Direct characterization of Blastocystis from faeces by PCR and evidence of zoonotic potential

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.

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.

Blastocystis infection among diarrhea outpatients in Ningbo, Southeast China: A potential zoonotic health threat

BACKGROUND

Blastocystis is one of the important zoonotic parasites which can infect humans and various animals worldwide and has become a growing global public health concern. The study aims to obtain the data of Blastocystis infection and the information of the genetic characteristic.

METHODS

In the present study, 489 fecal samples were collected from diarrhea outpatients in Ningbo, Zhejiang province, and were examined the presence of Blastocystis by polymerase chain reaction combined with sequencing.

RESULTS

A total of 10 samples (2.04%, 10/489) were positive for Blastocystis with no significant difference among sex and age groups, respectively. Eight samples were successfully sequenced, and five zoonotic ST3 and three zoonotic ST1 with two new sequences were identified.

CONCLUSIONS

We first demonstrated the occurrence of Blastocystis infection in diarrhea outpatients in Ningbo, with two zoonotic subtypes (ST1 and ST3) and two new sequences being characterized. Meanwhile, mixed infection of Blastocystis and E. bieneusi was found which indicates the importance of investigation of multiple parasites. Finally, more extensive studies will be needed to better understand the transmission of Blastocystis at human-animal-environment interface and provide evidence for the development of one health strategies for the prevention and control of such diseases.

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.

Molecular characterization of Blastocystis subtypes in symptomatic patients from the southern region of Syria

Blastocystis sp. is an enteric protist found in humans and a wide range of animal hosts. Genetic variations were established among the 38 different subtypes detected so far, 14 of which are commonly found in human and animal hosts. The aim of the present study is to estimate the prevalence of the common Blastocystis subtypes and evaluate the possible correlation with several variables (gender, age, symptoms, domestic animals…), among patients from the southern region of Syria. Fecal samples were collected from individuals suffering from gastrointestinal complaints. Microscopic examination along with genotype analyses using seven pairs of subtype-specific primers was performed. Our results revealed the presence of Blastocystis sp. in 46 isolates out of the 60 samples microscopically studied (76.7%); single infection was detected in 24 isolates whereas co-infection with other protozoa was identified in 22 ones. Molecular detection targeting the SSU rRNA gene revealed a 100% positive presence of Blastocystis sp. in all the samples. Genotyping results detected the presence of five different subtypes (ST1-ST5) with varying proportions. However, ST1 was the dominant subtype observed (66.7%). Mixed subtype infections were found in 9 isolates (15%). Three samples remained undefined, nonetheless. Our statistical results showed no significant correlation between Blastocystis STs infection and the different studied variables. In conclusion, this study provides the first genetic characterization of Blastocystis subtypes prevalence in patients from the southern region of Syria. ST1 distribution was highly predominant. Further molecular studies are needed to estimate the prevalence of Blastocystis sp. infection in other regions in Syria and to understand the epidemiology and sources of transmission to humans.

An update on the distribution of Blastocystis subtypes in the Americas

Blastocystis is an intestinal protist that presents worldwide distribution, colonizes animal and human hosts, and is classified into at least 34 ribosomal subtypes (STs). Herein, we conducted an update based on studies reporting Blastocystis-positive samples obtained from diverse hosts in the Americas. We described the distribution throughout the continent by assembling maps representing the distribution of STs and the most important 18S-rRNA alleles. Thirty-nine articles from the previous study, "A summary of Blastocystis subtypes in North and South America," and forty-one additional articles from March 2019 to March 2022 were considered. The most common subtype described was ST3, representing the highest percentage of positive samples. Other recently identified STs include ST12, ST13, and ST16 in humans, and ST10, ST14, and ST17 in animals. Novel subtypes have also been described in this continent. We assembled and updated the distribution of Blastocystis in the Americas. We hope this delivers new understandings and knowledge of this microorganism's prevalence and genetic diversity.

Prevalence of Blastocystis sp. in freshwater fishes, poultry, and caprine from Penang, Malaysia

Blastocystis is an enigmatic intestinal protist of humans and many animals. There is growing interest in its potential as an enteric pathogen, and the possible role of domestic and in-contact animals as reservoirs for human infection. The purpose of this study was to determine the prevalence of Blastocystis infection in fishes, poultry, and caprine in Penang, Malaysia. A total of 353 faecal samples/intestinal contents, consisting of 123 intestinal contents from freshwater fishes, 96 intestinal contents of commercially barn-reared chickens, 84 intestinal contents of barn-reared quails, and 50 faecal samples of caprine (29 from meat goats and 21 from dairy goats) were collected. Faecal sample/intestinal content from each animal was subjected to in-vitro cultivation method using Jones' medium supplemented with 10% horse serum. The respective colonization frequencies for dairy and meat goats were 47.6% and 31.0%, whereas 26.1% was recorded for chickens and 16.7% for quails. None of the freshwater fishes were found infected with Blastocystis. The organism was most commonly seen as spherically shaped vacuolated forms and cell diameter was significantly larger in poultry than in caprine. For further studies, molecular characterization of Blastocystis in poultry and livestock animals in the study area is highly recommended.

Current global status, subtype distribution and zoonotic significance of Blastocystis in dogs and cats: a systematic review and meta-analysis

Background

Blastocystis is a common intestinal protozoa found in animal and human fecal samples, with over 1 billion individuals infected worldwide. Since domestication, dogs and cats have had a close bond with humans. However, their close proximity poses a potential health risk since they may harbor several zoonotic agents. A global estimate of Blastocystis infection and subtype (ST) distribution in dogs and cats would therefore be of great health importance to humans.

Methods

We performed a comprehensive systematic search of four English-language databases (PubMed, Scopus, Google Scholar, Web of Science) for relevant articles up to 8 November 2021. The random-effects model was used to make pooled estimates with confidence intervals (CIs).

Results

In total, we identified 49 publications that met our inclusion criteria and subsequently analyzed the 65 datasets in these articles, of which 23 and 42 datasets were on cats and dogs, respectively. Among the 2934 cats included in the 23 datasets, which involved 16 countries, the prevalence rate of Blastocystis infection was 9.3% (95% CI 5.3–15.9%). The prevalence of Blastocystis infection was slightly lower [7%, 95% CI 4.7–10.4%) among the 7946 dogs included in the 42 datasets, involving 23 countries. The sensitivity analysis showed that no remarkable variation in the estimates upon the stepwise removal of each dataset. Higher ST diversity was found among the examined dogs (ST1-8, ST10, ST23, ST24) than among cats (ST1-4, ST10, ST14). Among dogs, ST3 was the most frequent ST (41.3%), followed by ST2 (39.3%), ST1 (30.9%), ST4 (13.4%), ST8 (12.7%), ST10 (11%) and ST5 (8.1%). Also among dogs, each of ST6, ST7, ST23 and ST24 was observed in only one study. Of the ST found in the cats examined, ST4 (29.5%), followed by ST10 (22.5%), ST1 (19.8%) and ST3 (17.6%) were the most common. A single study also reported the presence of both ST2 and ST14 in cats. With respect to zoonotic Blastocystis STs (ST1–ST9 and ST12), eight were reported from dogs (ST1-ST8) and four were isolated from cats (ST1–ST4), showing the implication of dog and cats in zoonotic transmission.

Conclusions

Taken together, our results show that elucidation of the true epidemiology and ST distribution of Blastocystis in dogs and cats demands more comprehensive studies, particularly in the negelected regions of the world.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05351-2.

An Association Between Blastocystis Subtypes and Colorectal Cancer Patients: A Significant Different Profile from Non-cancer Individuals

PURPOSE

Blastocystis is a common enteric human parasite of non-conclusive pathogenicity which may be determined by subtype (ST) variation. Colorectal cancer (CRC) is considered one of the primary causes of cancer mortality. Blastocystis ST7 has been shown to reduce beneficial intestinal microbiota and may exacerbate CRC. This study assessed the possible association between Blastocystis STs and CRC in comparison to non-cancer patients.

MATERIAL AND METHODS

A total of 200 fecal samples were obtained from CRC (100) and non-CRC (100) individuals attending Beni-Suef University Hospital, Egypt. Blastocystis was searched for in all samples using microscopy and culturing. Positive subculture samples were genetically sequenced and subtyped using conventional polymerase chain reaction (PCR). Blastocystis STs were determined by sequencing and a phylogenetic tree was created. Related patient characteristics and tumor stages were analyzed for association with presence of Blastocystis.

RESULTS

Blastocystis was identified in 52% and 42% of CRC and non-cancer individuals, respectively. ST1, 2, and 3 were isolated from both cancer and non-cancer individuals; however, for the first time, ST7 was only isolated from CRC stool samples with significant association. Associated patient characteristics were evaluated as predictors.

CONCLUSION

Blastocystosis is highly prevalent in CRC patients, predominantly in the latest CRC grades and stages. To the best of our knowledge, this is the first study to report the identification of Blastocystis ST7 in CRC patients. To determine whether certain STs of Blastocystis are associated with CRC would require further research, including the role played by gut microbiota.

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.

Simultaneous analysis of the intestinal parasites and diet through eDNA metabarcoding

Agricultural expansion and intensification are having a huge impact on plant and arthropod diversity and abundance, affecting food availability for farmland birds. Difficult food access, in turn, can lead to immunosuppression and a higher incidence of parasites. In the studies designed to examine changes in the diet of birds and their parasites, metabarcoding is proving particularly useful. This technique requires mini-barcodes capable of amplifying the DNA of target organisms from faecal environmental DNA. To help to understand the impact of agricultural expansion on biodiversity, this study sought to design and identify mini-barcodes that might simultaneously assess diet and intestinal parasites from the faeces of farmland birds. The capacity to identify diet and parasites of two existing and three newly-developed mini-barcodes was tested "in silico" in relation to the behaviour of a reference eukaryotic barcode. Among the newly designed mini-barcodes, MiniB18S_81 showed the higher taxonomic coverage of eukaryotic taxa and a greater amplification and identification capacity for diet and parasite taxa. Moreover, when it was tested on faecal samples from five different steppe bird species, MiniB18S_81 showed high taxonomic resolution of the most relevant diet and parasite phyla, Arthropoda, Nematoda, Platyhelminthes and Apicomplexa, at the order level. Thus, the mini-barcode developed emerges as an excellent tool to simultaneously provide detailed information regarding the diet and parasites of birds, essential for conservation and management. This article is protected by copyright. All rights reserved.

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.

Zoonotic Transmission of Blastocystis Subtype 1 among People in Eastern Communities of Thailand: Organic Fertilizer from Pig Feces as a Potential Source

Blastocystis sp., the most common intestinal protozoa, remains a public health problem among people in many countries, particularly in rural areas of developing countries. The infection usually reflects poor sanitation in communities by waterborne, zoonotic, and person-to-person transmission. Interestingly, at least 17 subtypes (STs) have been reported and are associated with a broad range of animal hosts, including humans. In this study, we reported potential evidence of zoonotic transmission of Blastocystis ST1 in rural communities of eastern Thailand where the overall prevalence of Blastocystis infection was 15.7%. Two major and three minor subtypes were found to be distributed unequally in this region. Of 5 STs, only ST1 was found to be associated with pig feces in an open farm system that produced organic fertilizer for agriculture uses in the community. This finding suggests that properly protective contact and standard production of organic fertilizer from pig feces by-products could be key factors for reducing the prevalence of Blastocystis infection and prevent Blastocystis reinfection among people in the community.

IMPORTANCEBlastocystis sp. remains a public health problem among people, particularly in rural areas of many developing countries. The infection usually reflects poor sanitation in communities by waterborne, zoonotic, and person-to-person transmission. In this study, we reported potential evidence of zoonotic transmission of Blastocystis subtype 1 (ST1) in rural communities of eastern Thailand. Two major and three minor subtypes were found to be unequally distributed in this region. Interestingly, only ST1 was found to be associated with pig feces in an open farm system that produced organic fertilizer for agriculture uses in the community. The finding makes significant contributions to genetic and molecular investigations of microbial topics of practical value and suggest that properly protective contact and standard production of organic fertilizer from pig feces by-products could be key factors for reducing the prevalence of Blastocystis infection and prevent Blastocystis reinfection among people in the community.

Investigation of neglected protists Blastocystis sp. and Dientamoeba fragilis in immunocompetent and immunodeficient diarrheal patients using both conventional and molecular methods

Introduction

The clinical significance of Blastocystis sp. and Dientamoeba fragilis in patients with gastrointestinal symptoms is a controversial issue. Since the pathogenicity of these protists has not been fully elucidated, testing for these organisms is not routinely pursued by most laboratories and clinicians. Thus, the prevalence of these organisms and the subtypes of Blastocystis sp. in human patients in Turkey are not well characterized. This study aimed to determine the prevalence of Blastocystis sp. and D. fragilis in the diarrheic stool samples of immunodeficient and immunocompetent patients using conventional and molecular methods and to identify Blastocystis sp. subtypes using next generation sequencing.

Material and methods

Individual stool specimens were collected from 245 immunodeficient and 193 immunocompetent diarrheic patients between March 2017 and December 2019 at the Gazi University Training and Research Hospital in Ankara, Turkey. Samples were screened for Blastocystis sp. and D. fragilis by conventional and molecular methods. Molecular detection of both protists was achieved by separate qPCRs targeting a partial fragment of the SSU rRNA gene. Next generation sequencing was used to identify Blastocystis sp. subtypes.

Results

The prevalence of Blastocystis sp. and D. fragilis was 16.7% and 11.9%, respectively as measured by qPCR. The prevalence of Blastocystis sp. and D. fragilis was lower in immunodeficient patients (12.7% and 10.6%, respectively) compared to immunocompetent patients (21.8% and 13.5%, respectively). Five Blastocystis sp. subtypes were identified and the following subtype distribution was observed: ST3 54.4% (n = 37), ST2 16.2% (n = 11), ST1 4.4% (n = 3), ST6 2.9% (n = 2), ST4 1.5% (n = 1), ST2/ST3 11.8% (n = 8) and ST1/ST3 8.8% (n = 6). There was no statistically significant difference in the distribution of Blastocystis sp. subtypes between immunocompetent and immunodeficient patients.

Conclusion and recommendation

Our findings demonstrated that Blastocystis sp. and D. fragilis are commonly present in immunocompetent and immunodeficient patients with diarrhea. This study is the first to use next generation sequencing to address the presence of Blastocystis sp. mixed subtypes and intra-subtype variability in clinical samples in Turkey.

Blastocystis sp. and Dientamoeba fragilis are single-cell parasites of the human intestine which are common worldwide and reported in cases with gastrointestinal symptoms. However, the role of Blastocystis sp. and D. fragilis in patients with gastrointestinal symptoms is still controversial because their presence is not always associated with symptoms. As some intestinal parasitic infections can cause severe illness in immunocompromised individuals careful consideration of intestinal protist infection is warranted. However, testing for Blastocystis sp. and D. fragilis is not routinely carried out by most laboratories and clinicians. Therefore, this study aimed to determine the prevalence of Blastocystis sp. and D. fragilis in immunocompetent and immunosuppressed patients with diarrhea by conventional and molecular methods. Both Blastocystis sp. and D. fragilis were detected more frequently by quantitative polymerase chain reaction than by conventional methods. Next generation sequencing was used to characterize the diversity and frequency of Blastocystis sp. subtypes and mixed subtypes in patients in Turkey. Five Blastocystis sp. subtypes (ST1, ST2, ST3, ST4 and ST6) were detected. ST3 was the most frequent subtype in both immunocompetent and immunosuppressed patients. Mono-infections were more common than mixed subtype infections. Our findings showed that Blastocystis sp. and D. fragilis are commonly present in immunocompetent and immunodeficient patients with diarrhea.

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.

Genotypes of Blastocystis sp. among elderly health checkup people in South Korea with a questionnaire on risk factors

Blastocystis sp. is a common zoonotic intestinal parasite of humans and animals, and has been classified into at least 17 distinct subtypes. Despite its potential impact on public health, the prevalence and subtype distribution of Blastocystis sp. have seldom been the study subject in South Korea. To determine the prevalence and subtype distribution of Blastocystis sp. and to obtain information on risk factors, we performed a cross-sectional study targeting elderly health checkup people, who visited Seoul Western Branch of the Korea Association of Health Promotion (KAHP) in October 2019. Stool samples were collected from 293 participants consisting of 128 males and 165 females with a mean age of 64.7 years (from 50 to 88 years) with a questionnaire on potential risk factors. All the samples were tested by PCR targeting the SSU rRNA gene of Blastocystis sp., and nucleotide sequences of positive samples were used to identify the subtypes. The overall prevalence of Blastocystis sp. was 9.2% (27/293). Among the positive samples, subtype 3 was predominant (59%; 16/27), followed by subtype 1 (41%; 11/27). No other subtypes were detected. In the univariable analysis, the age, sex, presence of digestive symptoms, source of drinking water, and history of drug intake were not significantly associated with Blastocystis sp. infection. Two parameters, including the Enterococcus hirae bacterial infection and the frequency of intake of cooked or boiled vegetables less than twice a week, showed statistical significance. However, the multivariable regression analysis revealed that only the latter parameter was statistically significant. The results suggested that subtypes 3 and 1 are the 2 major genotypes of Blastocystis sp. among elderly people in South Korea, and low frequency of consuming cooked or boiled vegetables is a potential risk factor.

Blastocystis spp. infection in cases of diarrhea: A pilot study from a tertiary care teaching hospital in Rishikesh, Uttarakhand, with a brief review of literature

CONTEXT

Intestinal parasitic infections (IPI) are among the most common infections throughout the world. Blastocystis spp. is a mysterious parasite which is commonly encountered in tropical countries. Its pathogenic status is unknown and there is a paucity of literature about this organism from the state of Uttarakhand, India.

AIMS

The aim was to estimate the prevalence of Blastocystis spp. in diarrheal stools.

SETTINGS AND DESIGN

This was a cross-sectional study conducted from January 2018 to July 2019.

SUBJECTS AND METHODS

Nonrepetitive stool samples of 187 consecutive patients of diarrhea attending the inpatient department and outpatient department of a tertiary care teaching hospital located in Rishikesh, Uttarakhand, were collected after obtaining informed written consent. These samples were subjected to wet mount microscopy and permanent staining.

STATISTICAL ANALYSIS USED

Fisher's exact test and Kappa coefficient were used in this study.

RESULTS

The mean age ± standard deviation of the patients was 36.04 ± 11.31 years with a male-to-female ratio of 1.49:1. The prevalence of IPI was 36.09%. Giardia intestinalis was the most common parasite. Blastocystis spp. was observed in 6.42% of the stool samples, majority of which were obtained from cases of chronic diarrhea. Moderate agreement (0.48) was observed between wet mount microscopy and permanent staining in the identification of Blastocystis spp.

CONCLUSIONS

This is the first study to assess the burden and role of different epidemiological and clinical profiles of Blastocystis spp. in Uttarakhand. More studies are required to know its pathogenesis and its role as opportunistic pathogen.

Investigation of Isolated Blastocystis Subtypes from Cancer Patients in Turkey

PURPOSE

It is not clear that Blastocystis remains without damage to the digestive tract or has a pathogenic effect in relation to subtypes in immunocompromised people, such as cancer patients. The present study aimed to investigate the frequency and subtype distribution of Blastocystis in cancer patients who were followed-up and treated in the Oncology clinic of Firat University Hospital and to determine the clinical signs of infected sufferers.

METHODS

201 patients aged ≥ 18 with a diagnosis of cancer were enrolled in this cross-sectional study. Patients' stool samples were examined between September 2017 and August 2019 by native-Lugol, trichrome staining. Microscopy-positive stool samples were subjected to DNA isolation and subtyped by Sequence Tagged Site (STS)-PCR analysis. The symptoms and demographic characteristics of the patients were also evaluated.

RESULTS

Totally, 29 (14.4%) samples were positive for Blastocystis after all methods. 15 (51.7%) out of 29 samples were successfully subtyped by the sequenced-tagged site(STS)-PCR, while 14 (48.3%) could not be typed. Three subtypes of Blastocystis were detected: ST3 (40%), ST2 (33%), ST1 (20%), and one mixed infections with ST1/ST2 (6%). There was no statistically significant difference in terms of clinical findings and demographic characteristics.

CONCLUSION

The outcomes of our study promote the idea that Blastocystis could be an asymptomatic and harmless commensal organism. However, more comprehensive molecular and clinical studies are needed to fully determine the pathogenicity and epidemiology of Blastocystis in cancer patients.

Next-generation sequencing reveals wide genetic diversity of Blastocystis subtypes in chickens including potentially zoonotic subtypes

Blastocystis sp. is an intestinal protist parasite commonly found in the feces of humans and animals worldwide. Blastocystis exhibits extensive genetic diversity and has been identified in humans and a variety of animals including other mammals and birds. Blastocystis subtypes do not exhibit strict host specificity which raises the possibility of zoonotic transmission through either direct contact or fecal contamination of food or water. However, reports detailing the subtypes and prevalence of Blastocystis in avian species are limited. Therefore, this study investigated the presence of Blastocystis in chickens by molecular characterization of the small subunit rRNA (SSU rRNA) gene. Fecal samples from 130 chickens were collected from local markets in Uberlândia and Belo Horizonte in the state of Minas Gerais, Brazil. To detect and identify subtypes of Blastocystis, a next-generation amplicon sequencing protocol was used. Forty-four of the 130 (33.8%) chickens examined were positive for Blastocystis. Blastocystis subtypes ST6 (23/130; 17.7%), ST7 (43/130; 33.1%), ST10 (1/130; 0.8%), ST14 (5/130; 3.8%), ST25 (1/130; 0.8%), and a novel subtype (ST29) (2/130; 1.5%) were observed. A nanopore sequencing strategy was used to obtain the near full-length SSU rRNA gene nucleotide sequence and validate novel subtype ST29. Mixed infections containing multiple subtypes were common and identified in 63.6% of Blastocystis-positive chickens. All positive samples contained one or both potentially zoonotic subtypes ST6 and ST7. The prevalence of Blastocystis in chickens was high, and molecular characterization mostly identified subtypes previously found in humans. Thus, chickens may be a source of human infection and environmental contamination.

A systematic review and meta-analysis on the global prevalence and subtypes distribution of Blastocystis sp. infection in cattle: A zoonotic concern

Blastocystosis is an interesting parasitosis, since the parasitic infection is still seriously neglected and a considerable zoonotic evidence is emerging. Blastocystis sp. infects the intestinal lumen of humans and a wide range of animals, while there is a lack of comprehensive information on Blastocystis epidemiology in cattle worldwide. Thus, the present systematic review and meta-analysis were performed by exploring four electronic databases (PubMed, Web of Science, Scopus, and Google scholar) for relevant published papers up to 7th November 2020, utilizing a random-effects model to pool estimations and assign 95 % confidence intervals (CIs). Results of 28 studies (29 datasets) on cattle showed a 24.4 % (95 % CI: 16.9-33.9 %) prevalence for Blastocystis infection. Also, 16 out of 26 reported subtypes (STs) were isolated from cattle, with ST10 (18 datasets) as the highest-reported [32.3 % (95 % CI: 21.6-45.3)] as well as ST24 and ST25 (one study each) as the lowest-reported STs [1.4 % (95 % CI: 0.2-9.1)]. Additionally, among nine well-known zoonotic STs (ST1-ST8 and ST12), all STs except for ST8 were reported from cattle worldwide, demonstrating this animal species as a potential reservoir for human infections. Meanwhile, the overall prevalence of Blastocystis in various subgroups (publication year, WHO regions, countries, continents, and age groups) was analyzed separately. The finding of the present review article highlights the cattle as a significant source of zoonotic transmission of Blastocystis infection to humans, which must be considered for preventive measures.

Molecular detection and subtype distribution of Blastocystis in farmed pigs in southern China

Blastocystis is one of the most common causative agents of intestinal diseases, which can cause enteric diseases in animals and humans. However, limited data is available on the prevalence or subtypes of Blastocystis infections in farmed pigs in southern China. In this study, a total of 396 fecal samples were collected from farmed pigs in three provinces in southern China in 2016, and screened for Blastocystis by PCR amplification of the small subunit rRNA (SSU rRNA) gene fragment. One hundred and seventy (42.93%) of the examined fecal samples were detected Blastocystis-positive, and two known zoonotic subtypes ST1 and ST5 were identified, with ST5 being the predominate subtype. Moreover, gender, age and region were considered as risk factors that associated with Blastocystis infection in farmed pigs. The present study revealed the prevalence and subtypes of Blastocystis infections in farmed pigs in southern China, which provided essential data for the control of Blastocystis infections in pigs, other animals and humans in China.

Occurrence and genotypes of Cryptosporidium spp., Giardia duodenalis, and Blastocystis sp. in household, shelter, breeding, and pet market dogs in Guangzhou, southern China

Cryptosporidium spp., Giardia duodenalis, and Blastocystis sp. are common intestinal protozoans that infect humans and animals worldwide. A survey that assessed the prevalence, molecular characteristics, and zoonotic potential of these pathogens was conducted on a variety of dogs in Guangzhou, southern China. A total of 651 canine stool samples from household (n = 199), shelter (n = 149), breeding (n = 237), and pet market dogs (n = 66) were collected from eight districts in Guangzhou. Cryptosporidium spp., Giardia duodenalis, and Blastocystis sp. were detected by PCR amplification of the SSU rRNA gene. Giardia duodenalis-positive specimens were further assigned into assemblages using the glutamate dehydrogenase gene. Cryptosporidium spp., G. duodenalis, and Blastocystis sp. were found in 21 (3.2%), 20 (3.1%), and 35 (5.4%) samples, respectively. The overall prevalence of shelter dogs (40.28%, 60/149) was significantly higher than that of household (3.0%, 6/199), breeding (2.1%, 5/237), and pet market dogs (7.5%, 5/66) (χ² = 154.72, df = 3, P < 0.001). Deworming in the past 12 months had a strong protective effect on the risk of contracting parasite infections (P < 0.001). No significant differences were detected between age or sex groups (P > 0.05). Dog-specific C. canis (n = 19) and zoonotic C. parvum (n = 2) were the only two Cryptosporidium species. Sequence analysis revealed the presence of three G. duodenalis assemblages: dog-specific assemblages D (n = 14) and C (n = 5), and cat-specific F (n = 1). Zoonotic Blastocystis ST3 (n = 28) was the dominant subtype, followed by ST1 (n = 6) and ST10 (n = 1). To our knowledge, this is the first large-scale investigation on the occurrence and molecular characteristics of Blastocystis sp. in dogs in China. Our results indicated that the dogs seemed to play a negligible role as reservoirs for Cryptosporidium spp. and G. duodenalis transmission to humans, but they are potential novel suitable hosts of Blastocystis sp. A strict sentinel surveillance system of dogs should be established to minimise the zoonotic risk of spreading blastocystosis among humans and dogs.

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.

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.

Molecular identification and subtypes distribution of Blastocystis sp. isolated from children and adolescent with cancer in Iran: evaluation of possible risk factors and clinical features

PURPOSE

This study aimed to determine the molecular characterization and subtype distribution of Blastocystis sp. isolated from cancer children and adolescents in Shiraz, Fars province, southwestern Iran.

METHODS

Overall, 200 fecal samples obtained from cancer children and adolescents under 18 years old (107 males and 93 females) and checked by microscopy, culture, and molecular methods (PCR). Possible etiological factors and clinical characteristics of Blastocystis infection were also evaluated and compared between Blastocystis infected and non-infected patients.

RESULTS

Thirteen of 200 (6.5%) stool samples were positive for Blastocystis by microscopy. While 21 of 200 (10.5%) were positive by culture, and 24 of 200 (12%) were positive by PCR. Out of 24 positive samples tested by PCR and sequencing, ST3 was reported as the most common subtype (nine samples, 37.5%), followed by ST2 (eight samples, 33.3%), ST1 (five samples, 20.9%), and ST7 (two samples, 8.3%). The prevalence of Blastocystis infection in males was significantly higher than females (p = 0.024). Also, Blastocystis was more prevalent in patients who had received at least eight chemotherapy cycles than fewer (p = 0.002). However, no associations were found between Blastocystis-positive rate and age, residence, type of cancers, or contact with animals. Also, there was no significant difference between frequency of Blastocystis subtypes in symptomatic and asymptomatic cancer patients.

CONCLUSIONS

Various controlled epidemiologic and topographic studies need to confirm or reject these possible associations with Blastocystis infection. The data from this study are an invaluable addition to the growing body of research studies on Blastocystis infection in cancer patients.

Development and evaluation of high-resolution melting curve analysis for rapid detection and subtyping of Blastocystis and comparison the results with sequencing

Blastocystis is a prevalent parasite that has a wide distribution. In order to design HRM real-time PCR, primers were selected from SSU rRNA gene to amplify specific fragment with different melting temperatures for each subtype of Blastocystis. Subsequently, HRM real-time PCR was performed and melting curve analysis was done by Rotor-Gene Q software. The results of HRM real-time PCR was then compared with sequence results of "barcoding region" of SSU rRNA gene of Blastocystis. To evaluate sensitivity of test, 10-fold serial dilutions of the parasite were prepared from ~ 10⁶ to 1 parasite per mL of stool sample and were investigated by HRM real-time PCR. In order to determine specificity of method, HRM real-time PCR was done for some microorganisms and Blastocystis-negative stool samples. In silico analysis showed that all seventeen subtypes of Blastocystis were distinguish. In vitro analysis revealed that the test discriminated subtypes with specific melting temperatures.

Diversity of Blastocystis subtypes in wild mammals from a zoo and two conservation units in southeastern Brazil

The enteric protist Blastocystis is one of the most commonly parasite reported in humans and a variety of animal hosts worldwide. Regarding genetic diversity, at least 17 subtypes (STs) have been identified in mammals and birds, with eight of them (ST1-8) infecting both humans and animals. Recently, isolates from wild mammalian species have been genetically characterized, however data is still scarce, mainly in Latin America. Here, we aimed to verify the occurrence and genetic diversity of Blastocystis in captive wild mammals kept in one zoo and in two units of protection and conservation in southeastern Brazil. A total of 78 fecal samples (14 pooled and 64 individual samples) were recovered from 102 wild mammals of 35 species included in the following orders: Primates, Carnivora, Artiodactyla, Pilosa, Rodentia and Marsupialia. Zoo and units staff were invited to participated but only 16 fecal samples could be screened. Based on the sequence analyses of SSUrDNA gene, out of 29 PCR products from animal samples, 51.7% (15/29) were successfully sequenced and five Blastocystis subtypes were identified as follows: ST1 (2/15; 13.3%), ST2 (2/15; 13.3%), ST3 (4/15; 26.6%), ST5 (2/15; 13.3%) and ST8 (5/14; 33.3%). Only four isolates from humans were sequenced and identified as ST1 (2 isolates), ST2 and ST3. It was observed that Blastocystis infecting non-human primates belong to ST1 and ST2 and mainly to ST3 and ST8, artiodactyls ST5, carnivores ST1 and ST5 and rodents ST1. In addition, this present study reports some interesting findings: (1) 63% (12/19) of Blastocystis isolates from animals and employees belonged to the potentially zoonotic subtypes ST1-ST3; (2) most of these isolates displayed high identity with publicly available DNA sequences from non-human primates and humans, including primate handlers; (3) Blastocystis ST5 was found infecting the northern tiger cat, a native South American felid and one of the species facing a high risk of extinction in Brazil.

First record of Leptospira and Blastocystis infections in captive flying squirrels (Trogopterus xanthipes) from Enshi County, China

In traditional Chinese medicine, the feces of flying squirrels have long been used to promote blood circulation and relieve bodily stasis. However, the excrement of flying squirrels may harbor zoonotic agents that could be hazardous to public health. To understand the occurrence of bacterial and parasitic infections in this species, we investigated selected zoonotic pathogens including Leptospira and Blastocystis in the urine and feces of flying squirrels in China. Urine and fecal samples from flying squirrels were collected from a family-owned flying squirrel farm located in Enshi County, Hubei Province in China. Leptospira and Blastocystis DNA was extracted from the urine and feces of flying squirrels, and used as targets for PCR amplification, using different specific primers. PCR amplification and DNA sequencing showed that 4.4% (3/69) of flying squirrels were positive for Leptospira, while 30.4% (21/69) of the animals were positive for Blastocystis. Notably, 1.4% (1/69) of flying squirrels were found to be co-infected with Leptospira and Blastocystis. Sequence analyses allowed for the detection of 3 Blastocystis subtypes (ST1, ST3 and ST13), and mixed infections of Blastocystis subtype 1 and subtype 3 were found in 4.4% (3/69) of flying squirrels. Phylogenetic analysis of the 16S ribosomal RNA gene (rrs2), the flagellin B gene (flaB), and outer membrane lipoprotein lipL32 gene (LipL32) sequences indicated that the Leptospira species detected in the study was L. interrogans. We concluded that flying squirrels from central China were infected with Leptospira and Blastocystis, suggesting that these animals can be a source of infection for their owners, and using fresh excrement from this animal as traditional medicine could be risky to human health. To the best of our knowledge, this is the first report of Leptospira and Blastocystis infection in flying squirrels from Enshi County, China. Our findings provide new data on the epidemiology of these pathogens in this region.

Molecular Subtyping of Blastocystis from Diverse Animals in the United Arab Emirates

The contribution of Blastocystis from non-human hosts to zoonotic transmission is only partly known. The objective of this study was to determine the distribution of Blastocystis genetic subtypes in different animal species in United Arab Emirates. A total of 114 stool samples were tested using PCR of the small subunit (SSU) rRNA gene and sequence analysis. Twenty-three Blastocystis-positive samples were identified. The following detection rates were observed: cattle, 22.7%; sheep, 63.6%; rabbits, 33.3%; rodents, 37.5%; reptiles, 21.2%. Four subtypes were identified in this study; ST4, ST10, ST14, and ST17; ST10 was isolated from sheep and cattle, corroborating previous data indicating that these are natural hosts for this subtype. Cases of mixed subtype colonization were also detected. Conspicuously, we found ST14 in rabbits. The discovery of ST17 in a squirrel indicates a novel host for this subtype. Furthermore, the discovery of ST4 in rodents suggests that these may serve as reservoir for human Blastocystis ST4 colonization. Six tortoises and one iguana were positive for Blastocystis. In conclusion, this is the first report of Blastocystis infection in various animals in the UAE. Apart from ST4, no potentially zoonotic subtypes were detected.

First genotyping of Blastocystis in yaks from Qinghai Province, northwestern China

Background

Blastocystis is a common protist that can infect domestic and wild animals worldwide. Yak (Bos grunniens), an ancient species which can survive in alpine regions, has supplied necessities to local residents in plateau areas for generations. However, the infections with Blastocystis in yaks has been ignored for a long time. In the present study, the infections and genotypes of Blastocystis spp. in domestic yaks from Qinghai Province (northwestern China) were explored.

Results

Of 1027 faecal samples collected from yaks in seven regions of Qinghai Province, northwestern China, the total prevalence of Blastocystis was 27.07% (278/1027) targeting the small subunit ribosome rRNA (SSU rRNA) gene. This protist was detected in yaks within each examined age group, geographical origin and season. Significant difference in prevalence was found in yaks from different geographical origins. The highest prevalence (48.94%) was observed in animals from Haixi county. Sequence analysis revealed three animal-specific subtypes (ST10, ST12 and ST14) of Blastocystis spp. in these yaks, with ST10 being the predominant subtype widely distributed in all investigated regions, seasons and age groups. Interestingly, this is the first report about subtype ST12 infecting yaks.

Conclusions

To our knowledge, this is the first systematic report on Blastocystis prevalence in yaks from China, and the findings provide fundamental data for establishing effective control measures for this protist in yaks as well as other animals in China.

A Simple Genotyping Method for Rapid Differentiation of Blastocystis Subtypes and Subtype Distribution of Blastocystis spp. in Thailand

Blastocystis spp. is one of the most common protozoa of humans and animals worldwide. The genetic diversity of Blastocystis spp. might be associated with a wide range of symptoms. However, the prevalence of each subtype is different in each country. Until now, there is no standard method for subtyping of Blastocystis spp. We developed a sequential restriction fragment length polymorphism (RFLP) analysis for the rapid differentiation of human Blastocystis subtypes. A large-scale study was also conducted to determine the subtype distribution of Blastocystis spp. in Thailand. Stool samples were collected from 1025 school-age students in four regions of Thailand. Blastocystis infections were identified by direct smear, formalin ethyl-acetate concentration technique (FECT), Boeck and Drbohlav’s Locke-Egg-Serum (LES) medium culture, and polymerase chain reaction (PCR) of small-subunit ribosomal DNA (SSU rDNA). Subtypes of Blastocystis spp. were determined by RFLP. Phylogenetic tree of partial SSU rDNA sequences of Blastocystis spp. was constructed using the Maximum Likelihood (ML) method. Out of 1025 students, 416 (40.6%) were positive for Blastocystis spp. Using two steps of RFLP reactions, we could determine subtype one–three among these students. Subtype 3 was the most common subtype (58.72%) in Thai students, followed by subtype 1 (31.2%), and subtype 2 (10.1%). Blastocystis subtype 3 was the most prevalent in all regions of Thailand. The subtype distribution of Blastocystis spp. in Thailand was different from other countries.

Molecular epidemiology of Blastocystis isolated from animals in the state of Rio de Janeiro, Brazil

The enteric protist Blastocystis is one of the most frequently reported parasites infecting both humans and many other animal hosts worldwide. A remarkable genetic diversity has been observed in the species, with 17 different subtypes (STs) on a molecular phylogeny based on small subunit RNA genes (SSU rDNA). Nonetheless, information regarding its distribution, diversity and zoonotic potential remains still scarce, especially in groups other than primates. In Brazil, only a few surveys limited to human isolates have so far been conducted on Blastocystis STs. The aim of this study is to determine the occurrence of Blastocystis subtypes in non-human vertebrate and invertebrate animal groups in different areas of the state of Rio de Janeiro, Brazil. A total of 334 stool samples were collected from animals representing 28 different genera. Blastocystis cultivated samples were subtyped using nuclear small subunit ribosomal DNA (SSU rDNA) sequencing. Phylogenetic analyses and BLAST searches revealed six subtypes: ST5 (28.8%), ST2 (21.1%), ST1 and ST8 (19.2%), ST3 (7.7%) and ST4 (3.8%). Our findings indicate a considerable overlap between STs in humans and other animals. This highlights the importance of investigating a range of hosts for Blastocystis to understand the eco-epidemiological aspects of the parasite and its host specificity.

First molecular identification and subtype distribution of Blastocystis sp. isolated from hooded crows (Corvus cornix) and pigeons (Columba livia) in Tehran Province, Iran

Blastocystis is a common intestinal parasite among humans and animals such as non-human primates, pigs, cattle, birds, amphibians, and less frequently, rats, reptiles and insects. Since Blastocystis is a widely transmissible parasite between humans and mammals or birds, it is prominent to determine whether newly secluded non-human isolates are zoonotic. There are no comprehensive studies in Iran assessing the prevalence and molecular identification of Blastocystis infection in birds, especially in pigeons and crows. So, the aim of this study was to identify Blastocystis subtypes (STs) in crows and pigeons in Tehran province, Iran, using Nested PCR-RFLP and sequencing. Overall, 300 Blastocystis isolates from birds (156 pigeons and 144 crows) were subtyped by PCR, and the homology among isolates was then confirmed by RFLP analysis of the 18S rRNA gene. The prevalence of Blastocystis infection was detected 42.9% in pigeons and 44.4% in crows. All positive pigeons were owned by ST13 (100%). Among crows, 46 samples (71.8%) like pigeons were ST13, and 13 samples (20.3%) were ST14. Five samples (7.9%) remained unknown. This study was the first report of ST13 and ST14 of Blastocystis from birds. In the present study, our data revealed a high prevalence of Blastocystis sp. in pigeon's and crow's samples and the isolates from these birds were classified into two genetically distinct STs. Therefore, birds appear to be infected with various STs. It is important to determine the phylogenetic relationships between unknown STs from these birds and the multiple STs of Blastocystis.

Zoonotic and genetically diverse subtypes of Blastocystis in US pre-weaned dairy heifer calves

Blastocystis is an emerging zoonotic pathogen with global distribution. However, limited data exist on the prevalence and genetic diversity of Blastocystis in the USA and in food animals. We conducted the first large-scale molecular investigation of Blastocystis in the USA by testing 2539 fecal samples from dairy heifer calves from 13 states. Blastocystis was detected in 73 (2.9%) fecal samples and in 10 of the 13 tested states. Molecular characterization showed a wide diversity of subtypes. Eleven subtypes were identified, seven previously reported (ST-3, ST-4, ST-5, ST-10, ST-14, ST-17, and ST-21) and four potentially novel subtypes (named ST-23 to ST-26). Zoonotic subtypes 3, 4, and 5 were found in 67% (49) of the positive specimens in this population. Our results suggest that cattle could serve as reservoirs of infection for humans and other domestic animals highlighting the potential risk of zoonotic transmission for Blastocystis.

Distribution and genetic diversity of Blastocystis subtypes in various mammal and bird species in northeastern China

Background

Blastocystis is one of the most common intestinal parasites in humans and animals worldwide. At least 17 subtypes have been identified in mammals and birds. In China, although some studies have reported the occurrence of Blastocystis in humans and animals, our understanding of the role of animals in the transmission of human blastocystosis is only superficial due to a paucity of available molecular data. The aim of the present study was to understand infection rates of Blastocystis and the distribution and genetic diversity of subtypes in various mammal and bird species in northeastern China, as well as to assess the zoonotic potential of Blastocystis isolates.

Methods

A total of 1265 fresh fecal specimens (1080 from ten mammal species and 185 from eight bird species) were collected in Heilongjiang, Liaoning and Jilin provinces of China. Each specimen was examined for the presence of Blastocystis by PCR amplification and sequence analysis of the partial SSU rRNA gene.

Results

Fifty-four specimens (4.3%) were positive for Blastocystis. Birds (7.0%) had a higher infection rate of Blastocystis than mammals (3.8%). Blastocystis was found in seven mammal species, reindeer (6.7%), sika deer (14.6%), racoon dogs (7.5%), Arctic foxes (1.9%), dogs (2.9%), rats (3.7%) and rabbits (3.3%), as well as three bird species, pigeons (2.1%), chickens (13.0%) and red crowned cranes (14.0%). Eight subtypes were identified including ST1 (n = 5), ST3 (n = 3), ST4 (n = 13), ST6 (n = 8), ST7 (n = 6), ST10 (n = 13), ST13 (n = 4) and ST14 (n = 2). 64.8% (35/54) of Blastocystis isolates belonged to potentially zoonotic subtypes.

Conclusions

To our knowledge, this is the first report of Blastocystis in reindeer (ST10 and ST13), rabbits (ST4), racoon dogs (ST3) and Arctic foxes (ST1, ST4 and ST7). The findings of potentially zoonotic subtypes suggest that the animals infected with Blastocystis might pose a threat to human health. These data will improve our understanding of the host range and genetic diversity of Blastocystis, and also help develop efficient control strategies to intervene with and prevent the occurrence of human blastocystosis in the investigated areas.

Blastocystis subtypes detected in long-tailed macaques in Thailand-Further evidence of cryptic host specificity

Blastocystis is an enteric parasitic protist with a widespread distribution in a variety of human and non-human hosts and supposedly a source of zoonotic transmission. This study aimed to determine the frequency and distribution of Blastocystis subtypes in free-ranging Macaca fascicularis (long-tailed macaques, LTMs) in Thailand. A total of 628 faecal samples were collected from free-ranging LTMs inhabiting fourteen tourist attraction sites in Thailand. Fresh faecal samples were individually cultured in Jones' medium, and Blastocystis-positive samples were subtyped using nuclear small subunit ribosomal DNA (SSU rDNA) sequencing. Two hundred and sixty-three (41.87%) samples were positive by culture, and 197 and 154 were successfully SSU rDNA-amplified and sequenced, respectively. Three subtypes (ST1, ST2, and ST3) comprising 19 alleles were observed. ST3 was the most common subtype detected (36.55%), followed by ST2 and ST1 (24.37% and 17.26%, respectively). Some subtype alleles not previously observed were identified. A couple of strains appeared similar to those found in humans as evidenced by SSU rDNA allelic profiles, while further evidence of cryptic host specificity emerged. This study provides the first data on Blastocystis subtypes in non-human primates in Thailand and confirms the trend observed in other Old-World countries with regard to the colonization rate and subtype distribution.

Prevalence and subtype distribution of Blastocystis sp. isolates from poultry in Lebanon and evidence of zoonotic potential

BACKGROUND

Blastocystis sp. is a common protozoan parasite frequently identified in the digestive tract of humans and a large variety of animal hosts worldwide, including birds. It exhibits a large genetic diversity with the identification of 17 subtypes (STs), most of them with low host specificity. ST6 and ST7 were identified in birds and suggested to represent avian STs only in the context of scarce small-scale epidemiological surveys. Moreover, these two STs also account for a significant proportion of human infections whose zoonotic origin has never been clearly confirmed. Therefore, molecular screening of Blastocystis sp. was conducted by quantitative real-time PCR for fecal samples from poultry farms and their in-contact humans from slaughterhouses in Lebanon. In parallel, a control group consisting of patients hospitalized in the same geographical area and reporting no contact with poultry was also screened for the presence of the parasite.

RESULTS

The overall prevalence of Blastocystis sp. was shown to reach around 32% in chicken samples and 65% in the farms screened. All the avian isolates were subtyped and belonged to either ST6 or ST7, with a large predominance of ST6. Fifty-four percent of slaughterhouse staff members were positive for Blastocystis sp. compared with a similar prevalence of 56% in hospitalized patients. ST3 was predominant in both human cohorts followed by either ST1 then ST2 among slaughterhouse staff or by ST2 then ST1 among hospitalized patients. ST6 was also identified in two slaughterhouse workers and not in the group of hospitalized patients. Gene sequence identity was observed between chicken and human ST6 isolates from the same slaughterhouse.

CONCLUSIONS

Our data revealed a high prevalence of Blastocystis sp. in chicken samples and confirmed that ST6 and ST7 represented avian-adapted STs. Among both human cohorts, Blastocystis sp. infection was shown to exceed 50% with a predominance of ST3. The identification of ST6 in slaughterhouse staff members confirmed the zoonotic transmission of this ST through repeated and direct contact between chickens and their handlers.

Carriage of Blastocystis spp. in travellers - A prospective longitudinal study

INTRODUCTION

A lack of prospective and longitudinal data on pre- and post-travel carriage of Blastocystis spp. complicates interpretation of a positive test post-travel. Therefore we studied dynamics of Blastocystis carriage in a cohort of Dutch travellers.

METHODS

From the prospective, multicentre COMBAT study among 2001 Dutch travellers, a subset of 491 travellers was selected based on travel destination to 7 subregions (70 or 71 travellers each). Faecal samples taken directly before and after travel were screened for Blastocystis with qPCR, followed, when positive, by sequence analysis to determine subtypes.

RESULTS

After exclusion of 12 samples with missing samples or inhibited qPCR-reactions, stool samples of 479 travellers were analysed. Before travel, 174 of them (36.3%) carried Blastocystis and in most of these, the same subtype was persistently carried. However, in 48/174 of those travellers (27.6%; CI95 20.8-36.6%) no Blastocystis or a different subtype was detected in the post-travel sample, indicating loss of Blastocystis during travel. Only 26 (5.4%; CI95 3.7%-8.0%) of all travellers acquired Blastocystis, including two individuals that were already positive for Blastocystis before travel but acquired a different subtype during travel.

DISCUSSION

This study shows that Blastocystis carriage in travellers is highly dynamic. The observed acquisition and loss of Blastocystis could either be travel-related or reflect the natural course of Blastocystis carriage. We demonstrate that the majority of Blastocystis detected in post-travel samples were already carried before travel.

Detection of Blastocystis in clinical stool specimens using three different methods and morphological examination in Jones' medium

Background:

Blastocystis was identified almost a century ago, yet its biology and pathogenicity status in humans is obscure. Studies on Blastocystis in India are scanty and are mostly microscopy based. This study compared three detection modalities to determine their efficiency in the identification of Blastocystis in human feces.

Materials and Methods:

A total of 279 stool samples were screened using microscopy, culture (Jones' medium), and polymerase chain reaction (PCR)-based methods. Among the three, PCR is considered the gold standard test for detection of Blastocystis, as it helps to authenticate the sensitivity, specificity, and kappa agreement obtained by the other two tests. The morphological features of Blastocystis were recorded at 24, 48, and 72 h. After positive morphological identification, ten samples were cultured on Löwenstein–Jensen (LJ) medium and Locke's egg slant medium.

Results:

The sensitivity and specificity determined on the basis of microscopy were 36.2% and 99.4%, respectively. On the other hand, Jones' medium showed 67.6% sensitivity and 100% specificity. Further, we documented various morphological and reproductive features of Blastocystis using various staining techniques on cultures positive in Jones' medium. In addition, we also found that LJ medium was not equally efficacious as Jones' medium in assisting the growth of Blastocystis.

Conclusions:

Although molecular diagnosis is a necessary tool for understanding the true epidemiology of Blastocystis, in laboratories devoid of molecular detection facilities, stool microscopy in conjunction with stool culture on Jones' medium could serve as the best alternative tool for the detection of Blastocystis.

Atorvastatin: In-Vivo Synergy with Metronidazole as Anti-Blastocystis Therapy

Blastocystis is an enteric Straminopile in tropical, subtropical and developing countries. Metronidazole has been a chemotheraputic for blastocystosis. Failures in its regimens were reported and necessitate new studies searching for alternative therapeutic agents. Aim of current study is to investigate potential effects of Atorvastatin (AVA) compared to the conventional chemotherapeutic MTZ in experimentally Blastocystis-infected mice. Anti-Blastocystis efficacy of AVA was evaluated parasitologically, histopathologically and by transmission electron microscopy using MTZ (10 mg/kg) as a control. Therapeutic efficacy of AVA was apparently dose-dependent. Regimens of AVA (20 and 40 mg/kg) proved effective against Blastocystis infections with high reduction in Blastocystis shedding (93.4–97.9%) compared to MTZ (79.3%). The highest reductions (98.1% and 99.4%) were recorded in groups of combination treatments AVA 20–40 mg/kg and MTZ 10 mg/kg. Blastocystis was nearly eradicated by the 20th day post infection. Genotype analysis revealed that genotype I was most susceptible, genotype III was less. Histopathologic and ultrastructural studies revealed apoptotic changes in Blastocystis and significant improvement of intestinal histopathological changes more remarkable in combinational therapy groups. Thus, the present study offers AVA as a potential candidate for Blastocystis therapy combined with MTZ.

Intestinal parasite infections in a rural community of Rio de Janeiro (Brazil): Prevalence and genetic diversity of Blastocystis subtypes

Background

Intestinal parasitic infections are considered a serious public health problem and widely distributed worldwide, mainly in urban and rural environments of tropical and subtropical countries. Globally, soil-transmitted helminths and protozoa are the most common intestinal parasites. Blastocystis sp. is a highly prevalent suspected pathogenic protozoan, and considered an unusual protist due to its significant genetic diversity and host plasticity.

Methodology/main findings

A total of 294 stool samples were collected from inhabitants of three rural valleys in Rio de Janeiro, Brazil. The stool samples were evaluated by parasitological methods, fecal culture, nested PCR and PCR/Sequencing. Overall prevalence by parasitological analyses was 64.3% (189 out of 294 cases). Blastocystis sp. (55.8%) was the most prevalent, followed by Endolimax nana (18.7%), Entamoeba histolytica complex (7.1%), hookworm infection (7.1%), Entomoeba coli (5.8%), Giardia intestinalis (4.1%), Iodamoeba butchilii (1.0%), Trichuris trichiura (1.0%), Pentatrichomonas hominis (0.7%), Enterobius vermicularis (0.7%), Ascaris lumbricoides (0.7%) and Strongyloides stercoralis (0.7%). Prevalence of IPIs was significantly different by gender. Phylogenetic analysis of Blastocystis sp. and BLAST search revealed five different subtypes: ST3 (34.0%), ST1 (27.0%), ST2 (27.0%), ST4 (3.5%), ST8 (7.0%) and a non-identified subtype.

Conclusions/significance

Our findings demonstrate that intestinal parasite infection rates in rural areas of the Sumidouro municipality of Rio de Janeiro, Brazil are still high and remain a challenge to public health. Moreover, our data reveals significant genetic heterogeneity of Blastocystis sp. subtypes and a possible novel subtype, whose confirmation will require additional data. Our study contributes to the understanding of potential routes of transmission, epidemiology, and genetic diversity of Blastocystis sp. in rural areas both at a regional and global scale.

An alternative DNA extraction method for detection of Blastocystis spp. in human fecal samples

Polymerase chain reaction (PCR) is an effective technique for diagnosis of Blastocystis infection. Notably, DNA isolation procedure is extremely critical for the PCR step. In the present study, a recently described extraction procedure, named as the "sand method" was modified and adapted for isolation of Blastocystis DNA. To evaluate its efficacy, the current method and QIAamp DNA Stool Mini Kit (Qiagen) were applied to fresh human stool samples. Our results indicated that, the mean DNA concentrations obtained by the sand method and the commercial kit were 48 and 55 ng/μl, respectively. Also, no DNA inhibitors were detected in two methods. The sand method was capable of detecting 16 parasites per 50 mg feces. DNA samples extracted by both methods were subjected to PCR. Blastocystis spp. were detected in 11 (31.4%) of 35 samples, and perfect agreement (κ: 1.000) was found between the PCR-sand method and PCR-commercial kit method. The samples that were detected positive by PCR-sand method were successfully sequenced, and Blastocystis subtypes (STs) were identified as ST3, ST2 and ST1. In conclusion, the present study indicates that the sand method provides a simple, rapid and inexpensive procedure for reliable extraction of Blastocystis DNA from stool samples.

First genotyping of Blastocystis sp. in dairy, meat, and cashmere goats in northwestern China

Blastocystis is one of the most common parasites inhabiting in small intestines of human and animals. Although its pathogenicity has been remaining controversial, the possibility of zoonotic transmission between human and animals was recognized. The goat was one of the most important economic animals supplying people with cashmere, meat, and dairy products. However, few studies were to investigate Blastocystis infection in goats. A total of 789 faecal specimens of goats (including 362 of dairy, 193 of meat and 234 of cashmere goats) were collected from multiple regions of Shaanxi province in northwestern China to investigate the colonization frequency and subtypes of Blastocystis, and to assess the zoonotic potential of these goats. The respective colonization frequencies of Blastocystis in dairy, meat and cashmere goats were 54.1% (196/362), 40.4% (78/193) and 78.6% (184/234). The prevalence of Blastocystis in pre-weaned (0-2-month) goats was significantly lower than that in goats of other age groups, and the highest colonization was observed in goats of 7-11-month age group. Sequence analysis of Blastocystis positive samples indicated the presence of seven subtypes in these goats, including six known subtypes (STs1, 3, 4, 5, 10, 14) and one possible novel subtype (isolate Sd26), with the subtype 10 as the predominant one. Additionally, zoonotic subtypes were found in dairy (ST1, ST3 and ST5) and cashmere (ST4 and ST5) goats, but not detected in meat goats. These results showed that Blastocystis is highly prevalent, widely distributed and genetically diverse in goats in Shaanxi province, northwestern China, and zoonotic potential of dairy and cashmere goats to transmit Blastocystis.

Blastocystis subtypes isolated from irritable bowel syndrome patients and co-infection with Helicobacter pylori

Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disease presenting clinically by abdominal pain with alteration of bowel habits. Although IBS has uncertain etiology, chronic gut inflammation due to persistent exposure to an infectious agent including Blastocystis sp. was proposed. The aim of this study was to detect the prevalence of Blastocystis sp. subtype (ST) isolated from stool of IBS patients and to assess Blastocystis sp. and H. pylori co-infection in IBS patients from Beni-Suef Governorate, Egypt. Stool samples were collected from 115 IBS patients, following Rome III criteria. All stool samples were microscopically examined by wet mount and permanent trichrome stain, cultured on Jones' medium with further sequencing of positive Blastocystis isolates and screened for detection of H. pylori coproantigen. Blastocystis sp. was the predominant parasite in IBS patients; it had statistical significant association with both rural residence (OR = 10) and flatulence (OR = 8.2). There was a predominance of Blastocystis sp. ST3 (81%) followed by ST1 (19%). Blastocystis culture results (19.1%) were superior than microscopy (16.5%). The majority of Blastocystis-positive IBS patients (72.7%) were co-infected with H. pylori with statistical significance; however, H. pylori was higher in Blastocystis-negative IBS patients (47/64) than in Blastocystis-positive IBS patients (17/64). Interestingly, IBS is usually associated with gut dysbiosis, while the most prevalent parasite in our IBS patients was Blastocystis sp., which is frequently found in asymptomatic individuals. Whether Blastocystis sp. is a cause or a consequence of IBS still needs further investigation, with a particular focus on correlation of IBS with different Blastocystis sp. subtypes and gut microbiomes.

Genotyping of Enterocytozoon bieneusi and Subtyping of Blastocystis in Cancer Patients: Relationship to Diarrhea and Assessment of Zoonotic Transmission

Enterocytozoon bieneusi (E. bieneusi) and Blastocystis are common pathogens responsible for diarrhea in humans, especially in immunocompromised individuals. The number of cancer patients has been increasing and diarrhea is a common clinical symptom in the treatment of cancers. To understand the prevalences and genotypes/subtypes of E. bieneusi and Blastocystis in cancer patients in China, to track the infection sources, and to explore the relationships between E. bieneusi and Blastocystis infections and diarrhea, 381 fecal specimens were collected from cancer patients. Each of them was analyzed for the presence of E. bieneusi and Blastocystis by PCR amplifying and sequencing the ITS region of the rRNA gene and the barcode region of the SSU rRNA gene, respectively. 1.3 and 7.1% of cancer patients were positive for E. bieneusi and Blastocystis, respectively. No statistical differences were observed in the infection rates between the groups by age, gender, and residence. E. bieneusi and Blastocystis were both significantly more common in cancer patients with diarrhea, and significant relationship of Blastocystis to diarrhea was found in chemotherapy group. Two E. bieneusi genotypes (D and a novel one named as HLJ-CP1) and two Blastocystis subtypes (ST1 and ST3) were identified with three novel ST1 sequences. This is the first report of occurrence and molecular characterizations of E. bieneusi and Blastocystis in cancer patients in China. E. bieneusi genotype D and Blastocystis ST1 and ST3 have been identified in humans and animals while one novel E. bieneusi genotype falling into zoonotic group 1, implying a potential of zoonotic transmission.