas de Lectura Abierta , Filogenia , ARN Ribosómico/genética , ARN de Transferencia/genética , Estramenopilos/clasificaciónRESUMEN
Despite Blastocystis being one of the most widespread and prevalent intestinal eukaryotes, its role in health and disease remains elusive. DNA-based detection methods have led to a recognition that the organism is much more common than previously thought, at least in some geographic regions and some groups of individuals. Molecular methods have also enabled us to start categorizing the vast genetic heterogeneity that exists among Blastocystis isolates, wherein the key to potential differences in the clinical outcome of Blastocystis carriage may lie. In this review we summarize some of the recent developments and advances in Blastocystis research, including updates on diagnostic methods, molecular epidemiology, genetic diversity, host specificity, clinical significance, taxonomy, and genomics. As we are now in the microbiome era, we also review some of the steps taken towards understanding the place of Blastocystis in the intestinal microbiota.
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Infecciones por Blastocystis , Blastocystis , Investigación/tendencias , Animales , Blastocystis/clasificación , Blastocystis/genética , Infecciones por Blastocystis/diagnóstico , Infecciones por Blastocystis/epidemiología , Infecciones por Blastocystis/terapia , Variación Genética , Genoma de Protozoos/genética , Especificidad del Huésped , HumanosRESUMEN
Over the past few decades, nucleic acid-based methods have been developed for the diagnosis of intestinal parasitic infections. Advantages of nucleic acid-based methods are numerous; typically, these include increased sensitivity and specificity and simpler standardization of diagnostic procedures. DNA samples can also be stored and used for genetic characterization and molecular typing, providing a valuable tool for surveys and surveillance studies. A variety of technologies have been applied, and some specific and general pitfalls and limitations have been identified. This review provides an overview of the multitude of methods that have been reported for the detection of intestinal parasites and offers some guidance in applying these methods in the clinical laboratory and in epidemiological studies.
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Parasitosis Intestinales/diagnóstico , Parasitosis Intestinales/epidemiología , Técnicas de Diagnóstico Molecular/métodos , Parásitos/aislamiento & purificación , Parasitología/métodos , Animales , Humanos , Epidemiología Molecular/métodos , Parásitos/clasificaciónRESUMEN
Recently, conflicting evidence has been published on the mode of transmission of the trichomonad Dientamoeba fragilis. Detection of D. fragilis DNA inside Enterobius vermicularis eggs agrees with the prediction of Dobell in 1940 that the eggs of a nematode act as a vector for transmission. However, the identification of a cyst stage of D. fragilis in the stool of rodents infected with a human isolate has also been reported, and this implies a life cycle similar to those of most other intestinal protistan parasites. Herein we discuss the recent data, identify gaps in the experimental evidence, and propose a method for determining which view of the life cycle of this organism is correct.
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Dientamoeba/parasitología , Dientamebiasis/transmisión , Vectores de Enfermedades , Enterobius/parasitología , Animales , Heces/parasitología , Humanos , Estadios del Ciclo de Vida/fisiología , Roedores/parasitologíaRESUMEN
Blastocystis is a common unicellular anaerobic eukaryote that inhabits the large intestine of many animals worldwide, including humans. The finding of Blastocystis in faeces in mammals and birds has led to proposals of zoonotic potential and that these hosts may be the source of many human infections. Blastocystis is, however, a genetically diverse complex of many distinct organisms (termed subtypes; STs), and sampling to date has been limited, both geographically and in the range of hosts studied. In order to expand our understanding of host specificity of Blastocystis STs, 557 samples were examined from various non-primate animal hosts and from a variety of different countries in Africa, Asia and Europe. STs were identified using 'barcoding' of the small subunit rRNA gene using DNA extracted either from culture or directly from faeces. The host and geographic range of several STs has thereby been greatly expanded and the evidence suggests that livestock is not a major contributor to human infection. Two new STs were detected among the barcode sequences obtained; for these, and for three others where the data were incomplete, the corresponding genes were fully sequenced and phylogenetic analysis was undertaken.
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Animales de Zoológico/parasitología , Blastocystis/genética , Blastocystis/aislamiento & purificación , Reservorios de Enfermedades/parasitología , Variación Genética , Ganado/parasitología , Animales , Blastocystis/clasificación , Blastocystis/fisiología , Especificidad del Huésped , Humanos , Datos de Secuencia Molecular , FilogeniaRESUMEN
Blastocystis is a common parasite of the human large intestine but has an uncertain role in disease. In this review, we appraise the published evidence addressing this and its weaknesses. Genetic diversity studies have led to the identification of numerous subtypes (STs) within the genus Blastocystis and, recently, methods for studying variation within STs have been developed, with implications for our understanding of host specificity. The geographic distribution of STs is summarised and the impact this may have on investigations into the role of the organism in disease is discussed. Finally, we describe the organelle and nuclear genome characteristics and look to future developments in the field.
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Infecciones por Blastocystis/parasitología , Blastocystis/fisiología , Blastocystis/clasificación , Blastocystis/genética , Blastocystis/patogenicidad , Infecciones por Blastocystis/epidemiología , Variación Genética , Genoma de Protozoos , Humanos , Filogeografía , Prevalencia , Topografía MédicaRESUMEN
Blastocystis SSU-rDNA sequence data from 317 captive and free-living non-human primates (NHPs) representing 30 genera of apes, Old and New World (OW and NW) monkeys and prosimians were analysed to investigate subtype (ST) and allele distribution among hosts. Excluding 20 mixed ST infections, 27% of the sequences belonged to ST1, 22% to ST2, 34% to ST3, 1% to ST4, 4% to ST5, 11% to ST8, <1% to ST13 and 1% to ST15. The study confirmed cryptic host specificity of ST1 and ST3; conversely, considerable overlap in ST2 alleles exists among humans and NHPs. Subtype distribution in humans and NHPs differs mainly in that ST4 is rarely reported in NHPs while ST5 and ST8 are both unusual in humans. This may be due to host specificity and/or the apparent geographically restricted range of some subtypes. While the distribution of ST1, ST2 and ST3 was independent of NHP group or geographical association, ST5 was seen only in apes and OW monkeys and ST8 primarily in arboreal NHPs and only in species native to Asia or South America.
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Infecciones por Blastocystis/veterinaria , Blastocystis/aislamiento & purificación , Variación Genética , Enfermedades de los Primates/epidemiología , Enfermedades de los Primates/parasitología , Alelos , Animales , Blastocystis/clasificación , Blastocystis/genética , Infecciones por Blastocystis/epidemiología , Infecciones por Blastocystis/parasitología , ADN Protozoario/química , ADN Protozoario/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Heces/parasitología , Genotipo , Haplorrinos , Especificidad del Huésped , Filogenia , Primates , ARN Ribosómico 18S/genética , Análisis de Secuencia de ADN , StrepsirhiniRESUMEN
Blastocystis is a common intestinal micro-eukaryote found in both humans and non-human hosts and known to be genetically very diverse. It has been divided into numerous subtypes (STs), nine of which have been identified in humans to date. Surveys of ST prevalence have started to emerge over the past few years but to date no data are available for any African country except Egypt and Tanzania. In this study, we determined the prevalence of Blastocystis STs in populations from Libya, Liberia and Nigeria, as well as expanding the dataset available for the UK. A total of 356 Blastocystis STs were identified in this study, 271 from the UK, 38 from Libya, 25 from Liberia and 22 from Nigeria. SSU rRNA gene sequences revealed the presence of eight of the nine STs known from humans but at varying frequencies between countries. ST1 was the most common ST in Libya and Nigeria whereas ST3 showed the highest frequency in the other two countries, as indeed is the case in most populations around the world. ST4 was absent in Libya and ST2 in Nigeria, while no ST5, ST6, ST8 or ST9 infections were detected in any of the three African populations. The picture emerging from this and other surveys suggests that there is significant variation in ST prevalence between populations. Some of the possible reasons for and implications of this diversity are discussed.