Levels of genetic diversity vary dramatically between Blastocystis subtypes

New Haplotypes of Blastocystis sp. Identified in Faeces from Various Animal Groups in Algeria

PURPOSE

Blastocystis sp. is a single-celled, anaerobic, parasitic protozoan commonly found in the intestinal tract of animals and humans globally. Genetic analysis has revealed significant diversity within its species, leading to the identification of at least 40 subtypes (ST1-ST40). This study aimed to identify and differentiate Blastocystis in faeces samples from various animal hosts in Algeria.

METHODS

A total of 403 fecal samples, collected from both domestic and zoo animals, were subjected to PCR amplification and sequencing of Blastocystis-specific small subunit ribosomal RNA (SSU-RNA) gene.

RESULTS

The overall prevalence of Blastocystis in animals was found to be 38.9%. Through comprehensive phylogenetic and phylogeographic analyses, we identified four distinct subtypes (ST1 in both domestic and zoo animals, and ST3, ST4, and ST5 exclusively in zoo animals), encompassing nine different haplotypes, including five that appear original to Algeria.

CONCLUSION

This study represents the first epidemiological molecular investigation of Blastocystis sp. in animals in Algeria.

Subtype Distribution of Blastocystis spp. in Patients with Gastrointestinal Symptoms in Northern Spain

Limited molecular data exist on the prevalence and subtype distribution of Blastocystis spp., the most prevalent parasite in human and animal feces worldwide. A total of 44 different subtypes (STs) of Blastocystis are currently recognized based on the sequence of the small subunit ribosomal RNA (SSU-rRNA) gene. This is a molecular study of Blastocystis spp. in hospitalized patients with gastrointestinal symptoms in northern Spain. We analyzed 173 Blastocystis-positive patients with gastrointestinal symptoms by using nested PCR for molecular detection, subtype identification, phylogenetic analyses, and genetic diversity assessment. ST2 (34.1%) and ST3 (34.7%) predominated, followed by ST1 (15.6%) and ST4 (15.6%). Mixed infections with different subtypes were observed in some patients. Sequence analysis revealed for the first time in European humans the allele 88 (a variant of ST1). In other cases, alleles commonly found in animal samples were detected (allele 9 in ST2, allele 34 in ST3, and allele 42 in ST4). Phylogenetic analysis showed high variability in ST1 and ST2, suggesting a polyphyletic origin, while both ST3 and ST4 exhibited higher genetic homogeneity, indicating a possible monophyletic origin and recent transmission to humans. These data confirm Blastocystis spp. subtype diversity and may help in understanding the evolutionary processes and potential zoonotic transmission of this parasite.

Subtype-host patterns and genetic differentiation of Blastocystis sp. in the Philippines

Blastocystis sp. is a gastrointestinal protozoan commonly encountered in humans and animals. Specificity to certain hosts may be associated with 38 known subtypes (STs) and 8 nonmammalian and avian STs (NMASTs). This can be determined by analyzing ST-host associations, ST-allele data, genetic variability analyses, and fixation index (FST) with sufficient data present. Thus, newly acquired and previously published data on Blastocystis sp. STs and NMASTs from the Philippines were compiled to determine the following: (1) ST-host associations, (2) ST-allele diversity per ST in certain hosts/sources, (3) intrasubtype diversity of certain STs found in different hosts using genetic variability analysis, and (4) comparison of similarities between specific ST populations to determine if these are the same circulating populations using FST. A total of 448 samples subtyped using both sequence-tagged site primers and the 600-bp barcoding region of the Blastocystis sp. SSU rRNA gene were analyzed in this study. Patterns of association for the Philippine samples were similar to those from neighboring Southeast Asian countries and around the world: ST1-ST4 were found in humans but ST3 was the most common, ST5 were found in pigs, and ST6 and ST7 were found in poultry. Blastocystis sp. from humans are mostly the same ST alleles (ST3 allele 34 and ST1 allele 4) while 3-5 ST alleles were found in the most common STs in pigs, macaques, and poultry. Also, ST1, ST3, ST5, and NMAST I are undergoing population expansion according to genetic variability analyses through possible addition of new alleles based on ST-allele diversity. Moreover, FST shows the same circulating population of ST1 in humans, pigs, and water indicating a possible waterborne route of cross-transmission. In contrast, ST3 found in humans possibly come from the same circulating population and is genetically distinct from those in nonhuman sources.

Irritable Bowel Syndrome Associated with Blastocystis hominis or Without Relationship to It? A Case-Control Study and Minireview

BACKGROUND

Blastocystis hominis (B. hominis) is a protozoan parasite that has a worldwide distribution. Some studies have suggested a link between B. hominis and the development of irritable bowel syndrome (IBS). The objective of this study was to determine the prevalence of B. hominis in patients with IBS compared to healthy individuals.

MATERIAL AND METHODS

A total of 65 stool samples from patients with IBS and 65 samples from healthy individuals in northern Iran were examined. The samples were tested using various methods including direct smear, formalin ether sedimentation and culture to detect the presence of B. hominis. Additionally, polymerase chain reaction (PCR) was performed on all culture-positive isolates to confirm the results and identify the genotype.

RESULTS

B. hominis was detected in 15.38% of IBS patients and 9.2% of the healthy group. The culture in RPMI1640 was found to be better than the formalin ether and direct smear methods. Positive samples were confirmed using the molecular method. No significant difference was observed in the order of B. hominis infection between the two groups.

CONCLUSIONS

The results of our study indicate that no significant difference was observed in the order of B. hominis infection between IBS patients and healthy groups. Therefore, further study is necessary to determine the potential pathogenic effects of this parasite and its role in causing IBS.

Blastocystis genetic diversity in animal and human samples from different departments of Colombia using complete sequencing of the 18S rRNA gene (SSU rRNA) by Oxford Nanopore Technologies (ONT)

Blastocystis is an intestinal microeukaryote that has raised attention due to its wide distribution in animals and humans. The risk of zoonotic circulation primarily arises from close contact with infected animals. Therefore, the following study aimed to evaluate the diversity and frequency of Blastocystis subtypes in Colombian human and animal samples using complete sequencing of the 18S rRNA gene. For this purpose, 341 human stool samples and 277 animal fecal samples (from cattle, sheep, goat, pigs, cats, and dogs), were collected from different Colombian regions and analyzed using PCR-based detection and full-length 18S SSU rRNA gene Next-Generation Sequencing (NGS). Among the 618 samples from both hosts, humans and animals, the results revealed widespread Blastocystis frequency, with 48.09% (n = 164) in humans and 31.4% (n = 87) detection in animals. Dogs, cats, sheep, pigs, and wild animals tested positive, aligning with global prevalence patterns. Also, 29 human samples and 23 animal samples were sequenced using ONT technology from which 11 long-read unique sequences were generated and cluster with their compared reference sequences. The subtype distribution varied within hosts, detecting ST1 and ST3 in both human and animal samples. Subtypes ST5, ST10, ST14, ST15, ST21, ST24, ST25 and ST26 were limited to animals hosts, some of which are considered to have zoonotic potential. On the other hand, ST2 was found exclusively in human samples from Bolivar region. Mixed infections occurred in both animal and humans, 60.86% and 27.58% respectively. Moreover, to our knowledge, this is the first study in Colombia identifying ST15 in pigs and ST25 in sheep. The subtypes (STs) identified in this study indicate that certain animals may serve as reservoirs with the potential for zoonotic transmission. The identification of zoonotic subtypes highlights the use of Next Generation Sequencing as the depth and resolution of the sequences increases providing insights into STs of medical and veterinarian significance. It also reveals the coexistence of diverse subtypes among hosts. Further research is essential for understanding transmission dynamics, health implications, and detection strategies for Blastocystis occurrence in animals and humans, mainly associated to the role of animals as reservoirs and their close interaction with humans.

Genetic characteristics of Blastocystis sp. ST3 at the genome level in the Chinese population

The gut microbiota comprises the collective genomes of microbial symbionts and is composed of bacteria, fungi, viruses, and protists within the gastrointestinal tract of a host. Although the literature associated with gut microbiota is increasing, studies on eukaryotes in the human gut are just beginning to surface. Blastocystis is one of the most common intestinal parasites of humans and animals and is estimated to colonise more than 1 billion people on a global scale. However, the understanding of the genetic characteristics of Blastocystis subtype (ST) at the genome level and its relationship with other members of the gut microbiota is still limited. In this study, by surveying the prevalence and genome characteristics of Blastocystis sp. ST3 in a Chinese population (prevalence % = 6.09%), the association of Blastocystis sp. ST3 with region and time and the structure of the resident gut bacterial population was clarified. We identified novel sequences (50 mitochondrial and 41 genome sequences) and determined their genetic diversity amongst strains within Blastocystis sp. ST3 (4.14 SNPs/kb). Furthermore, we found that colonisation of Blastocystis was strongly associated with increased bacterial richness and higher abundance of several anaerobes. Finally, we performed time series sampling on two Blastocystis-positive individuals and confirmed that Blastocystis could exist continually in the human gut microbiota and persist for a long time, even for 4 years.

Identification and validation of novel Blastocystis subtype ST41 in a Colombian patient undergoing colorectal cancer screening

Blastocystis sp. is among the most frequent intestinal protists identified in humans globally. However, characterization of Blastocystis subtype diversity in humans is ongoing. We report here the identification of novel Blastocystis subtype ST41 in a Colombian patient undergoing colorectal cancer screening involving colonoscopy and fecal testing (microscopy, culture, PCR). The full-length ssu rRNA gene sequence of the protist was generated using MinION long-read sequencing technology. The validity of the novel subtype was confirmed via phylogenetic and pairwise distance analyses of the full-length ST41 sequence and all other valid subtypes. The study provides reference material essential for conducting subsequent experimental studies.

Prevalence, potential risk factors and genetic diversity of Blastocystis in ruminant livestock animals from Penang, Malaysia

Blastocystis is a unicellular, anaerobic protist inhabiting the intestinal tract of diverse animal hosts, including human. Information regarding Blastocystis in small ruminants, namely goats and sheep, is limited globally; thus, this study was carried out to investigate the distribution and determinants of Blastocystis in ruminant livestock animals from Penang, Malaysia. Fecal samples from 127 cattle, 149 goats, and 100 sheep were examined for Blastocystis by in vitro cultivation using modified Jones' medium, while DNA barcoding was used for subtyping. Overall, 23.1% (87/376) of animals screened were positive for Blastocystis sp. The prevalence of infection was significantly higher in goats than in cattle and sheep, while the female gender, semi-intensive farming system, and the Northeast Penang Island district were identified as potential risk factors for Blastocystis infection. Blastocystis sp. ST5, ST14, and ST25 were identified in cattle; ST5, ST10, ST13, and ST14 in goats; and ST4, ST5, ST14, and ST15 in sheep. ST5 and ST14 were found to be the most abundant and widespread subtypes in the study area. To the best of our knowledge, this is the first report of ST4 from sheep and ST13 from goats, thus serving as an update to the host range of Blastocystis sp. ST4 and ST13. The isolation of ST4 and ST5 in this study suggests that ruminant livestock animals could serve as reservoirs of human infection.

Distribution of Blastocystis subtypes isolated from various animal hosts in Thailand

Blastocystis is a parasitic protist of a variety of hosts, including humans. Mapping the distribution of Blastocystis and its genetic variants across different host species can help us understand the epidemiology of this organism and its role in health and disease. This study aimed to identify subtypes of Blastocystis detected in different animal hosts in Thailand. A total of 825 fecal samples belonging to 18 vertebrate orders, 36 families, 68 genera, and 80 species were collected. Of these, 111 specimens were Blastocystis-positive by culture. Seventy-nine samples were subjected to small subunit (SSU) ribosomal DNA amplification by PCR, and reliable subtype data were obtained for 61 specimens. At least 14 subtypes (ST), namely ST1 to ST10, ST14/ST24/ST25 complex, ST23, ST26, and ST29 were detected. In addition, Blastocystis was found in tortoises. ST1 (3.2%) and ST5 (11.5%) were found in pigs, ST2 (1.6%) and ST3 (3.2%) in non-human primates, ST4 (14.7%) in rodents and ruminants, ST6 (4.9%), ST7 (30%), ST9 (1.6%), and ST29 (1.6%) in birds, ST8 (6.6%) in Green peafowl and East Asian Porcupine, and ST10 (4.9%), ST14/ST24/ST25 (9.8%), ST23 (1.6%) and ST26 (1.6%) in ruminants. The sequence recovered from the elongated tortoises (Indotestudo elongata) (3.2%) was phylogenetically placed within the reptilian cluster of Blastocystis, for which no subtype system is available yet. Of note, we did not obtain Blastocystis sequences from any of the many canids and felids sampled in the study, and our data are in support of host specificity of Blastocystis, according to both colonization and subtype distribution.

Epidemiology of Blastocystis Infection: A Review of Data from Poland in Relation to Other Reports

Blastocystis is a common gut protist of humans and various animals worldwide, with a high level of genetic diversity. Neither its zoonotic potential and transmission routes nor its pathogenicity are fully known. This fact, and the fact that Blastocystis is the most abundant eukaryote in human faeces, raises the question of its relevance to public health. Here, we summarise (in relation to other reports) the results of studies on the prevalence and genotypic variation of Blastocystis, which were carried out in animals, humans, and in water environments in Poland. In humans, the prevalence ranged between 0.14 and 23.6%, in some animals reached 58.97%, and in water environments was 5.1%. Seven subtypes were identified in humans (ST1-ST4, ST6, ST7, and ST9), of which ST3 was the most common. Among animals (wild, livestock, and pet animals), eleven STs were identified, with differential host specificity. Humans and animals shared ST1, ST2, ST3, ST6, and ST7, while ST1 and ST3 were present in humans, animals, and water sources. These observations indicate the possibility of Blastocystis transmission between animals and humans. Further studies should be continued in search of the sources and transmission routes of Blastocystis in order to prevent the spread of infections among humans and animals.

The eukaryome of African children is influenced by geographic location, gut biogeography, and nutritional status

Eukaryotes have historically been studied as parasites, but recent evidence suggests they may be indicators of a healthy gut ecosystem. Here, we describe the eukaryome along the gastrointestinal tract of children aged 2-5 years and test for associations with clinical factors such as anaemia, intestinal inflammation, chronic undernutrition, and age. Children were enrolled from December 2016 to May 2018 in Bangui, Central African Republic and Antananarivo, Madagascar. We analyzed a total of 1104 samples representing 212 gastric, 187 duodenal, and 705 fecal samples using a metabarcoding approach targeting the full ITS2 region for fungi, and the V4 hypervariable region of the 18S rRNA gene for the overall eukaryome. Roughly, half of all fecal samples showed microeukaryotic reads. We find high intersubject variability, only a handful of taxa that are likely residents of the gastrointestinal tract, and frequent co-occurrence of eukaryotes within an individual. We also find that the eukaryome differs between the stomach, duodenum, and feces and is strongly influenced by country of origin. Our data show trends towards higher levels of Fusarium equiseti, a mycotoxin producing fungus, and lower levels of the protist Blastocystis in stunted children compared to nonstunted controls. Overall, the eukaryome is poorly correlated with clinical variables. Our study is of one of the largest cohorts analyzing the human intestinal eukaryome to date and the first to compare the eukaryome across different compartments of the gastrointestinal tract. Our results highlight the importance of studying populations across the world to uncover common features of the eukaryome in health.

Molecular identification and genotyping of Blastocystis sp. in sheep and goats from some areas in Inner Mongolia, Northern China

Blastocystis sp. is a kind of unicellular intestinal commensal which is widely distributed in humans and animals, and frequently found in the people who are in close contact with animals. To investigate the prevalence and evaluate the zoonotic potential of Blastocystis sp. in sheep and goats from Inner Mongolia, China, a total of 1037 samples were collected from them, and subjected to nested PCR amplification based on the small subunit ribosomal RNA (SSU rRNA) gene of Blastocystis sp. The sanger sequencing was used for Blastocystis sp. subtype identification. The results indicated that the average infection rate of Blastocystis sp. was 10.70% [95CI: 8.82%-12.58%] (111/1037), including 11.30% [95CI: 7.96%-14.64%] for sheep (39/345) and 10.40% [95CI: 8.13%-12.67%] for goats (72/692). Five Blastocystis subtypes (ST5, ST10, ST14, ST21 and ST26) were identified in the present study. Among them, ST10 was the most dominant subtype in sheep and goats, accounting for 70.27% (78/111) of the total identified positive samples. This is the first report regarding Blastocystis sp. subtypes ST21 and ST26 in goats in China. This study has provided a detail epidemiological data on the prevalence and subtypes distribution of Blastocystis sp. in sheep and goats in Inner Mongolia, China. Our results indicated that sheep and goats could be reservoir host for multiple Bastocystis subtypes, including the zoonotic subtypes. Further studies among humans, livestock and wild animals are needed to better understand their role in the spread of Blastocystis sp.

Prevalence and Molecular Characterisation of Blastocystis sp. Infecting Free-Ranging Primates in Colombia

Infection with Blastocystis sp. has been reported in free-living and captive non-human primates (NHPs); however, surveys on Blastocystis sp. from north-western South America are scarce. This study aimed to identify Blastocystis sp. in free-ranging NHPs living in Colombia. A total of 212 faecal samples were collected from Ateles hybridus, Cebus versicolor, Alouatta seniculus, Aotus griseimembra, Sapajus apella, and Saimiri cassiquiarensis. Smears and flotation were used for morphological identification. For samples microscopically classified as positive for Blastocystis sp., we used conventional PCR to amplify and sequence two regions of the SSU rRNA gene and used Maximum Likelihood methods and Median Joining Network analyses for phylogenetic analyses. Via microscopy, 64 samples were Blastocystis sp. positive. Through molecular analyses, 18 sequences of Blastocystis sp. subtype 8 (ST8) were obtained. Strain and allele assignment together with a comparative phylogenetic approach confirmed that the sequences were ST8. Alleles 21, 156, and 157 were detected. Median Joining network analyses showed one highly frequent haplotype shared by specimens from Colombia and Peru and close relationships between haplotypes circulating in NHPs from Colombia, Ecuador, Brazil, and Mexico. This survey could support the elaboration of a more accurate epidemiological picture of the Blastocystis sp. infecting NHPs.

Extensive prevalence and significant genetic differentiation of Blastocystis in high- and low-altitude populations of wild rhesus macaques in China

BACKGROUND

Blastocystis is a common intestinal protist with a wide range of hosts. Thus far, 38 subtypes have been identified. In recent years, wild animals have been confronted with habitat fragmentation as well as an increasing risk of zoonotic disease transmission due to human disturbance. Only limited data are available on Blastocystis infection and subtype distribution in wild rhesus macaques in China. The aim of the present study was to investigate the prevalence and genetic diversity of Blastocystis in nine wild rhesus macaque populations in China.

METHODS

A total of 276 faecal samples were collected from five high-altitude populations (high-altitude group [HAG]; 2800-4100 m a.s.l.) and four low-altitude populations (low-altitude group [LAG]; 5-1000 m a.s.l) of rhesus macaques. PCR-based analysis, using a new primer pair for the amplification of a 1690-bp sequence of the small subunit ribosomal RNA (SSU rRNA) gene, was used for prevalence and genetic diversity analysis.

RESULT

Analysis of faecal samples revealed that Blastocystis infection was common in rhesus macaques, with an infection positivity rate of 80.1% (n = 221/276 samples). There was no significant difference (P = 0.121) in positivity rate between the LAG (84.3%) and HAG (76.8%). Overall, 33 haplotypes were obtained and classified into four subtypes (STs), of which three were potentially zoonotic subtypes (ST1, 29.7%; ST2, 16.7%; ST3, 31.9%) and one that was first identified in this study and named ST39 (12.0%). The STs were distributed differently among the rhesus macaque populations, except for ST3, which was found in all populations. Phylogenetic analyses revealed two major divergent clades of ST3 for the HAG and LAG. Genetic diversity analysis showed a high genetic diversity of ST3 (haplotype diversity: 0.846; nucleotide diversity: 0.014) in the rhesus macaques, but a high genetic differentiation (F_ST > 0.25) and a low gene flow (Nm = 0.09) between the HAG and LAG.

CONCLUSION

Our study, which is the first investigation on Blastocystis infection in multiple wild rhesus macaque populations in China, indicates a potential risk of zoonotic transmission of Blastocystis in the study areas. Blastocystis ST3 showed high genetic diversity in wild rhesus macaques and significant genetic differentiation between the HAG and LAG. Our results provide fundamental information on the genetic diversity and prevalence of Blastocystis in wild rhesus macaque populations.

Levels of Genetic Variants Among Symptomatic Blastocystis Subtypes and their Relationship to Mucosal Immune Surveillance in the Precancerous Colons of Experimentally Infected Rats

PURPOSE

The relationship between the genetic diversity of Blastocystis and immune surveillance in precancerous colons with blastocystosis is still under investigation. This study aimed to identify the genetic Blastocystis variants among 54 symptomatic human isolates and their relationship to mucosal immune surveillance in the precancerous polyps of experimentally infected rats.

METHODS

Polymerase chain reaction and high-resolution melting (PCR/HRM) curves discriminated human symptomatic Blastocystis isolates into subtypes (STs)/intrasubtypes, which were orally administered to rats to induce experimental infection. Then, the mucosal immune responses of the infected colons were evaluated in relation to polyp formation through immunostaining to identify mucus MUC2 and determine mucosal immune cell (goblet, lymphocyte and mast) counts, secretory IgA levels and parasitic intestinal invasion.

RESULTS

ST1, ST3, and ST4 were found in 18.5% (10/54), 54.7% (29/54), and 27.8% (15/54) of the samples, respectively. Then, the HRM curve discriminated ST3 into the wild, mutant, and heterozygous [17/54 (31.5%), 5/54 (9.3%), and 7/54 (12.9%)] intrasubtypes. ST1 and ST4 had no genetic variations. Precancerous polyps were detected in the colons of 40.5% of the infected rats. ST1 constituted 14.7% of these cases, while the wild, mutant, and heterozygous intrasubtypes of ST3 showed polyps in 12.9%, 5.5%, and 5.5% of cases, respectively. Only 1.9% of the polyps were related to ST4. MUC2 showed weak immunostaining in 44.5% of the infected colons, and 38.9% were polyp inducers. Low goblet cell numbers and high interepithelial lymphocyte counts were significantly associated with polyp formation, particularly with ST1 and wild ST3. Among the polyp inducers, high numbers of mast cells were detected in wild ST3 and ST4, while a low number was found with heterozygous ST3. The level of secretory IgA was low in polyp-inducing STs. Most of the results were statistically significant.

CONCLUSION

Immunosurveillance showed a potential relationship between ST1 and the ST3 intrasubtypes and precancerous polyps. This relationship may provide insight into the prevention and/or development of new immunotherapeutic strategies to combat colorectal cancer.

Distribution and Phylogenetic Analysis of Subtypes and Alleles of Blastocystis sp. in the Stool Samples Collected from Patients with Gastrointestinal Complaints in İzmir, Turkey

PURPOSE

Blastocystis sp. is one of the most prevalent intestinal protozoa found in humans and many other animals. The present study aimed to examine the distribution and genetic diversity of Blastocystis sp. in stool samples from patients with gastrointestinal complaints in İzmir, Turkey.

METHODS

All stool samples of 439 patients with gastrointestinal complaints were examined by native-Lugol and trichrome staining. To investigate the presence of Blastocystis sp. in stool samples, DNA was isolated, and PCR was performed with the barcode region in the SSU rRNA gene. PCR positive samples were sequenced to identify subtypes and alleles of Blastocystis sp.

RESULTS

The prevalence of Blastocystis sp. was found to be 16.6% (73/439) in patients with gastrointestinal complaints in İzmir, Turkey. Three different Blastocystis sp. subtypes were identified. ST3 (28/55; 51.0%) was the most common subtype followed by ST2 (19/55; 34.5%) and ST1 (8/55; 14.5%). Itching and diarrhea were the most prominent clinical symptoms in Blastocystis sp. positive patients. When clinical symptoms and subtypes were compared, diarrhea was found in 62.5%, 47.4%, and 46.4% of patients with ST1, ST2, and ST3 subtypes, respectively. In addition, itching was found in 37.5%, 32.1%, and 21.1% of patients with ST1, ST3, and ST2, respectively. Six distinct alleles were identified by allele analysis of Blastocystis 18S rRNA gene: allele 4 for ST1, alleles 9, 11, and 12 for ST2, and alleles 34 and 36 for ST3. In this study, Blastocystis sp. was detected in 16 of 21 districts, including the central and rural districts of İzmir. Although ST1 was detected in central districts, it was not found in rural districts.

CONCLUSION

This study provides comprehensive data on the prevalence and molecular epidemiology of the genetic diversity at the level of subtypes and alleles of Blastocystis sp. in different districts of İzmir province in Turkey. To the best of our knowledge, this is the first study which evaluates the distribution of subtypes and alleles of Blastocystis sp. according to PCR and SSU rRNA gene sequencing in patients with gastrointestinal complaints in different districts of İzmir province in Turkey.

Blastocystis occurrence in water sources worldwide from 2005 to 2022: a review

There has been increasing interest in the study of Blastocystis in the last two decades. Many studies have been carried out in human and animal hosts including environmental sources, but there is little or no information on the occurrence of Blastocystis in water sources worldwide. Therefore, this study aimed at assessing the occurrence of Blastocystis in water sources across the world from 2005 to 2022, noting the method of detection and the distribution of the subtypes from various water sources. A literature search was performed on internet-based databases including Google search, PubMed, Scopus, and Web of Science. Upon application of the criteria for inclusion, 25 articles revealing the occurrence of Blastocystis in water sources in 15 countries were included in the review. Blastocystis occurrence varies across water sources ranging from 0% in a drinking water source in Venezuela to 100% in rivers; well water, stored water, and fishpond in Nepal and Malaysia; and fountain water, irrigation water, and rainwater in Italy, Spain, and Thailand. The occurrence of the parasite was significantly associated with the coliform count, temperature, conductivity, dissolved oxygen, turbidity, total dissolved solids, and chemical oxygen demand. A total of 11 Blastocystis subtypes were identified in water sources worldwide, namely, ST1-ST8, ST10, ST23, and ST26 in which ST1 and ST3 were the most prevalent subtypes. Considering the importance of Blastocystis as a waterborne parasite, the subtype distribution and morphological distinction in water sources need to be carried out using molecular and electron microscopic techniques. Existing studies have covered only about 10% of the world's countries.

Subtypes and phylogenetic analysis of Blastocystis sp. isolates from West Ismailia, Egypt

In Egypt, Blastocystis sp. is not yet on the diagnostic list of parasitology reports, and information about its subtypes (STs) is scarce. This study investigated its prevalence and its STs/alleles, performed phylogenetic analysis, and considered the distribution of risk factors associated with Blastocystis sp. infections in West Ismailia, Ismailia governorate. Sociodemographic data, exposure factors, and previous parasitic infection status were recorded for symptomatic and asymptomatic individuals. Microscopy, polymerase chain reaction, sequencing, and phylogenetic analysis for Blastocystis sp. isolated from fecal samples were performed. Eighty Blastocystis sp.-infected individuals (15.3%) were examined. The age of the individuals ranged between 0.60 and 85.0 (mean 17.10 ± 15.70), the male/female ratio was 33/47, and the asymptomatic/symptomatic ratio was 55/25. The findings demonstrate clear evidence of direct contact with animals, poor water quality, and previous parasitic infections. Eleven samples yielded three Blastocystis STs (ST1: allele 4, ST2: alleles 9 and 12, and ST3: allele 34), with ST3 (45.5%) representing the most common subtype. Phylogenetic analysis with a robust bootstrap revealed three distinct clades for isolates of each subtype. This study updates the epidemiological knowledge of the distribution of Blastocystis sp. STs in Egypt and expands the current understanding of the prevalence, risk factor frequencies, and genetic diversity of this protist in the studied area.

Rare Occurrence of Blastocystis in Pet Animals and Their Owners in the Pomeranian Voivodeship in Poland in the Light of Literature Data

Blastocystis is an intestinal microeukaryote with ambiguous pathogenicity, commonly detected in human feces worldwide. It comprises at least 28 genetically diverse subtypes (STs), 12 of which also occur in a wide range of animal species, giving rise to suspicion of zoonotic transmission. To investigate this, we conducted a molecular study of 145 stool samples of pet animals, and 67 of their owners, living in an urban area in Poland. Blastocystis was detected in only three (2.1%) animal samples (of two bearded agamas and a leopard gecko), while all dogs, cats, and pet rodents were Blastocystis-negative. Blastocystis was also present in three (4.5%) owners of animals, but they were cat owners, not reptile owners, and the subtypes identified in them differed significantly from those of reptiles. Additionally, the frequency of Blastocystis in different groups of dogs (depending on how they were kept) was analyzed. This work is the first to find Blastocystis in pet reptiles, and we encourage further investigation of Blastocystis in this poorly examined group of animals, as well as continued study on the transmission of this microorganism between humans and animals.

Presence and genetic diversity of enteric protists in captive and semi-captive non-human primates in côte d’Ivoire, Sierra Leone, and Peru

Little information is currently available on the occurrence and genetic diversity of pathogenic and commensal protist species in captive and semi-captive non-human primates (NHP) resident in zoological gardens or sanctuaries in low- and medium-income countries. In this molecular-based study, we prospectively collected individual faecal samples from apparently healthy NHP at the Abidjan Zoological Garden (AZG) in Côte d’Ivoire, the Tacugama Sanctuary (TS) in Sierra Leone, and the Quistococha Zoological Garden (QZG) in Peru between November 2018 and February 2020. We evaluated for the presence of pathogenic (Cryptosporidium spp., Entamoeba histolytica, Giardia duodenalis, Blastocystis sp., Enterocytozoon bieneusi, Balantioides coli) and commensal (Entamoeba dispar, Troglodytella abrassarti) protist species using PCR methods and Sanger sequencing. Giardia duodenalis was the most prevalent species found (25.9%, 30/116), followed by Blastocystis sp. (22.4%, 26/116), and E. dispar (18.1%, 21/116). We detected E. bieneusi (4.2%, 1/24) and T. abrassarti (12.5%, 3/24) only on NHP from AZG. Cryptosporidium spp., E. histolytica, and B. coli were undetected at the three sampling sites investigated here. Sequence analyses revealed the presence of zoonotic sub-assemblages BIII (n = 1) in AZG and BIV (n = 1) in TS within G. duodenalis. We identified Blastocystis subtype ST3 (100%, 6/6) in AZG, ST1 (80.0%, 12/15), ST2 (6.7%, 1/15), and ST3 (13.3%, 2/15) in TS, and ST2 (80.0%, 4/5) and ST3 (20.0%, 1/5) in QZG. The only E. bieneusi isolate detected here was identified as zoonotic genotype CAF4. Our PCR-based data indicate that potentially pathogenic protist species including G. duodenalis, Blastocystis sp., E. bieneusi, and B. coli are present at variable rates in the three NHP populations investigated here. The identification of zoonotic genotypes within these species indicates that human-NHP transmission is possible, although the extent and directionality of these events need to be elucidated in future molecular surveys.

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Giardia and Blastocystis are highly prevalent in confined non-human primates.

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Diarrhoea-causing Cryptosporidium and Entamoeba histolytica were undetected.

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First description of Enterocytozoon bieneusi genotype CAF4 in non-human primates.

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Confined non-human primates harbour protist species with zoonotic potential.

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Cross-species (including human) transmission is possible in zoos and sanctuaries.

Interactions between Blastocystis subtype ST4 and gut microbiota in vitro

BACKGROUND

Blastocystis ST4 is a common protistan parasite of the gastrointestinal tract of humans and a wide range of animals. While it has been suggested that colonization with ST4 is associated with healthy gut microbiota, how ST4 influences the gut microbiota remains poorly studied. This study aimed to examine the interactions between ST4 and several intestinal bacteria using in vitro co-culture systems, and to further investigate the mechanism of interaction and its effect on the epithelial barrier integrity of HT-29 cells.

METHODS

Seven intestinal bacteria Bacteroides fragilis, Bifidobacterium longum, Bacillus subtilis, Bacteroides vulgatus, Escherichia coli, Enterococcus faecalis, and Lactobacillus brevis were co-cultured with Blastocystis ST4 in vitro. Flow cytometry and quantitative reverse-transcription polymerase chain reaction (qRT-PCR) were used to determine the role of reactive oxygen species (ROS) and bacteria oxidoreductase genes, respectively, in response to Blastocystis co-incubation. Transepithelial electrical resistance (TEER) and flux assays were performed to assess the effect of microbiota representatives on the integrity of the intestinal epithelial barrier.

RESULTS

Co-incubation with Blastocystis ST4 showed a beneficial influence on most intestinal bacteria, while ST4 significantly inhibited the growth of B. vulgatus, a common pathogen in the genus Bacteroides. The decrease in B. vulgatus when co-incubated with Blastocystis ST4 was associated with high levels of ROS and the upregulation of oxidative stress-related genes. Furthermore, co-incubation with Blastocystis ST4 was able to protect the intestinal epithelial barrier from damage by B. vulgatus.

CONCLUSIONS

This study demonstrated, for the first time, that Blastocystis ST4 has beneficial effects on intestinal commensal bacteria in vitro, and can inhibit the growth of pathogenic B. vulgatus. Combined with previous microbiome research on ST4, our data suggest that ST4 may be a beneficial commensal.

Amplicon-based next-generation sequencing of eukaryotic nuclear ribosomal genes (metabarcoding) for the detection of single-celled parasites in human faecal samples

Comprehensive detection and differentiation of intestinal protists mostly rely on DNA-based methods. Here, we evaluated next-generation sequencing of eukaryotic nuclear ribosomal genes (metabarcoding) for the detection and differentiation of intestinal eukaryotic protists in the stool of healthy Tunisian individuals.

Thirty-six faecal DNA samples previously evaluated by microscopy and ameboid species-specific PCRs were tested. The hypervariable regions V3-V4 and V3-V5 of the 18S rRNA gene were amplified using three universal eukaryotic primer sets and sequenced using Illumina®MiSeq sequencing. In addition, real-time PCR assays were used to detect Dientamoeba fragilis, Giardia duodenalis, and Cryptosporidium spp.

The metabarcoding assay detected Blastocystis (subtypes 1, 2, and 3) and archamoebid species and subtypes (Entamoeba dispar, Entamoeba hartmanni, Entamoeba coli RL1 and RL2, Endolimax nana, Iodamoeba bütschlii RL1) in 27 (75%) and 22 (61%) of the 36 stool samples, respectively. Meanwhile, the assay had limited sensitivity for flagellates as evidenced by the fact that no Giardia-specific reads were found in any of the five Giardia-positive samples included, and Dientamoeba-specific reads were observed only in 3/13 D. fragilis-positive samples. None of the samples were positive for Cryptosporidium by any of the methods. In conclusion, a large variety of intestinal eukaryotic protists were detected and differentiated at species and subtype level; however, limited sensitivity for common flagellates was observed.

Blastocystis One Health Approach in a Rural Community of Northern Thailand: Prevalence, Subtypes and Novel Transmission Routes

Blastocystis is the most commonly found eukaryote in the gut of humans and other animals. This protist is extremely heterogeneous genetically and is classified into 28 subtypes (STs) based on the small subunit ribosomal RNA (SSU rRNA) gene. Numerous studies exist on prevalence of the organism, which usually focus on either humans or animals or the environment, while only a handful investigates all three sources simultaneously. Consequently, understanding of Blastocystis transmission dynamics remains inadequate. Our aim was to explore Blastocystis under the One Health perspective using a rural community in northern Thailand as our study area. We surveyed human, other animal and environmental samples using both morphological and molecular approaches. Prevalence rates of Blastocystis were 73% in human hosts (n = 45), 100% in non-human hosts (n = 44) and 91% in environmental samples (n = 35). Overall, ten subtypes were identified (ST1, ST2, ST3, ST4 ST5, ST6, ST7, ST10, ST23, and ST26), eight of which were detected in humans (ST1, ST2, ST3, ST4, ST5, ST7, ST10, and ST23), three in other animals (ST6, ST7, and ST23), while seven (ST1, ST3, ST6, ST7, ST10, ST23, and ST26) were found in the environment. In our investigation of transmission dynamics, we assessed various groupings both at the household and community level. Given the overall high prevalence rate, transmission amongst humans and between animals and humans are not as frequent as expected with only two subtypes being shared. This raises questions on the role of the environment on transmission of Blastocystis. Water and soil comprise the main reservoirs of the various subtypes in this community. Five subtypes are shared between humans and the environment, while three overlap between the latter and animal hosts. We propose soil as a novel route of transmission, which should be considered in future investigations. This study provides a thorough One Health perspective on Blastocystis. Using this type of approach advances our understanding on occurrence, diversity, ecology and transmission dynamics of this poorly understood, yet frequent gut resident.

Evolutionary and phylogenetic analyses of the barcoding region suggest geographical relationships among Blastocystis sp., ST3 in humans

Blastocystis sp., has 21 distinct subtypes of which ST3 thought to be the most prevalent subtype. This study aims to analyze the global variations of ST3. In total, 496 sequences with more than 400 nucleotides from Asia, Europe, Africa, and America were included in this study. Results show that allele 34 was the most prevalent allele in all continents. The lowest and highest allele diversity were observed in Europe and Africa, respectively. The nucleotide diversity ranged from 0.0077 in Europe to 0.02 in Africa, and haplotype diversity ranged from 0.461 in America to 0.6 in Africa. The haplotype network and Bayesian structure showed at least two major clusters including Asia and Europe-Africa-America. Tajima's D values for all continents were negative and statistically significant, indicating an excess of rare nucleotide variants. Similarly, the Fu's FS test showed negative values for all regions, indicating an excess of rare haplotypes. Pairwise F_ST exhibited a high genetic differentiation between Asia and other continents. Mismatch analysis for all populations showed a unimodal distribution. Our findings indicate that there are two probable major clusters of Blastocystis sp. ST3, a cluster which is shared between Europe, Africa, and America, and a cluster which is restricted to Asia.

Molecular Characterization of Blastocystis in Captive and Free-Ranging New World Primates, Platyrrhini

PURPOSE

Blastocystis species are widely distributed micro-eukaryote parasites found in both human and nonhuman primates. Despite having a global distribution, descriptions of Blastocystis subtype diversity in neotropical primates is largely limited to captive animals. The aim of this study was to molecularly characterize the presence of Blastocystis in free-ranging black-headed night monkeys, Aotus nigriceps, and to analyze Blastocystis heterogeneity in primates of the Parvorder Platyrrhini.

METHODS

We analyzed Blastocystis small sub-unit ribosomal DNA (SSUrDNA) from both A. nigriceps and Azara's night monkey, A. azarae boliviensis, in Southeastern Peru. We also included additional Blastocystis sequence from other neotropical primate studies to explore the distribution and host specificity of Blastocystis subtypes (ST) throughout the neotropics.

RESULTS

Thirteen percent of A. nigriceps samples were Blastocystis positive. Only ST8 was amplified in A. nigriceps and this partial DNA sequence was highly similar to ST8 sequence previously obtained from a human in Brazil. In our analysis of all available Blastocystis SSU sequences from primates of the Parvorder Platyrrhini, we found 15 monophyletic lineages corresponding to previously described subtypes ST1-ST10, ST12-15, and ST17.

CONCLUSIONS

Blastocystis SSU sequences amplified from A. nigriceps fecal samples shared high sequence similarity to isolates found in several other neotropical primates, Alouatta palliata, A. caraya, Ateles fusciceps, and Lagothrix. Similar subtypes have been found in human and captive primates which supports the possibility of transmission when in close contact. Expanded sampling of sympatric neotropical primates in the wild will establish whether subtypes and clades are limited to taxonomic group or whether transmission occurs between overlapping species.

Prevalence, subtypes and risk factors of Blastocystis spp. infection among pre- and perimenopausal women

Background

Blastocystis spp. are considered pathogenic or commensal organisms, although the majority of researchers suggest that these are neglected pathogens. The main aim of this study was to determine the prevalence and subtype distribution of Blastocystis spp. in pre- and perimenopausal women, with respect to socio-demographic (age and place of residence), and epidemiological factors, as well as drinking tap water, contact with domestic animals, traveling abroad, health status, and presence of gastrointestinal symptoms. Additionally, the objective was to compare hematological and biochemical parameters of Blastocystis spp. infected and uninfected women.

Methods

The study included 425 women aged 45–60. Their stool samples were examined microscopically and analyzed by a conventional polymerase chain reaction (cPCR).

Results

Blastocystis spp. were detected in 6.1% of pre- and perimenopausal women. Molecular analysis of the stool samples identified seven Blastocystis subtypes (ST1–ST4, ST6, ST7, and ST9). Blastocystis subtypes 2 and 3 were the most prevalent. The presence of Blastocystis spp. was not significantly related to socio-demographic and epidemiological factors. There were also no significant associations between Blastocystis spp. and blood parameters, or gastrointestinal symptoms.

Conclusion

This study complements the limited available data on the prevalence of Blastocystis spp. in pre- and perimenopausal women. It is also the first report showing the presence of Blastocystis subtype 9 in Poland.

Frequency and distribution of Blastocystis sp. subtypes in patients with spondyloarthritis in Bogotá, Colombia

Although Blastocystis sp. is one of the most prevalent intestinal parasites worldwide, its role as a pathogen remains unclear. The use of molecular techniques to assess the genetic heterogeneity of Blastocystis sp. has become important to understand its function in some intestinal pathologies and if it is a key component of intestinal microbiota. Spondyloarthritis is a group of immune-mediated autoinflammatory diseases in which microbial dysbiosis in the gut (including parasites, bacteria and fungi) and intestinal inflammation are common features apparently associated with the pathophysiology of these disorders. This study included 74 patients diagnosed with spondyloarthritis and 57 systemically healthy individuals (included as controls), who were screened for intestinal parasites. Blastocystis sp. was detected in 68% and 73% of the patients with spondyloarthritis and controls, respectively. In faecal samples positive for Blastocystis sp., an 18S rRNA gene fragment of Blastocystis sp. was amplified and sequenced to identify their genetic sub-types. Patients with spondyloarthritis showed similar frequencies of ST1, ST2 and ST3 subtypes of Blastocystis sp. (30% each). The same subtypes were observed in controls, wherein almost 60% of the samples showed ST3. In addition, ST6 was found only in one sample from each group. ST1 subtype showed the greatest genetic variability. Although the same subtypes were detected in both patients with spondyloarthritis and controls, subtype prevalence studies conducted in Colombia indicate an association between ST3 and individuals with irritable bowel syndrome. This opens an interesting research avenue to further study of the epidemiology of Blastocystis sp. and its possible relationship with intestinal conditions in immunocompromised patients.

Occurrence and molecular characterization of Cryptosporidium spp., Giardia duodenalis, Enterocytozoon bieneusi, and Blastocystis sp. in captive wild animals in zoos in Henan, China

BACKGROUND

Captive wild animals in zoos infected with Cryptosporidium spp., Giardia duodenalis, Enterocytozoon bieneusi, and Blastocystis sp. can be sources of zoonotic infections and diseases. Therefore, to investigate the distribution of these pathogens in captive wild animals of zoos in Henan, China, a total of 429 fresh fecal samples were collected from six zoos in Henan, China. The infection rates of Cryptosporidium spp., G. duodenalis, E. bieneusi, and Blastocystis sp. were determined by PCR analysis of corresponding loci. Positive results for Cryptosporidium (C. parvum and C. hominis) were subtyped based on the (gp60) gene.

RESULTS

The overall prevalence was 43.1% (185/429), and the prevalence of Cryptosporidium, Giardia duodenalis, Enterocytozoon bieneusi, and Blastocystis sp. were 2.8% (12/429), 0.5% (2/429), 20.8% (89/429), and 19.1% (82/429), respectively. Five Cryptosporidium species, namely, C. hominis, C. parvum, C. muris, C. andersoni, and C. macropodum, were identified in this study. Cryptosporidium parvum was further subtyped as IIdA19G1. Two Giardia duodenalis assemblages (A and E) were also identified. A total of 20 Enterocytozoon bieneusi genotypes were detected, including 18 known (BEB6, D, HND-1, CD7, SDD1, Henan-IV, KIN-1, CHK1, Peru8, Henan-V, CHG11, CHG-1, CHS9, CHG21, Type-IV, CHC9, CM5, and CHB1) and 2 novel genotypes (CHWD1 and CHPM1). A total of nine subtypes of Blastocystis sp. (ST1, ST2, ST3, ST5, ST6, ST7, ST10, ST13, and ST14) were identified in captive wild animals in zoos in the present study. Cryptosporidium andersoni, nine Enterocytozoon bieneusi genotypes, and five Blastocystis subtypes were here first identified in new hosts.

CONCLUSIONS

Our study has expanded the host ranges of these four pathogens. The data indicate that animals in zoos can commonly be infected with these four zoonotic pathogens, and animals in zoos are potential sources of zoonotic infections in humans.

Molecular Characterization of Blastocystis from Animals and Their Caregivers at the Gdańsk Zoo (Poland) and the Assessment of Zoonotic Transmission

Blastocystis is a highly genetically diverse gut protist commonly found in humans and various animals. The role of animals in human infection is only partly understood. The aim of this study was to determine the host specificity and possibility of zoonotic transmission of this microorganism. Subtypes of Blastocystis isolated from 201 zoo animals and their 35 caregivers were identified by sequencing of the SSU rRNA gene. Blastocystis was found in 26.86% of animal and 17.14% of human samples. Both mammalian (ST1-ST3, ST5, ST8, ST10, ST13, ST14) and non-mammalian subtypes were detected. Of the subtypes found in non-human primates (ST1, ST2, ST3, and ST13), two subtypes (ST1 and ST3) were also detected in humans. The presence of identical ST1 sequences in three monkeys and their caregiver indicates the possibility of direct transmission of Blastocystis between these animals and humans. Detection of ST5 only in wild boars and peccaries, ST8 only in Marsupial, ST10 and ST14 only in Bovidae, and non-mammalian subtypes in reptiles suggests higher host specificity for these subtypes, and indicates that their transmission between animals and humans is unlikely. Additionally, this was probably the first time that ST5 was found in peccaries, ST2 in patas monkeys, and ST8 in red kangaroos.

Epidemiology and subtype distribution of Blastocystis in humans: A 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 (χ²) 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.

Identification of Multiple Blastocystis Subtypes in Domestic Animals From Colombia Using Amplicon-Based Next Generation Sequencing

Blastocystis is frequently reported in fecal samples from animals and humans worldwide, and a variety of subtypes (STs) have been observed in wild and domestic animals. In Colombia, few studies have focused on the transmission dynamics and epidemiological importance of Blastocystis in animals. In this study, we characterized the frequency and subtypes of Blastocystis in fecal samples of domestic animals including pigs, minipigs, cows, dogs, horses, goats, sheep, and llama from three departments of Colombia. Of the 118 fecal samples included in this study 81.4% (n = 96) were positive for Blastocystis using a PCR that amplifies a fragment of the small subunit ribosomal RNA (SSU rRNA) gene. PCR positive samples were sequenced by next generation amplicon sequencing (NGS) to determine subtypes. Eleven subtypes were detected, ten previously reported, ST5 (50.7%), ST10 (47.8%), ST25 (34.3%), ST26 (29.8%), ST21 (22.4%), ST23 (22.4%), ST1 (17.9%), ST14 (16.4%), ST24 (14.9%), ST3 (7.5%), and a novel subtype, named ST32 (3.0%). Mixed infection and/or intra -subtype variations were identified in most of the samples. Novel ST32 was observed in two samples from a goat and a cow. To support novel subtype designation, a MinION based sequencing strategy was used to generate the full-length of the SSU rRNA gene. Comparison of full-length nucleotide sequences with those from current valid subtypes supported the designation of ST32. This is the first study in Colombia using NGS to molecularly characterize subtypes of Blastocystis in farm animals. A great diversity of subtypes was observed in domestic animals including subtypes previously identified in humans. Additionally, subtype overlap between the different hosts examined in this study were observed. These findings highlight the presence of Blastocystis subtypes with zoonotic potential in farm animals indicating that farm animals could play a role in transmission to humans.

Detection and molecular identification of Blastocystis isolates from humans and cattle in northern Egypt

Blastocystis is one of the less well-understood waterborne protozoa of medical and veterinary importance. The present study aimed to detect, identify, and subtype Blastocystis in cattle and humans in northern Egypt and to investigate the potential for zoonotic transmission. Fecal samples were collected from 136 humans (68 in contact with animals and 68 no animal contact) and 190 cattle from a rural area in Kafr El-Sheikh Province, Egypt. All samples were microscopically examined by direct wet mount technique and cultured in Jones' medium. Genomic DNA was extracted from positive cultures. A region of the Blastocystis small subunit ribosomal ribonucleic acid (SSU rRNA) gene was amplified using PCR. Blastocystis subtypes were identified by sequencing of the amplified SSU rRNA gene. The relatedness of sequence types obtained in this study and others submitted in GenBank was compared according to their genetic relatedness. Out of 136 human and 190 cattle samples, Blastocystis was detected in 53 (38.9%) and 37 (19.4%), respectively using either culture or direct wet mount. Blastocystis SSU rRNA gene was amplified in 55 samples (32 humans and 23 animals). Six subtypes were identified (STs 1-3 in humans and ST4, ST10 and ST14 in cattle) and were distinguishable with inter (up to 0.075) and intra (up to 0.024) subtype variations. A close phylogenetic relationship between human and animal isolated STs 1-4 was demonstrated. To the best of our knowledge, this is the first study to investigate the the potentiality for zoonotic transmission of certain Blastocystis subtypes in northern Egypt.

PREVALENCE OF BLASTOCYSTIS SUBTYPES IN HEALTHY VOLUNTEERS IN NORTHEASTERN POLAND

Blastocystis is a common enteric protist that is linked to intestinal and extra-intestinal diseases. At least 24 subtypes (STs) have been described, with the main colonization of ST1-ST4 in humans. In our attempt to determine the distribution of Blastocystis STs in Olsztyn and surroundings in northeastern Poland, 319 stool samples from volunteers were subjected to copro-ELISA and PCR testing. Positive findings were identified in 77, 48, and 46 of the samples via copro-ELISA, PCR, and sequencing, respectively. Blastocystis colonization was not associated with gender or dwelling place but was statistically higher in people age 60-69 yr (32.6%). Five STs (ST1-ST4, ST7) were identified, in which ST3 (37%) was most prevalent, followed by ST2 (19.6%), ST1 (17.4%), ST4 (13%), and ST7 (8.7%). The current study revealed a similar rate of microorganism colonization in Polish volunteers compared to other developed countries, without significant differences in gender and dwelling place. Significant statistical differences were found in different age groups, where Blastocystis was highly detected in elderly people. In the current study, PCR was the most plausible method based on the sequencing results.

Blastocystis in the faeces of children from six distant countries: prevalence, quantity, subtypes and the relation to the gut bacteriome

Background

Blastocystis is a human gut symbiont of yet undefined clinical significance. In a set of faecal samples collected from asymptomatic children of six distant populations, we first assessed the community profiles of protist 18S rDNA and then characterized Blastocystis subtypes and tested Blastocystis association with the faecal bacteriome community.

Methods

Stool samples were collected from 244 children and young persons (mean age 11.3 years, interquartile range 8.1–13.7) of six countries (Azerbaijan 51 subjects, Czechia 52, Jordan 40, Nigeria 27, Sudan 59 and Tanzania 15). The subjects showed no symptoms of infection. Amplicon profiling of the 18S rDNA was used for verification that Blastocystis was the most frequent protist, whereas specific real-time PCR showed its prevalence and quantity, and massive parallel amplicon sequencing defined the Blastocystis subtypes. The relation between Blastocystis and the stool bacteriome community was characterized using 16S rDNA profiling.

Results

Blastocystis was detected by specific PCR in 36% (88/244) stool samples and was the most often observed faecal protist. Children from Czechia and Jordan had significantly lower prevalence than children from the remaining countries. The most frequent subtype was ST3 (49%, 40/81 sequenced samples), followed by ST1 (36%) and ST2 (25%). Co-infection with two different subtypes was noted in 12% samples. The faecal bacteriome had higher richness in Blastocystis-positive samples, and Blastocystis was associated with significantly different community composition regardless of the country (p < 0.001 in constrained redundancy analysis). Several taxa differed with Blastocystis positivity or quantity: two genera of Ruminococcaceae were more abundant, while Bifidobacterium, Veillonella, Lactobacillus and several other genera were undrerrepresented.

Conclusions

Asymptomatic children frequently carry Blastocystis, and co-infection with multiple distinct subtypes is not exceptional. Prevalence and quantity of the organism clearly differ among populations. Blastocystis is linked to both faecal bacteriome diversity and its composition.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04859-3.

Molecular Subtyping of Blastocystis sp. Isolated from Farmed Animals in Southern Italy

Blastocystis is a common intestinal protist distributed worldwide, infecting humans and a wide range of domestic and wild animals. It exhibits an extensive genetic diversity and, so far, 25 distinct small subunit ribosomal RNA (SSU rRNA) lineages termed subtypes (STs)) have been characterized; among them, 12 have thus far been reported in humans. The aims of the present study were to detect and genetically characterize Blastocystis sp. in synantropic animals to improve our current knowledge on the distribution and zoonotic transmission of Blastocystis STs in Italy. Samples were collected from N = 193 farmed animals and submitted to DNA extraction and PCR amplification of the SSU rRNA. Blastocystis was detected in 60 samples (31.08%) and successfully subtyped. Phylogenetic analysis evidenced that the isolates from fallow deer, goats, and pigs (N = 9) clustered within the ST5; those from pheasants (N = 2) in the ST6; those from chickens (N = 8) in the ST7; those from sheep (N = 6) in the ST10; and those from water buffaloes (N = 9) in the ST14 clade. The comparison between the present isolates from animals and those previously detected in humans in Italy suggested the animal-to-human spillover for ST6 and ST7. The present study represents the widest Blastocystis survey performed thus far in farmed animals in Italy. Further epidemiological studies using molecular approaches are required to determine the occurrence and distribution of Blastocystis STs in other potential animal reservoirs in Italy and to define the pathways of zoonotic transmission.

Frequency of enteroparasites in Cebidae and Callitrichidae primates at the Zoológico de Cali, Colombia: zoonotic implications

Introducción.

Los enteroparásitos pueden generar problemas en animales bajo cuidado humano en zoológicos y centros de acogida. Los animales silvestres presentan bajas cargas parasitarias, pero estas pueden ser mayores y llevar a manifestaciones clínicas cuando se trata de animales resguardados en recintos, lo que aumenta los gastos en tratamientos y cuidados médicos. Por otro lado, algunos enteroparásitos pueden causar infecciones zoonóticas en los cuidadores, los visitantes y otros animales del zoológico, así como afectar los programas de recuperación de especies amenazadas de extinción.

Objetivos.

Determinar la presencia y prevalencia de enteroparásitos con potencial de transmisión zoonótica en primates de las familias Cebidae y Callitrichidae del Zoológico de Cali, entre septiembre y noviembre de 2017.

Materiales y métodos.

Se hizo un estudio transversal prospectivo, para lo cual se recolectaron muestras seriadas de 50 individuos pertenecientes a siete especies de dos familias de primates y se analizaron mediante examen coprológico, flotación y coloración Kinyoun, entre septiembre y noviembre de 2017.

Resultados.

Según su prevalencia, los géneros de parásitos hallados en las siete especies de primates evaluadas, fueron Blastocystis spp., Trichomonas spp., Giardia spp., Entamoeba spp., Strongyloides spp., Cyclospora sp. y Trichuris sp.

Conclusiones.

Por lo menos, seis de los géneros de parásitos identificados tienen implicaciones zoonóticas, lo cual hace necesario establecer las posibles vías de infección de los primates del Zoológico de Cali e implementar protocolos de manejo que reduzcan el riesgo de transmisión a los humanos y a otros animales de la colección. Además, se presenta la información relevante sobre el potencial zoonótico de los enteroparásitos hallados.

Parasitic Intestinal Protists of Zoonotic Relevance Detected in Pigs by Metabarcoding and Real-Time PCR

Several parasite species are shared between humans and pigs. We explored the application of next-generation sequencing-based metabarcoding supplemented with real-time PCR to fecal DNAs from 259 samples from 116 pigs in Denmark to detect and differentiate single-celled intestinal parasites of zoonotic relevance. Enterocytozoon bieneusi, Balantioides coli, and Giardia duodenalis were observed in 34/37 (92%), 148/259 (57%), and 86/259 (33%) samples, respectively. Entamoeba polecki ST1, E. polecki ST3, and Entamoeba hartmanni were detected in 104/259 (40%), 161/259 (62%), and 8/259 (3%) samples, respectively. Metabarcoding and real-time PCR detected Cryptosporidium in 90/259 (35%) and 239/259 (92%) of the samples, respectively, with Cryptosporidium suis and Cryptosporidium scrofarum observed in nearly equal proportions. Blastocystis subtypes 1, 3, 5, and 15 were found in 72 (28%), 6 (2%), 176 (68%), and 36 (14%) of 259 samples, respectively. Iodamoeba was identified in 1/259 samples (<1%), while none of 37 tested samples was positive for Dientamoeba fragilis. Our results illustrate how metabarcoding exemplifies a 'one-fits-many' approach to detecting intestinal single-celled parasites in feces supplemented with real-time PCR for selected parasites. Using metabarcoding with pathogen-specific assays may help detect emerging and previously underdetected pathogens and further elucidate the role of micro-eukaryotic parasites in human and animal health and disease.

Genetic characterization of Blastocystis from poultry, livestock animals and humans in the southwest region of Iran-Zoonotic implications

Blastocystis is the most common intestinal parasite found in epidemiological studies in Iran. The genus Blastocystis comprises multiple subtypes (ST), evincing the existence of extensive intrageneric diversity. Meanwhile, information on Blastocystis STs in domestic animals in Iran is limited. This study was designed to identify the prevalence and subtype distribution of Blastocystis in domestic animals and to evaluate the extent of zoonotic origin of human Blastocystis carriage. A total of 395 faecal samples from farm animals (220 from poultry, 100 from sheep and 75 from cattle) and 23 Blastocystis positive samples from humans (available from the previous report of this study and included for reference) from the Khuzestan province, southwestern Iran, were analysed. Standard parasitological methods and PCR-based analysis of the SSU-rRNA gene were used. Overall, 115 (29.1%; 95% CI, 26.5%-31.6%) of the animals were positive for Blastocystis sp. by parasitological methods. The highest colonization rate was found in cattle (50.6%, 38/75), followed by sheep (32.0%, 32/100) and poultry (20.4%, 45/220). Eight Blastocystis STs were identified among 55 sequenced isolates from animals (n = 32) and humans (n = 23): ST3 (27.3%), ST14 (25.4%), ST1 (12.7%), ST7 (12.7%), ST2 (9.1%), ST6 (7.3%), ST5 (3.6%) and ST10 (1.8%). Blastocystis ST1 and ST3 were found in both human and non-human hosts, and examples of shared alleles (strains) were observed. Meanwhile, ST2 was observed only in humans, ST5 only in sheep, ST6 only in poultry and ST10 in only cattle. This is the most comprehensive report of Blastocystis STs in farm animals in Iran.

Occurrence and Genetic Diversity of Protist Parasites in Captive Non-Human Primates, Zookeepers, and Free-Living Sympatric Rats in the Córdoba Zoo Conservation Centre, Southern Spain

Little information is currently available on the epidemiology of parasitic and commensal protist species in captive non-human primates (NHP) and their zoonotic potential. This study investigates the occurrence, molecular diversity, and potential transmission dynamics of parasitic and commensal protist species in a zoological garden in southern Spain. The prevalence and genotypes of the main enteric protist species were investigated in faecal samples from NHP (n = 51), zookeepers (n = 19) and free-living rats (n = 64) by molecular (PCR and sequencing) methods between 2018 and 2019. The presence of Leishmania spp. was also investigated in tissues from sympatric rats using PCR. Blastocystis sp. (45.1%), Entamoeba dispar (27.5%), Giardia duodenalis (21.6%), Balantioides coli (3.9%), and Enterocytozoon bieneusi (2.0%) (but not Troglodytella spp.) were detected in NHP. Giardia duodenalis (10.5%) and Blastocystis sp. (10.5%) were identified in zookeepers, while Cryptosporidium spp. (45.3%), G. duodenalis (14.1%), and Blastocystis sp. (6.25%) (but not Leishmania spp.) were detected in rats. Blastocystis ST1, ST3, and ST8 and G. duodenalis sub-assemblage AII were identified in NHP, and Blastocystis ST1 in zookeepers. Giardia duodenalis isolates failed to be genotyped in human samples. In rats, four Cryptosporidium (C. muris, C. ratti, and rat genotypes IV and V), one G. duodenalis (assemblage G), and three Blastocystis (ST4) genetic variants were detected. Our results indicate high exposure of NHP to zoonotic protist species. Zoonotic transmission of Blastocysts ST1 was highly suspected between captive NHP and zookeepers.

Molecular Diversity of Giardia duodenalis, Cryptosporidium spp., and Blastocystis sp. in Symptomatic and Asymptomatic Schoolchildren in Zambézia Province (Mozambique)

Infections by the protist enteroparasites Giardia duodenalis, Cryptosporidium spp., and, to a much lesser extent, Blastocystis sp. are common causes of childhood diarrhoea in low-income countries. This molecular epidemiological study assesses the frequency and molecular diversity of these pathogens in faecal samples from asymptomatic schoolchildren (n = 807) and symptomatic children seeking medical attention (n = 286) in Zambézia province, Mozambique. Detection and molecular characterisation of pathogens was conducted by polymerase chain reaction (PCR)-based methods coupled with Sanger sequencing. Giardia duodenalis was the most prevalent enteric parasite found [41.7%, 95% confidence interval (CI): 38.8‒44.7%], followed by Blastocystis sp. (14.1%, 95% CI: 12.1‒16.3%), and Cryptosporidium spp. (1.6%, 95% CI: 0.9‒2.5%). Sequence analyses revealed the presence of assemblages A (7.0%, 3/43) and B (88.4%, 38/43) within G. duodenalis-positive children. Four Cryptosporidium species were detected, including C. hominis (30.8%; 4/13), C. parvum (30.8%, 4/13), C. felis (30.8%, 4/13), and C. viatorum (7.6%, 1/13). Four Blastocystis subtypes were also identified including ST1 (22.7%; 35/154), ST2 (22.7%; 35/154), ST3 (45.5%; 70/154), and ST4 (9.1%; 14/154). Most of the genotyped samples were from asymptomatic children. This is the first report of C. viatorum and Blastocystis ST4 in Mozambique. Molecular data indicate that anthropic and zoonotic transmission (the latter at an unknown rate) are important spread pathways of diarrhoea-causing pathogens in Mozambique.

[Current view on Blastocystis species: clinical forms, diagnosis and treatment]

The symptomatic form of Blastocystis spp. infection not only with mild diarrhea or dysentery-like syndrome, but also with the development of severe ulcerative necrotic lesions of the intestine. Meanwhile, the pathogenicity of these microorganisms should not be exaggerated, due to majority asymptomatic cases or infection transmission with minor impaired bowel function.

Use of Oxford Nanopore MinION to generate full-length sequences of the Blastocystis small subunit (SSU) rRNA gene

Background

Blastocystis sp. is one of the most common enteric parasites of humans and animals worldwide. It is well recognized that this ubiquitous protist displays a remarkable degree of genetic diversity in the SSU rRNA gene, which is currently the main gene used for defining Blastocystis subtypes. Yet, full-length reference sequences of this gene are available for only 16 subtypes of Blastocystis in part because of the technical difficulties associated with obtaining these sequences from complex samples.

Methods

We have developed a method using Oxford Nanopore MinION long-read sequencing and universal eukaryotic primers to produce full-length (> 1800 bp) SSU rRNA gene sequences for Blastocystis. Seven Blastocystis specimens representing five subtypes (ST1, ST4, ST10, ST11, and ST14) obtained both from cultures and feces were used for validation.

Results

We demonstrate that this method can be used to produce highly accurate full-length sequences from both cultured and fecal DNA isolates. Full-length sequences were successfully obtained from all five subtypes including ST11 for which no full-length reference sequence currently exists and for an isolate that contained mixed ST10/ST14.

Conclusions

The suitability of the use of MinION long-read sequencing technology to successfully generate full-length Blastocystis SSU rRNA gene sequences was demonstrated. The ability to produce full-length SSU rRNA gene sequences is key in understanding the role of genetic diversity in important aspects of Blastocystis biology such as transmission, host specificity, and pathogenicity.

Succinate dehydrogenase gene as a marker for studying Blastocystis genetic diversity

Blastocystis has been reported as the most common eukaryotic microorganism residing in the intestines of both humans and animals, with a prevalence of up to 100% in some populations. Since this is a cryptic species, sequence polymorphism are the single strategy to analyses its genetic diversity, being traditionally used the analysis of ssu rRNA gene sequence to determine alleles and subtypes (STs) for this species. This multicopy gene has shown high diversity among different STs, making necessary to explore other genes to assess intraspecific diversity. This study evaluated the use of a novel genetic marker, succinate dehydrogenase (SDHA), for the typing and evaluation of the genetic diversity and genetic population structure of Blastocystis. In total, 375 human fecal samples were collected and subjected to PCR, subtyped using the ssu rRNA marker, and then the SDHA gene was amplified via PCR for 117 samples. We found some incongruences between tree topologies for both molecular markers. However, the clustering by ST previously established for Blastocystis was congruent in the concatenated sequence. SDHA showed lower reticulation (The origination of a lineage through the partial merging of two ancestor lineages) signals and better intra ST clustering ability. Clusters with geographical associations were observed intra ST. The genetic diversity was lower in the marker evaluated compared to that of the ssu rRNA gene (nucleotide diversity = 0.03344 and 0.16986, respectively) and the sequences analyzed showed population expansion with genetic differentiation principally among STs. The ssu rRNA gene was useful to explore interspecific diversity but together with the SDHA gene the resolution power to evaluate intra ST diversity was higher. These results showed the potential of the SDHA marker for studying the intra ST genetic diversity of Blastocystis related with geographical location and the inter ST diversity using the concatenated sequences.

A Study on the Prevalence and Subtype Diversity of the Intestinal Protist Blastocystis sp. in a Gut-Healthy Human Population in the Czech Republic

Blastocystis sp. is a common intestinal protist colonizing the human intestine the prevalence of which varies across non-industrialized and industrialized countries. Its role in the human gut ecosystem remains unclear due to persisting gaps in knowledge of epidemiology and factors affecting gut colonization. Here, we aimed to expand the knowledge of the epidemiology of Blastocystis sp. in the gut-healthy humans in one of the industrialized European countries, including the distribution of its subtypes, the correlation between its occurrence and several factors such as lifestyle, contact with animals, age, and sex. A total of 288 stool samples were obtained from asymptomatic individuals over the entire age-range and 136 samples from animals with which the volunteers were in frequent contact. All samples were examined in parallel by PCR and xenic in vitro culture. Blastocystis sp. was detected in samples from both human and non-human hosts. In humans, the overall prevalence was 24% and eight subtypes were found; in animals, the prevalence was 10%, and only five subtypes were detected. A higher incidence of Blastocystis sp. was observed in individuals (i) traveling outside Europe, (ii) in frequent contact with livestock, and (iii) over 50 years of age. We found no effect on gender on Blastocystis sp. colonization.

Summary

This study provides data on the prevalence and diversity of the gut protist Blastocystis sp. and its subtypes in a gut-healthy human population with emphasis on several factors such as contact with animals, lifestyle, age, and gender.

Blastocystis in domesticated and wild mammals and birds

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.

Current status of Blastocystis sp. in animals from Southeast Asia: a review

Blastocystis is the most frequently observed eukaryotic gastrointestinal symbiont in humans and animals. Its low host specificity and zoonotic potential suggest that animals might serve as possible reservoirs for transmission. The prevalence and subtype distributions of Blastocystis sp. in animal populations in Southeast Asia, a hotspot for zoonotic diseases, are reviewed. Recommendations for future research aimed at understanding the zoonotic role of Blastocystis are also included. Seven countries have, so far, reported Blastocystis infection in various animals, such as livestock, poultry, companion animals, and non-human primates. Pigs were the most studied animals, and there were records of 100% prevalence in pigs, cattle, and ostriches. Using polymerase chain reaction (PCR)-based approaches, twelve Blastocystis sp. subtypes (STs), namely ST1, ST2, ST3, ST4, ST5, ST6, ST7, ST8, ST9, ST10, ST12, and ST14 have been recognised infecting animals of Southeast Asia. ST1 and ST5 were the most frequently identified, and Malaysia observed the most diverse distribution of subtypes. Further investigations on Blastocystis sp. in various animal hosts, using adequate sample sizes and uniform detection methods, are essential for a better understanding of the distribution of this organism. Detailed genome studies, especially on STs shared by humans and animals, are also recommended.

Characterization of prevalence and genetic subtypes of Blastocystis sp. in wild and domestic Suidae of central Italy aided by amplicon NGS

Blastocystis spp. is a common single-celled intestinal symbiont, comprising several genetic subtypes (ST) and transmissible by animal-to-animal, human-to-human, animal-to-human and, possibly, human-to-animal routes. This work was designed to explore the presence of Blastocystis in sympatric domestic and wild suids and their ability to carry zoonotic STs, in a condition of widespread opportunity to come in contact with the microorganism through their shared water and food resources, and other carriers. We sampled 42 and 37 stool samples from wild boars and domestic pigs, respectively. STs were first identified by PCR followed by Sanger sequencing. Sequences represented in double-band PCR products or in Sanger chromatograms displaying multiple peaks, were resolved by next generation sequencing (NGS). Twenty-six (61.9%) wild boar and 26 (70.2%) pig samples were PCR-positive, respectively. ST3, ST5 and ST15 were found in 3.8%, 38.4% and 80.8% of the positive wild boars and 11.5%, 88.5%, 11.5% of the positive pigs, respectively. ST1 was found only in pigs (3.8%). STs 5 and 15 were common in both groups of animals, but in reversed proportions, suggesting preferential colonization. We found significantly different ST distributions among wild boars and domestic pigs. This might indicate that lifestyle differences between the two populations influence their risk for contracting certain subtypes, or that ST5 and ST15 can colonize preferentially wild or domestic animals. Based on the STs described here, wild boars and domestic pigs can act as reservoirs with zoonotic potential. The ability of suids to carry zoonotic STs appears to be higher when using NGS than Sanger sequencing, and resolution of complex sequencing profiles is imperative before excluding the presence of STs of human concern.

Prevalence and Subtype Distribution of Blastocystis sp. in Senegalese School Children

Blastocystis sp. is an enteric protozoan that frequently colonizes humans and many animals. Despite impacting on human health, data on the prevalence and subtype (ST) distribution of Blastocystis sp. remain sparse in Africa. Accordingly, we performed the first multicenter and largest epidemiological survey ever conducted on Blastocystis sp. for this continent. A total of 731 stool samples collected from healthy school children living in 10 villages of the northwestern region of Senegal were tested for the presence of Blastocystis sp. by real-time polymerase chain reaction followed by subtyping of positive samples. Considerable variation in prevalence between villages (51.7 to 100%) was evident with the overall prevalence being 80.4%. Mixed infections were identified in 23% of positive individuals. Among 453 school children with a single infection, ST2 was predominant, followed by ST1, ST3, ST7, ST10, and ST14; this is the first report of ST10 and ST14 in humans. Genetic polymorphisms were evident at the intra-ST level with the identification of numerous ST1 to ST3 genotypes. ST1 showed the greatest intra-ST diversity followed by ST2 and ST3. The prevalence and distribution of STs and genotypes varied among target villages, pointing to several potential infection sources, including human-to-human, zoonotic, and waterborne transmission.

Distribution and molecular analysis of Blastocystis subtypes from gastrointestinal symptomatic and asymptomatic patients in Iran

INTRODUCTION

Blastocystis is a common intestinal parasite of human and animal hosts. The parasite has 17 subtypes, and among those at least nine subtypes (ST1-ST9) are found in human hosts.

OBJECTIVE

The aim of the present study was to investigate the presence of different subtypes of Blastocystis spp. among the patients referred to Velayat hospital of Qazvin province, Iran.

METHODS

Overall, 864 stool samples were examined by using formalin-ethyl acetate concentration method and Trichrome staining. All specimens were cultured in clotted fetal bovine medium. Later, DNA extraction and PCR amplification of 18S ribosomal RNA gene region was conducted and phylogenetic tree constructed.

RESULTS

The results revealed 7.9% (68/864) of the study population were infected with Blastocystis. Intestinal symptoms were observed in 61% (36/59) of individuals positive for Blastocystis, with abdominal pain in 58% (21/36) of cases which was more frequent than other intestinal signs. No significant relationship was observed among the study variables. By molecular and phylogenetic analysis, three subtypes ST1 (45%), ST2 (30%) and ST3 (23%) of parasite were identified.

CONCLUSION

This study showed ST1 subtype was the predominant subtype among the positive specimens, meanwhile the highest haplotype and nucleotide diversity were clarified in ST3 subtype.

First molecular subtyping and phylogeny of Blastocystis sp. isolated from domestic and synanthropic animals (dogs, cats and brown rats) in southern Iran

BACKGROUND

Blastocystis sp. is a common intestinal protist that infects humans and many animals globally. Thus far, 22 subtypes (STs) have been identified in mammalian and avian hosts. Since various STs are common to humans and animals, it was suggested that some human infections might arise from zoonotic transmission. Therefore, the aim of this study was to assess the presence of Blastocystis sp. in domestic (dogs and cats) and synanthropic animals (rats) of Fars Province, Iran, and to genetically characterize the samples.

METHODS

A total of 400 fresh faecal samples from 154 dogs, 119 cats, and 127 rats were inspected by direct microscopy, Wheatley's trichrome staining, in vitro culture, and 18S rRNA gene nested-PCR. Finally, sequencing and phylogenetic analyses were performed.

RESULTS

Out of 400 samples, 47 (11.8%) and 61 (15.3%) samples were detected as positive by direct wet mount and culture, respectively. Molecular analysis detected a larger number of positive samples (n = 70, 17.5%): nested-PCR showed that 29 (18.8%) dogs, 21 (17.7%) cats, and 20 (15.8%) rats were infected by Blastocystis sp. Sequence analysis of positive samples indicated the presence of zoonotic STs in all investigated host species. Specifically, ST2 (allele 9), ST3 (allele 34), ST4 (allele 94), ST7 (allele 99), ST8 (allele 21), and ST10 (allele 152) were detected in dogs; ST1 (allele 2), ST3 (allele 34), ST4 (allele 94), ST10 (allele 152), and ST14 (allele 159) were detected in cats; and ST1 (allele 2), ST3 (allele 34), and ST4 (allele 92) were detected in rats.

CONCLUSIONS

Our data suggest that domestic dogs and cats can serve as possible reservoirs for in-contact humans, especially those who handle shelter-resident and client-owned animals. Moreover, rats as synanthropic animals can function as a potential source of human infections. Conversely, humans can act as a source of infections to animals. These results should be reinforced in future molecular epidemiological studies.