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Trends in Parasitology Mar 2020
Review
Topics: Animals; Blastocystis; Blastocystis Infections; Humans
PubMed: 32001134
DOI: 10.1016/j.pt.2019.12.008 -
Research in Veterinary Science Mar 2021Blastocystis is a ubiquitous parasite that infects a broad range of vertebrate hosts including humans and domestic and wild animals. While human infections have been... (Review)
Review
Blastocystis is a ubiquitous parasite that infects a broad range of vertebrate hosts including humans and domestic and wild animals. While human infections have been occasionally associated with gastrointestinal illnesses and/or urticaria, animal infections are not usually associated with disease. However, from a public health perspective, most subtypes isolated in humans have also been isolated from animals raising the question of the importance of animal reservoirs in the epidemiology of this parasite. The identification of Blastocystis in water supplies suggests water can be a potential vehicle in the transmission of this parasite not only for humans but also for animals. In addition, Blastocystis has been detected in retail fresh produce. Knowledge of this parasite has greatly expanded in the last two decades from simple microscopic observations to the application of molecular tools to explore Blastocystis taxonomy and epidemiology. This review provides a comprehensive overview of Blastocystis in animals highlighting the subtype diversity of this widespread and genetically diverse parasite in different animal groups. This information will be useful in understanding the current status of taxonomy, epidemiology, zoonotic potential, and public health importance of Blastocystis.
Topics: Animals; Animals, Domestic; Birds; Blastocystis; Blastocystis Infections; Feces; Genetic Variation; Humans; Mammals
PubMed: 33046256
DOI: 10.1016/j.rvsc.2020.09.031 -
Acta Parasitologica Sep 2022The present review was done to evaluate the prevalence and subtype distribution of Blastocystis infection among small ruminants, at a global perspective. (Meta-Analysis)
Meta-Analysis Review
PURPOSE
The present review was done to evaluate the prevalence and subtype distribution of Blastocystis infection among small ruminants, at a global perspective.
METHODS
Systematic search was performed in PubMed, Scopus, Google Scholar, and Web of Science until 30th January 2022 and total estimates along with 95% confidence intervals (CIs) were computed using a random-effects model.
RESULTS
Ultimately, the required data were extracted from 25 papers including 19 datasets for each animal. Among 3125 sheep, the Blastocystis prevalence was 25.3% (95% CI 16.1-37.4%) (10 countries), being lower in comparison to that in 2869 examined goats [20.5% (95% CI 11-35.1%)] (12 countries). Regarding STs distribution, fourteen genetically diverse STs of Blastocystis (ST1-ST5, ST7, ST10, ST12, ST14, ST15, ST21, ST23, ST24, ST26) have been reported in sheep, and the highest pooled prevalence was related to ST10 [11 datasets, 57.8% (95% CI 43.7-70.8%)], followed by ST14 [8 datasets, 28.4% (95% CI 20.2-38.4%)], and ST7 [2 datasets, 21.1% (95% CI 4.5-60.3%)]. Compared to sheep, more STs (ST1, ST3-ST7, ST10, ST12, ST14, ST21, ST23-ST26, and ST32) were reported from goats, and the highest weighted frequency was related to ST10 [6 datasets, 45.1% (95% CI: 25.6-66.2%)], followed by ST7 [2 datasets, 40.4% (95% CI 30-51.7%)], and ST14 [4 datasets, 29% (95% CI 15.5-47.7%)]. Out of ten known zoonotic STs reported for Blastocystis (ST1-ST9, and ST12), 7 were isolated from sheep (ST1-ST5, ST7, and ST12) and 7 were reported from goats (ST1, ST3-ST7, ST12).
CONCLUSIONS
Overall, Blastocystis epidemiology in sheep and goats is yet to be elucidated and demands more comprehensive studies.
Topics: Animals; Blastocystis; Blastocystis Infections; Feces; Genetic Variation; Goats; Phylogeny; Prevalence; Sheep
PubMed: 35834160
DOI: 10.1007/s11686-022-00589-3 -
Turkiye Parazitolojii Dergisi Sep 2023is an anaerobic protozoan with global importance because of infecting a variety of hosts and having high prevalence in many countries. isolates display remarkable... (Review)
Review
is an anaerobic protozoan with global importance because of infecting a variety of hosts and having high prevalence in many countries. isolates display remarkable genetic differences, and many subtypes (STs) have currently been defined based on polymorphism in coding gene. Each 25 subtype may have different characteristics such as pathogenicity, host specificity, and structural variations. Most current research on has focused on these differences and molecular epidemiology. This review aimed to provide a summary of subtype distribution in Türkiye. Regarding human samples, 16 manuscripts were found in the literature, which presented 783 isolates from 9 cities in Türkiye. The most common subtype was ST3 (47.9%), the others were ST1 30 (17.5%), ST2 (14.7%), ST4 (4%), and ST5-ST7 (15.9%). There were few studies on animal hosts and environmental samples. The faecal samples from rats, farm, and pet animals were examined for subtypes and ST1, ST3, ST4-ST7, ST10, and ST12-ST14 were reported. In addition, two studies reported ST1 and ST3 subtypes in environmental water samples. In conclusion, the review of available literature showed that a systematic understanding of the subtype distribution of 35 in Türkiye is still lacking. Most of the studies were performed in a limited number of cities, animal hosts, and environmental samples, therefore, more studies from different provinces are needed in forthcoming research. The majority studies were performed in a limited number of provinces, animal species and very few environmental samples, so in the future; there is a need of novel studies that evaluate more samples from different provinces.
Topics: Humans; Animals; Rats; Blastocystis; Cities; Feces; Polymorphism, Genetic
PubMed: 37724369
DOI: 10.4274/tpd.galenos.2023.79188 -
Parasitology International Dec 2016Blastocystis is a common unicellular eukaryotic parasite found not only in humans, but also in various kinds of animal species worldwide. Since Blastocystis isolates are... (Review)
Review
Blastocystis is a common unicellular eukaryotic parasite found not only in humans, but also in various kinds of animal species worldwide. Since Blastocystis isolates are morphologically indistinguishable, many molecular biological approaches have been applied to classify these isolates. The complete or partial sequences of the small subunit rRNA gene (SSU rDNA) are mainly used for comparisons and phylogenetic analyses among Blastocystis isolates. However, various lengths of the partial SSU rDNA sequence have been used for phylogenetic inference among genetically different isolates. Based on the complete SSU rDNA sequences, consensus terminology of nine subtypes (STs) of Blastocystis sp. that were supported by phylogenetically monophyletic nine clades was proposed in 2007. Thereafter, eight additional kinds of STs comprising non-human mammalian Blastocystis isolates have been reported based on the phylogeny of SSU rDNA sequences, while STs 11 and 12 were only proposed on the base of partial sequences. Although many sequence data from mammalian and avian Blastocystis are registered in GenBank, only limited data on SSU rDNA are available for poikilotherm-derived Blastocystis isolates. Therefore, the phylogenetic positions of the reptilian/amphibian Blastocystis clades are unstable. The phylogenetic inference of various STs comprising mammalian and/or avian Blastocystis isolates was verified herein based on comparisons between partial and complete SSU rDNA sequences, and the phylogenetic positions of reptilian and amphibian Blastocystis isolates were also investigated using 14 new Blastocystis isolates from reptiles with all known isolates from other reptilians, amphibians, and insects registered in GenBank.
Topics: Animals; Blastocystis; DNA, Protozoan; DNA, Ribosomal; Databases, Nucleic Acid; Humans; Insecta; Phylogeny
PubMed: 27091546
DOI: 10.1016/j.parint.2016.04.004 -
Infection, Genetics and Evolution :... Nov 2021Blastocystis is a commonly encountered gastrointestinal protozoan in humans and animals with uncertain pathogenicity. Despite its potential public health impact,... (Review)
Review
Blastocystis is a commonly encountered gastrointestinal protozoan in humans and animals with uncertain pathogenicity. Despite its potential public health impact, epidemiological data regarding the prevalence and molecular subtype (ST) distribution of Blastocystis have been rarely reported. Among Blastocystis STs, ST1-ST4 are common in humans, including healthy and immunodeficient populations. According to the Chi-squared (χ) association based on the data compiled for this cross-sectional study, the presence of ST1 is associated with asymptomatic infection, whereas the presence of ST4 is associated with symptomatic infection. However, cross-sectional studies cannot clarify the potential pathogenicity of Blastocystis, unlike in vivo and in vitro studies. Poor hygiene, poor sanitation and zoonotic transmission are possible factors associated with high Blastocystis prevalence, although this protozoan may be part of the normal healthy human gastrointestinal microbiota. This review covers the prevalence, STs and distribution of Blastocystis infection in humans. Thus, future epidemiological and subtyping studies could reveal new STs in humans as well as possible associations of STs with disease, drug resistance and related mechanisms such as protease activity. These associations with proper ST identification may facilitate the control of potential threats to host health, including the direct pathogenic effects of Blastocystis or alterations of the gastrointestinal microbiome.
Topics: Blastocystis; Blastocystis Infections; Humans; Prevalence
PubMed: 34530156
DOI: 10.1016/j.meegid.2021.105085 -
Parasites & Vectors Jul 2019Blastocystis is a stramenopile of worldwide significance due to its capacity to colonize several hosts. Based on its high level of genetic diversity, Blastocystis is... (Review)
Review
BACKGROUND
Blastocystis is a stramenopile of worldwide significance due to its capacity to colonize several hosts. Based on its high level of genetic diversity, Blastocystis is classified into global ribosomal subtypes (STs). The aim of this study was to conduct a summary of Blastocystis STs and depict their distribution throughout North and South America; we did this by assembling maps and identifying its most common 18S alleles based on diverse studies that had been reported all over the continent and whose Blastocystis-positive samples were obtained from numerous hosts.
RESULTS
Thirty-nine articles relating to nine countries from the American continent were considered, revealing that ST1 (33.3%), ST2 (21.9%), ST3 (37.9%), ST4 (1.7%), ST5 (0.4%), ST6 (1.2%), ST7 (1%), ST8 (0.7%), ST9 (0.4%), ST12 (0.3%), Novel ST (1.1%) and Mixed STs (0.2%) occurred in humans. The STs in other animal hosts were ST1 (6.5%), ST2 (6.5%), ST3 (4.7%), ST4 (7.2%), ST5 (15.9%), ST6 (17.3%), ST7 (3.6%), ST8 (20.6%), ST10 (9%), ST14 (3.6%), ST17 (1.1%) and Novel ST (4%). The countries that presented the most abundant variety of studies reporting STs were the USA with 14 STs, Brazil with 9 STs and Colombia with 8 STs. Additionally, new variants had been described in the last few years, which have increased the prevalence of these subtypes in the countries studied, such as Novel ST (1.1%) and Mixed STs (0.2%) in humans and Novel ST (4%) in animals.
CONCLUSIONS
This summary updates the epidemiological situation on the distribution of Blastocystis STs in North and South America and will augment current knowledge on the prevalence and genetic diversity of this protozoan.
Topics: Alleles; Animals; Blastocystis; Blastocystis Infections; DNA, Protozoan; DNA, Ribosomal; Feces; Genetic Variation; Genotype; Humans; North America; Phylogeny; Prevalence; RNA, Ribosomal, 18S; South America
PubMed: 31358042
DOI: 10.1186/s13071-019-3641-2 -
Clinical Microbiology Reviews Oct 1996Blastocystis hominis is a unicellular organism found commonly in the intestinal tract of humans and many other animals. Very little is known of the basic biology of the... (Review)
Review
Blastocystis hominis is a unicellular organism found commonly in the intestinal tract of humans and many other animals. Very little is known of the basic biology of the organism, and controversy surrounds its taxonomy and pathogenicity. There morphological forms (vacuolar, granular, and ameboid) have been recognized, but recent studies have revealed several additional forms (cyst, avacuolar, and multivacuolar). The biochemistry of the organism has not been studied to any extent, and organelles and structures of unknown function and composition are present in the cells. Several life cycles have been proposed but not experimentally validated. The form used for transmission has not been defined. Infections with the organism are worldwide and appear in both immunocompetent and immunodeficient individuals. Symptoms generally attributed to B. hominis infection are nonspecific, and the need for treatment is debated. If treatment appears warranted, metronidazole is suggested as the drug of choice, although failures of this drug in eradicating the organism have been reported. Infection is diagnosed by light microscopic examination of stained smears or wet mounts of fecal material. Most laboratories identify B. hominis by observing the vacuolar form, although morphological studies indicate that other forms, such as the cyst form and multivacuolar form, also should be sought for diagnosis.
Topics: Animals; Antiprotozoal Agents; Blastocystis Infections; Blastocystis hominis; Disease Transmission, Infectious; Drug Therapy, Combination; Humans; Microscopy, Electron; Prevalence
PubMed: 8894352
DOI: 10.1128/CMR.9.4.563 -
Medical Hypotheses Jul 2018Blastocystis spp. is a common intestinal protozoan that affects humans and animals. The role of this parasite as a pathogen is still controversial and it is suspected to... (Review)
Review
Blastocystis spp. is a common intestinal protozoan that affects humans and animals. The role of this parasite as a pathogen is still controversial and it is suspected to be linked to Irritable Bowel Syndrome (IBS), a functional bowel disorder characterized by chronic or recurrent abdominal pain associated with altered intestinal habits. A broad search in electronic databases, libraries, portals of journals, etc. for reports on the association between the parasite and IBS without language restriction was performed. The selection was not restricted by date, but articles published in the last seven years were given preference. We investigated the evidence regarding Blastocystis and IBS coexistence as well as the implications of the parasite in pathogenesis and clinical manifestations. Only standardized parasitological tools, supplemented by epidemiological analysis, will be able to clarify whether parasite carriage could be connected to IBS and its status as a human pathogen. Although a variation in pathogenicity and virulence between subtypes has been confirmed, Blastocystis can only be considered an indicator of dysbiosis. Accurate diagnoses of this parasitic eukaryote, specifically at genotypic and phenotypic levels, as well as the complete analysis of the intestinal microbial communities, have to be included in the protocol of those patients with IBS.
Topics: Animals; Blastocystis; Blastocystis Infections; Genomics; Genotype; Humans; Irritable Bowel Syndrome; Models, Theoretical; Phenotype; Polymerase Chain Reaction
PubMed: 29857906
DOI: 10.1016/j.mehy.2018.04.006 -
Trends in Parasitology Mar 2020Blastocystis is a genetically diverse intestinal protist colonizing both human and non-human hosts. By 2013, 17 subtypes had been acknowledged. Since then, nine more... (Review)
Review
Blastocystis is a genetically diverse intestinal protist colonizing both human and non-human hosts. By 2013, 17 subtypes had been acknowledged. Since then, nine more subtypes have been proposed. We argue that several recently proposed subtypes are invalid. We also revisit recommendations regarding the requirements for annotating sequences as new subtypes.
Topics: Animals; Blastocystis; DNA, Protozoan; Humans; Molecular Sequence Annotation; Molecular Typing
PubMed: 32001133
DOI: 10.1016/j.pt.2019.12.009