Blastocystis subtype 5: Predominant subtype on pig farms, Thailand

Prevalence of Blastocystis infection in humans in Türkiye: a systematic review and meta-analysis

Although Blastocystis, a protozoan, is commonly found in all species of animals and in humans, there remains a lack of clear information about its epidemiology and routes of transmission. The aim of this meta-analysis study was to determine the changes in Blastocystis prevalence and subtype distribution in humans in Türkiye according to geographical regions. Databases were searched using the Web of Science, PubMed, Scopus, EBSCO, and TRDizin to identify studies on the prevalence of Blastocystis in humans in Türkiye published from 2009 to 2023. As a result of this systematic search, 117 of 730 articles were included in the meta-analysis. The pooled prevalence of human Blastocystis infection in Türkiye was 13.08%. The prevalence of the pool was higher in the Black Sea region, which is the most humid region in Türkiye, than in other regions. Blastocystis subtypes were identified in a total of 885 positive samples. The most common subtypes (ST) in Türkiye were ST3, ST1 and ST2, respectively. In addition to these ST4, ST5, ST6 and ST7 were also detected in humans in Türkiye. In conclusion, the prevalence of Blastocystis in humans is high in Türkiye, especially in the Black Sea region.

Prevalence and subtypes of Blastocystis in wild rodents from three provinces in China

Introduction

Blastocystis is one of the most critical intestinal protozoans in various hosts, including humans and mice. To determine the status of Blastocystis infection in wild rodents in China.

Methods

A total of 344 faecal samples were collected from seven wild rodent species from three provinces, and the small subunit ribosomal RNA (SSU rRNA) genes of Blastocystis were amplified to determine their prevalence and subtypes.

Results

Of the 344 samples, 54 (15.70%) were detected as Blastocystis-positive. The prevalence of Blastocystis was 26.14% (40/153), 7.95% (7/88), and 6.80% (7/103) in wild rodents from Hunan Province, Yunnan Province, and Guangxi Province, respectively. The prevalence of Blastocystis in different wild rodent species varied from 0.00% (0/13) in Mus musculus to 40.00% (2/5) in Rattus rattus sladeni. The prevalence of Blastocystis in samples from the lake beach area (27.40%, 40/146) was significantly higher than in those from the mountain (6.80%, 7/103) and field regions (7.37%, 7/95). The prevalence in different seasons was 26.14% in summer (40/153), 7.95% in autumn (7/88), and 6.80% in winter (7/103). Moreover, a total of two Blastocystis subtypes were identified in the investigated wild rodents, including ST4 and ST5.

Discussion

The present study discovered the existence of Blastocystis infection in Rattus favipectus, Microtus fortis, Apodemus agrarius, Bandicota indica, Rattus rattus sladeni, and Rattus losea, expanding the host range of this parasite. The findings also demonstrate that wild rodents may be an important potential infection source for Blastocystis infection in humans and other animals.

Molecular detection and genotyping of Dientamoeba fragilis and Blastocystis sp. in housefly Musca domestica (Diptera: Muscidae): first report for Dientamoeba fragilis

Dientamoeba fragilis and Blastocystis sp. are single-celled protozoan parasites of humans and animals. Although they are found in the intestines of healthy hosts, the pathogenicity of them is still unclear. To date, there is no report on D. fragilis and only two studies (without subtyping) on the occurrence of Blastocystis sp. in Musca domestica. In this study, fly samples were collected from livestock farms and their surroundings in the Kirsehir province (Central Anatolia Region) of Türkiye from May to August 2023. A total of 150 microscopically identified M. domestica samples were analyzed for the detection of D. fragilis and Blastocystis sp. molecularly. The overall prevalence of Blastocystis sp. and D. fragilis in M. domestica was determined to be 3.3% (5/150) and 8.0% (12/150), respectively. The SSU rRNA gene sequences of the isolates indicated genotype 1 of D. fragilis. Eleven isolates were identical and represented a single isolate (KAU-Dfrag1). BLAST analysis of KAU-Dfrag1 indicated identity with the isolates reported from humans, cattle, sheep, and budgerigars. The other isolate (KAU-Dfrag2) was polymorphic at two nucleotides from KAU-Dfrag1 and three nucleotides from known genotypes from GenBank and represented a variant of genotype 1. The Blastocystis sp. isolates were found to be identical and represent a single genotype (KAU-Blast1). BLAST analysis revealed that the KAU-Blast1 genotype belonged to the potentially zoonotic subtype 5 (ST5) and exhibited the highest genetic identity (ranging from 99.4 to 99.6%) with pigs, cattle, and sheep from different countries. Our study provides the first data on the molecular prevalence, epidemiology, and genotypic characterization of D. fragilis and Blastocystis sp. in M. domestica.

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.

Systematic Review and Meta-Analysis: Epidemiology of Human Blastocystis spp. Infection in Malaysia

Blastocystis spp. is a unicellular enteric protozoan parasite in humans with a controversial role in disease etiology. It is common in developing countries among immunocompromised patients and people who have close contact with animals. In this study, we have systematically reviewed previous studies on the distribution and genotypes of human Blastocystis infection in Peninsular Malaysia. Studies examining the prevalence of Blastocystis in diverse demographics, including rural, urban, comorbid conditions, and high-risk populations, were taken into consideration. The infection has been reported in nine states; the total percentage of infection was 17.8% (1671/9397), with the most cases in Pahang (27.3%) and the least in Johor (3.4%). Molecular studies revealed the presence of six subtypes: ST1, ST2, ST3, ST4, ST5, and ST6. ST3 was reported as the predominant subtype in all the states, with a prevalence of 54.7% (338/618). The findings provide greater clarity on the epidemiology of Blastocystis in Malaysia, which will help in policy making towards planning and strategizing control measures against the parasite.

Blastocystis in tap water of a community in northern Thailand

Blastocystis is the most common protist in the gut of humans and other animals having global distribution. Occasionally, this organism has also been reported in the environment. Transmission to humans occurs via the fecal-oral route, while water also comprises a transmission route. Blastocystis has been commonly found in rivers, lakes, and wells. Nonetheless, there is limited data about the prevalence and genetic diversity of Blastocystis in tap water. The main aim of this study was to examine the presence of Blastocystis subtypes in tap water (n=20) in a community in northern Thailand. Molecular characterization using the small subunit ribosomal RNA was used to screen for Blastocystis and identify the diversity of subtypes in samples. The overall prevalence was 30% with only subtype three (ST3) encountered in the tap water. These results indicate that tap water has a potential role in the transmission of this subtype in the studied community. Further investigations should focus on expanding sampling to include additional housing complexes and screening for Blastocystis in humans who are exposed to this water.

Identification and Genetic Characterization of Blastocystis Species in Patients from Makkah, Saudi Arabia

Background

Blastocystis species (sp.) are gastrointestinal protozoan parasites with high prevalence rates worldwide. Blastocystis sp. show extensive genetic diversity with 17 different subtypes (STs) described to date. A few studies have investigated the prevalence and STs of Blastocystis sp. in Makkah, Saudi Arabia. Therefore, we aimed in this study to identify and characterize subtypes of Blastocystis sp. in the City of Makkah, Saudi Arabia.

Methods

Stool samples were collected from 140 patients who presented to King Abdulaziz Hospital, Hera General Hospital and Modern Medical Center in Saudi Arabia. Different microscopic examination methods of patients’ stools and molecular analyses (using primers targeting SSU rRNA gene) were performed to identify and characterize STs of Blastocystis sp.

Results

Our microscopic examination of stool samples showed that 96/140 patients (68.6%) had Blastocystis sp. infection. Clinical examination of infected patients revealed that 81 patients were symptomatic, whereas 15 were asymptomatic. Next, we isolated DNA from Blastocystis sp.-positive stool samples followed by PCR amplification of small-subunit ribosomal RNA (SSU rRNA) gene and sequence analysis. Our sequence analysis showed that subtype 3 (ST3) was the most prevalent (53.13%) followed by subtype 1 (ST1) (45.83%), whereas subtype 2 (ST2) was the least prevalent (1.04%). Moreover, our results showed that all three STs resulted in more symptomatic than asymptomatic cases. Finally, we identified novel haplotypes which comprised of 8 ST3, 6 ST1, and one ST2 haplotypes.

Conclusion

Our identification of several haplotypes in patients’ stools confirms the genetic diversity of Blastocystis sp. and may explain the reported low host specificity and differential pathogenicity of Blastocystis sp. We believe that additional molecular epidemiological and genomic studies are needed to understand the prevalence and pathogenicity of different subtypes in humans and animal hosts.

Molecular characterization of Blastocystis sp. in Chinese bamboo rats (Rhizomys sinensis)

Blastocystis sp., a parasitic eukaryote, widely colonizes the intestines of humans and a large number of animals, including rodents and lagomorphs. More than 30 million bamboo rats (Rhizomys sinensis) are farmed in China as a source of meat for human consumption. However, there have been no published articles on Blastocystis infection in Chinese bamboo rats prior to the present study. Herein, 480 fresh faecal samples were collected from R. sinensis on six farms located in four cities (Wugang, Chenzhou, Huaihua and Jishou) in Hunan Province, south-central China, and were examined for Blastocystis infection using polymerase chain reaction (PCR) targeting the small subunit ribosomal RNA (SSU rRNA) gene. The total prevalence of Blastocystis in R. sinensis was 4.58% (22/480), and significant differences in prevalence were detected among four age groups (<6 months, 6–12 months, 12–24 months and >24 months), with the highest prevalence (7.81%) in rats aged 6–12 months but with no positive samples in rats over 24 months. All farms, except for one in Jishou, were positive for Blastocystis infection, with the prevalence ranging from 1.80% to 7.27%. Sequence and phylogenetic analyses revealed two potentially zoonotic subtypes (namely ST4 and ST5) in these rodents, with ST4 predominant in all except one farm in Huaihua. Seven and five sequence types were identified within ST4 and ST5, respectively. This is the first report of Blastocystis infection in Chinese bamboo rats and the findings suggest the potential of R. sinensis to transmit Blastocystis to humans.

Prevalence of Blastocystis and its association with Firmicutes/Bacteroidetes ratio in clinically healthy and metabolically ill subjects

BACKGROUND

Blastocystis is a typical anaerobic colon protist in humans with controversial pathogenicity and has relation with alterations in the intestinal microbiota composition (dysbiosis), whose eventual indicator is the Firmicutes/Bacteroidetes ratio (F/B ratio); this indicator is also linked to complications such as diabetes, obesity, or inflammatory bowel disease. The present study investigated the prevalence of Blastocystis and its association with Firmicutes/Bacteroidetes ratio in healthy and metabolic diseased subjects.

METHODS

Fecal and blood samples were collected consecutively from 200 healthy subjects and 84 subjects with metabolic disease; Blastocystis and its most frequent subtypes were identified by end-point PCR and the two most representative phyla of the intestinal microbiota Firmicutes and Bacteroidetes by real-time PCR.

RESULTS

The prevalence of Blastocystis in healthy subjects was 47.0, and 65.48% in subjects with metabolic disease; the most prevalent subtype in the total population was ST3 (28.38%), followed by ST1 (14.86%), ST4, ST5, and ST7 (each one of them with 14.19% respectively), and finally ST2 (8.78%). The low F/B ratio was associated with the prevalence of Blastocystis in the two cohorts FACSA (OR = 3.78 p < 0.05) and UNEME (OR = 4.29 p < 0.05). Regarding the subtype level, an association between the FACSA cohort ST1 and ST7 with low Firmicutes/Bacteroidetes ratio was found (OR = 3.99 and 5.44 p < 0.05, respectively).

CONCLUSIONS

The evident predatory role of Blastocystis over Firmicutes phylum was observed in both cohorts since the abundance of bacterial group's Bacteroidetes increases in the groups colonized by this eukaryote and, therefore, may have a beneficial effect.

Subtype analysis and prevalence of mixed subtype infection of Blastocystis in farmed pigs from Chiba Prefecture, Japan

Blastocystis is an intestinal eukaryotes found in a wide range of animals and in the human population globally. Blastocystis is reported in domestic pigs, with subtype (ST) 5 being the dominant ST, followed by ST1 and ST3. The common method used for ST identification in pigs is PCR-sequencing, which often results in underestimation of the prevalence of mixed infections. Here, we aimed to investigate the ST distribution and the prevalence of mixed ST infection of Blastocystis in pigs from Chiba Prefecture in eastern Japan. A total of 82 fecal samples positive for Blastocystis were collected from two different farms, A and B. PCR was performed with subtype-specific primers, ST1, ST2, ST3, and ST5. The prevalence of single ST5 infection was 37.8% (31/82), whereas mixed infection with ST5 and other STs was 57.3% (47/82). A high percentage of single ST5 infection was observed in sows, piglets, and weaners from farm A (13/15, 86.7%), whereas mixed infection of ST5 and other STs, ST1 and ST3, was observed in 3-5-month-old grower pigs (15/18, 83.3%). Similarly, in farm B, the majority of sows and piglets under 1 month of age showed a single ST5 infection (12/17, 70.6%), whereas weaner, grower, and finisher pigs showed mixed infections with ST5 and other STs, ST1, ST2 and ST3 (27/28, 96.4%). In domestic pigs, diet and rearing environment changes dramatically over the course of animal's lifetime, which may have caused this difference in the prevalence of mixed ST infection among different age groups.

Molecular prevalence and subtype distribution of Blastocystis sp. in Asia and in Australia

Blastocystis is a prevalent protozoan parasite reported in humans, animals, and environmental samples. Over the past decade, numerous studies have investigated the prevalence and subtype distribution of Blastocystis sp. alongside with its genetic and biochemical features. However, studies on subtype distribution of this protozoan in humans, animals, and environmental samples represent the potential transmission routes. In this review, we evaluated studies performed in Asian countries and in Australia to provide an overview of environmental factors on the prevalence and subtype distribution of Blastocystis sp. among humans, animals, and the environment.

The Coexistence of Blastocystis spp. in Humans, Animals and Environmental Sources from 2010-2021 in Asia

Blastocystis spp. are controversial unicellular protists that inhabit the gastrointestinal tract of humans and a wide range of animals worldwide. This review provides an overview of the prevalence and distribution of Blastocystis spp. and their subtypes throughout Asia. Research articles reporting on the presence of Blastocystis spp. in locations within Asia, between 1 January 2010, and 10 May 2021, were obtained from Scopus, PubMed, and Google Scholar. In 427 articles, the prevalence of Blastocystis spp. in 31 countries within the last decade was revealed. Isolates were found in humans, various mammals, birds, reptiles, insects, water sources, vegetables, and ambient air. Prevalence of Blastocystis spp. varied widely across host categories. Subtypes identified throughout Asia were STs 1-14, and ST18-22 (novel subtypes). ST1, ST2, ST3, ST4 were the most frequently isolated in humans; ST5 in pigs; ST10 and ST14 in goats, sheep, and cattle; and ST6 and ST7 in chickens. ST1 and ST3 were most common in water samples. ST1, ST2, ST3, ST4, ST5 and ST6 were shared by humans, animals, and water sources. There is a growing interest in the study of Blastocystis spp. and their subtypes in Asia. Due to the isolation of Blastocystis spp. from biotic and abiotic sources in Asia, the application of the One Health (OH) approach to the study of Blastocystis spp. is proposed for improved perception of this organism.

Prevalence and Subtype Distribution of Blastocystis sp. in Diarrheic Pigs in Southern China

Blastocystis sp. is a common pathogen that infects the intestines of humans and animals, causing a threat to public health. However, little information on the prevalence and subtypes of Blastocystis sp. in diarrheic pigs in China is available. Herein, 1254 fecal samples were collected from diarrheic pigs in 37 intensive pig farms in Hunan, Jiangxi, and Fujian provinces in southern China, and the prevalence and subtypes of Blastocystis sp. were investigated. Blastocystis sp. was detected by PCR assay, which amplified the small subunit rRNA (SSU rRNA) gene. Overall prevalence of Blastocystis sp. was 31.4% (394/1254), including 21.5% (66/307), 33.1% (99/299), 58.9% (56/95), and 31.3% (173/553) in suckling piglets, weaned piglets, fattening pigs, and sows, respectively. Moreover, age and region factors were significantly related to prevalence of Blastocystis sp. (p < 0.05). Four Blastocystis sp. subtypes were identified, including ST1, ST3, ST5, and ST14. The preponderant subtype was ST5 (76.9%, 303/394). To our knowledge, ST14 was firstly found in pigs in China. The human-pathogenic subtypes (ST1, ST3, ST5, and ST14) that were observed in this study indicate a potential threat to public health. These findings provided a new sight for studying the genetic structure of Blastocystis sp.

Global prevalence, subtypes distribution, zoonotic potential, and associated risk factors of Blastocystis sp. in domestic pigs (Sus domesticus) and wild boars (Sus scrofa): A systematic review and meta-analysis

The intestinal parasite Blastocystis sp. is a widely distributed protist among humans and various animal hosts, with significant prevalence in developing countries. Due to the zoonotic nature of its subtypes (STs), we aimed at global estimation of the prevalence, STs distribution, zoonotic potential, and associated risk factors of Blastocystis sp. infection in domestic pigs (Sus domesticus) and wild pigs/wild boars (Sus scrofa). The study was designed and conducted in 2021 via searching articles in PubMed, Scopus, Google Scholar, and Web of Science databases, based on the PRISMA checklist, and meta-analysis was done using a random-effects model to calculate the weighted estimates and 95% confidence intervals (95% CIs). Totally, 43 papers (47 datasets) reported data on 7977 examined pigs in 24 countries with a total prevalence of 50.9% (95% CI: 42.8-59%). In details, prevalence was higher among domestic pigs [52.4% (95% CI: 43.9-60.7%)] than wild boars [31.2% (95% CI: 11.2-62%)], but is poorly statistically supported as far as the CIs largely overlap. Out of 28 reported STs, nine (ST1-ST7, ST10, and ST15) were reported from domestic pigs, while six (ST1, ST3-ST5, ST8, and ST15) had been isolated from wild boars. Among nine zoonotic STs (ST1-ST8, and ST12), all were identified in examined swine populations, except for ST12. As well, ST1 and ST5 were probably the most frequently circulating STs among these animals. In addition, male and older pigs showed higher Blastocystis sp. infection. Altogether, Blastocystis epidemiology and the distribution of its related STs in pigs is still open to question and requires more extensive studies, especially in the neglected regions of the world.

Prevalence, Molecular Characterization and Risk Factors of Blastocystis sp. from Farmed Pigs in Yunnan Province, Southwestern China

PURPOSE

Blastocystis is an enteral eukaryote that omnipresent existence in animals and humans global. The objective of the current study investigated the frequency and subtypes to evaluate risk factors for Blastocystis infection in pigs in southwestern China.

MATERIALS AND METHODS

The 866 fecal samples were collected from farmed pigs in Yunnan province, which were determined by the molecular method of the nested PCR and phylogenetic analysis established on the small subunit rDNA (SSU rDNA) gene fragment.

RESULTS

A total of 433 specimens were detected Blastocystis positive, and the prevalence of is 50.0% (433/866). The significant differences in prevalence were also observed in pigs from regions (P < 0.01, df = 8, χ² = 29.17) and age groups (P < 0.01, df = 2, χ² = 66.6). Older pigs had more Blastocystis infection than younger ones. Moreover, three zoonotic subtypes were identified by DNA sequence analysis, included ST1 (7.39%, 32/433), ST3 (4.39%, 19/433) and ST5 (88.22%, 382/433).

CONCLUSIONS

The results suggested a high prevalence and diversified subtypes in farmed pigs in Yunnan province, southwestern China, which indicated pigs are most likely to potential reservoirs and zoonotic transmission of Blastocystis for human infection. To our knowledge, the study is the first large-scale systematic statement of Blastocystis colonization in Yunnan province, Southwestern China, which contributed to the in-depth study of genetic characteristics and prevention, control and treatment of Blastocystis in pigs in Yunnan province and other regions.

Prevalence and Subtype Distribution of Blastocystis Infection in Patients with Diabetes Mellitus in Thailand

Diabetes mellitus (DM) is a major global public health problem with an increasing prevalence. DM increases the risk of infections caused by bacteria, fungi, viruses, and parasites. We examined the prevalence, subtypes, and risk factors of Blastocystis infection in patients with and without DM in central Thailand. Stool samples and questionnaires were obtained from 130 people in the DM group and 100 people in the non-DM group. Blastocystis infection was identified via a nested polymerase chain reaction and subtyped via sequencing of the partial small-subunit ribosomal RNA (SSU rRNA) gene. Analysis of potential risk factors was conducted via binary logistic regression. The overall prevalence of Blastocystis infection was 10.8%, including rates of 9% and 12.3% in the non-DM and DM groups, respectively. The most prevalent subtype was ST3, followed by ST1, and ST4. Factors that potentially increased the risk of Blastocystis infection include patients being >65 years old, the presence of DM, a DM duration of ≥10 years, a low level of education, and animal ownership. In conclusion, this is the first study of Blastocystis infection in DM, and a high prevalence was found among this population. Therefore, health education promoting sanitation and hygiene is necessary to reduce and prevent infection in the community.

First detection of Blastocystis sp. in pigs in Slovakia and in Europe

Blastocystis sp. is a single-cell microorganism occurring in the gastrointestinal tract of humans and various animals and is distributed worldwide. Blastocystis exhibits extensive genetic diversity of 28 subtypes (STs) based on the small subunit ribosomal RNA (SSU rRNA) gene. In this study, the genetic diversity and zoonotic potential of Blastocystis were evaluated using pig faecal samples from two farms in Slovakia. Blastocystis spp. were detected in pigs intended for distribution and consumption. ST 5 subtype was identified in all positive samples and age categories with a prevalence of 12%. However, the prevalence on one of the farms was up to 28.6%. This is the first study of Blastocystis in pigs carried out in Slovakia. Although a number of samples obtained was small, the identified subtype of ST5 Blastocystis sp. occurs in humans and animals. It may have zoonotic potential and therefore may be a risk factor due to the close contact between humans and pigs on the breeding farms.

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.

First Report of Blastocystis Infection in Pigs from Large Farms in Xinjiang, China

Blastocystis is a common intestinal protozoan in humans and various animals worldwide. A few studies have reported the genetic characterization of Blastocystis in pigs in China, but no epidemiological data are available from the Xinjiang Uygur Autonomous Region. In this study, 801 fecal samples were collected from seven scale pig farms in Xinjiang and tested by polymerase chain reaction and sequence analysis of the partial SSU rRNA gene. The average infection rate of Blastocystis was 21.7% (174/801), with 7.1% in preweaning piglets, 10.0% in postweaning piglets, 31.8% in fattening pigs, and 41.9% in sows (χ²  = 104.89; P < 0.01). Blastocystis subtypes ST1 (7/174), ST3 (2/174), and ST5 (165/174) were identified, with subtype ST5 being predominant in each of the pig farms and in each of the age groups. ST3 and ST5 were identified in preweaning piglets, and ST1, ST3, and ST5 were identified in postweaning piglets. In contrast, only the subtype ST5 was observed in fattening pigs and sows. Genetic polymorphisms were observed at the intrasubtype level, including two variations of ST1 (ST1A, ST1B), and seven of ST5 (ST5A to ST5G), by sequence alignment analysis and phylogenetic analysis. More studies are needed to elucidate the transmission and public health significance of Blastocystis in pigs in various areas.

First Report on the Occurrence and Subtypes of Blastocystis in Pigs in Poland Using Sequence-Tagged-Site PCR and Barcode Region Sequencing

Blastocystis is an enteric microorganism commonly found in humans and animals worldwide. Its pathogenic role in humans and transmission patterns has not been fully explained. However, nine subtypes (ST1-8, ST12) are considered as potentially zoonotic. Studies from various regions of the world show that pigs are mainly infected with ST5. Although pigs are important farmed animals in Poland, the question of Blastocystis infection in these animals has not yet been investigated. Herein, 149 pig stool samples from 10 Polish pig farms were analyzed using sequence-tagged-site PCR and barcode region sequencing. The percentage of samples in which Blastocystis was identified using each method separately was similar: 38.25% and 37.58%, respectively. However, the percentage of positive results obtained by combining both methods was 46.97%, which means that, depending on the method used, the number of undetected samples varied between 8.72% and 9.39%. This shows the methodological limitations of up-to-date molecular approaches commonly used in Blastocystis research. A moderate infection rate (44.4-50%) observed in different pig age groups with a vital predominance of ST5 (94.28%) in every age group shows that pigs are a likely natural host of ST5. A small percentage of mixed infections, namely ST5/ST1 (5.26%), ST5/ST3 (1.75%), and ST3/ST1 (1.75%), was observed only in animals of older age, suggesting that ST3 and ST1 can be acquired by pigs during contact with humans. This study provides the first data on the prevalence and Blastocystis subtypes (STs) distribution in pigs in Poland. The results also highlight the need for the development of new methods capable of detecting highly genetically diverse Blastocystis isolates and mixed infections.

Assessment of the subtypes and the zoonotic risk of Blastocystis sp. of experimental macaques in Yunnan province, southwestern China

Blastocystis is an enteral eukaryote with an omnipresent existence in animals and humans globally. Animals have been proposed to be a major reservoir for the transmission of Blastocystis to individuals due to their high prevalence and large amount of zoonotic subtypes. However, limited data on Blastocystis infection in experimental macaques in China exists. The objective of the current study was to investigate the frequency and subtypes of Blastocystis infection in macaques in southwestern China. A total of 505 fecal samples were collected from experimental macaques in Yunnan province and were analyzed by nested PCR and phylogenetic analyses on the basis of small subunit rRNA (SSU rRNA) gene fragments. A total of 235 specimens were positive for Blastocystis sp., and the prevalence of Blastocystis sp. was 46.5% (235/505). Significant differences in prevalence were also observed among the various species of macaques (P < 0.0133, df = 2, χ² = 8.64) and the different feed types (P < 0.0093, df = 1, χ² = 6.77). Moreover, three zoonotic subtypes, ST1, ST3, and ST5, were identified by DNA sequence analysis. There were mainly single subtype infections with some mixed subtype infections, and the predominant subtype was ST3. The results suggested a high prevalence and diversified subtypes in macaques in Yunnan province, southwestern China. Macaques are likely to be potential reservoirs capable of zoonotic transmission of Blastocystis sp. to humans. To our knowledge, this study is the first large-scale systematic analysis of Blastocystis sp. colonization in Yunnan province in the subtropics of China; these results contribute to the in-depth study of genetic characteristics and the prevention, control, and treatment of Blastocystis sp. in macaques in Yunnan province and other regions.

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.