Molecular identification of Blastocystis sp. subtypes in water samples collected from Black sea, Turkey

Predominance of the Blastocystis subtype ST5 among free-living sympatric rodents within pig farms in China suggests a novel transmission route from farms

Blastocystis is a parasitic protist that can infect humans and various domestic and wild animals. However, there is limited research on the prevalence of this parasite among rodents, particularly those living in pig farm settings. Therefore, to investigate the occurrence, molecular characterization, and zoonotic potential of Blastocystis among rodents within pig farm environments, we conducted an investigation of 227 rodents and shrews from 34 pig farms located in Henan, Shaanxi, and Shanxi provinces of China using nested PCR of the SSU rRNA gene of Blastocystis. The potential transmission and public health implications were also assessed from a One Health perspective. Blastocystis was detected in 86 (37.9%) fecal samples. The highest infection rate was observed among Ruttus norvegicus (73.7%, 42/58), followed by Ruttus tanezumi (30.1%, 41/136), and Mus musculus (12.0%, 3/25). However, it was not detected among individuals with Apodemus agrarius (n = 1) and Crocidura shantungensis (n = 7). Five known zoonotic Blastocystis subtypes (ST1-ST5) were identified, with ST4 (51.2%, 44/86) and ST5 (40.7%, 35/86) being the predominant ones, followed by ST1 (3.5%, 3/86), ST3 (3.5%, 3/86), and ST2 (1.2%, 1/86). ST4 was prevalent among R. norvegicus (83.3%, 35/42), while ST5 dominated R. tanezumi (70.7%, 29/41). Furthermore, ST5 exhibited the widest distribution at pig farm level, accounting for 65.0% (13/20) of Blastocystis-positive pig farms. This investigation presents the first documented Blastocystis infection in R. tanezumi and M. musculus, highlighting the predominant presence of the zoonotic ST5 subtype in rodents for the first time. The results demonstrate that sympatric rodents can serve as natural reservoirs for Blastocystis and play a role in its transmission. These findings provide information on the dynamics of rodent transmission and emphasize the potential public health threat posed by zoonotic Blastocystis subtypes spillover from pig farms.

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

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

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.

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.

A longitudinal study of Blastocystis in dairy calves from birth through 24 months demonstrates dynamic shifts in infection rates and subtype prevalence and diversity by age

Blastocystis is a common microeukaryotic intestinal parasite in humans and other animal hosts globally. However, no large-scale longitudinal study has ever been conducted for Blastocystis. To understand patterns of infection prevalence and subtype diversity and their relationship with host age, we have conducted the most comprehensive longitudinal study of Blastocystis infection ever performed. Dairy calves from a herd located in Maryland, USA, were followed from birth through 24 months of age, and 990 individual fecal samples from 30 calves were collected over the study period, representing three age groups (pre-weaned, post-weaned, and heifer). All samples were screened for Blastocystis via PCR, and subtype determination was performed using next-generation amplicon sequencing. Associations between age group and infection status were assessed using logistic regression analyses. Blastocystis infection prevalence increased with time, significant associations were observed between age groups and infection risk, and a cumulative prevalence of 100% was observed among the study population during the 24-month period. Thirteen previously reported subtypes (ST1-6, ST10, ST14, ST21, ST23-26) and one potentially novel subtype were observed. Diversity within ST10 supports the need for division of the subtype into new subtype designations. Associations between subtype and age group were explored, and relationships between subtypes and infection chronicity are described. While subtype diversity increased with age in the study population, distinct patterns of individual subtype prevalence and chronicity were observed, supporting the importance of subtype discrimination in studies of host infection and disease. The data from this study represent a significant advance in our understanding of Blastocystis infection dynamics within a single host population over time and can be used to inform future studies of Blastocystis epidemiology in both humans and other animal hosts.

Blastocystis subtypes in raw vegetables from street markets in northern Thailand

Blastocystis is a stramenopile protist of controversial pathogenicity. The organism colonizes a broad range of vertebrate and invertebrate hosts. Blastocystis has also been found in the environment both in water and soil. Several routes of transmission have been proposed including human to human, animal to human, and via contaminated food and water. In recent years, the presence of Blastocystis in vegetables has started to be explored. However, most studies have focused on microscopic detection. Moreover, works of this type from Asia are barely available. Hence, the aim of this preliminary study was to examine the occurrence of Blastocystis in raw vegetables sold in markets in northern Thailand. Fresh produce (n = 20) commonly used in Thai cuisine (Lanna) was purchased from two street markets and screened for Blastocystis using qPCR. Blastocystis was detected in 45% of the samples with the dominant subtype being ST3. Produce growing underground, such as galangal, carrot, and beetroot, were positive for the organism suggesting soil or inadequately composted manure as the source of contamination. To our knowledge, our study is the first to perform subtyping of Blastocystis in vegetables. Our results hint toward fresh produce being a, as yet, not widely explored, transmission route of Blastocystis in the studied community. Looking forward, large-scale investigations on the prevalence of this and other organisms under the One Health umbrella should be undertaken.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

Global prevalence and subtype distribution of Blastocystis sp. in rodents, birds, and water supplies: A systematic review and meta-analysis

Animals such as rodents and birds may play a key role in the distribution of Blastocystis sp., either as introducers of the parasite into the water or as receptors of an infection already established in the water. Hence, we aimed to evaluate the prevalence and subtype distributions of Blastocystis sp. in rodents, birds, and water supplies at a global scale through a systematic review and meta-analysis approach. The standard protocol of preferred reporting items for systematic reviews and meta-analyses (PRISMA) statements were applied. Eligible prevalence studies on Blastocystis sp. in rodents, birds, and water supplies, published between 1 January 2000 and 20 January 2022 were collected using a systematic literature search in online databases (Scopus and Web of Science) and search engines (PubMed and Google Scholar). Inclusion and exclusion criteria were followed. The point estimates and 95% confidence intervals (CI) were calculated using a random-effects model. The variances between studies (heterogeneity) were computed by I2 index. In total, 20 articles (24 datasets) for birds, 18 articles (18 datasets) for rodents, and 10 articles (12 datasets) for water supply were included for the final meta-analysis. The pooled prevalence of Blastocystis sp. in birds, rodents, and water was estimated to be 29% (95% CI 12-47%), 18% (95% CI 12-23%), and 10% (95% CI 6%-15%), respectively. Considering the subtypes, Blastocystis sp. with subtypes ST7 in birds, ST4 in rodents, and ST1 in water supplies were the highest reported subtypes. The present results highlight the role of birds, rodents, and water as a reservoir for human-infected Blastocystis sp. Therefore, this global estimate could be beneficial for preventive and control measures.

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.

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.

First report of Blastocystis sp. subtypes in natural water bodies in north-western Poland: a one-year monitoring

Studies on the presence of Blastocystis subtypes in water samples are far less numerous compared with stool samples. The main aim of this study was to examine the occurrence of Blastocystis subtypes in 36 natural water bodies in north-western Poland in the period from winter 2009 to autumn 2010. Single PCR with the use of Blast 505-532/Blast 998-1017 set of primers was used to detect Blastocystis DNA in the obtained water samples. Sequencing of the obtained amplicons revealed the presence of ST1 and ST3 subtypes in five of the 36 (13.9%) examined water bodies within 1 year period. Further examinations with the use of new samples are needed in order to check if Blastocystis occurs in the examined water bodies at the present time, however, the risk of infection should be taken into consideration.

Comparative study of the intestinal parasitism profiles between communities across the 5 municipalities of the Barranquilla metropolitan area, Colombia

Objectives

The aim of this study was to compare the rate of parasitism and intestinal parasitism profiles of children who live in relatively proximal communities across the 5 municipalities of the Barranquilla metropolitan area, Colombia.

Methods

In total, 986 fecal samples from children aged 1 to 10 were analyzed using a direct method (physiological saline and lugol) and the zinc sulfate flotation technique. A comparative analysis of the parasitism profiles between sampling locations (7 schools and 3 health centers providing growth and development services) was conducted using principal component analysis (PCA). The presence of Taenia solium antibodies was evaluated by the enzyme-linked immunosorbent assay method in 269 serum samples from the same group of children.

Results

The overall prevalence of intestinal parasitism was 57.6% (range, 42.1%–77.6%) across the sampling areas. The prevalence of helminthiasis was between 4.1% and 23.7%, and that of intestinal protozoa was between 38.2% and 73.5%. PCA showed that the parasite profiles of each sampling location shared no common characteristics. A total of 3.0% of the serum samples were positive for T. solium antibodies.

Conclusion

The intestinal parasitism profiles between relatively proximal sampling locations with similar geographic conditions were vastly different, indicating the need to study each small ecological niche on a localized scale to develop more cost-effective interventions for controlling intestinal parasitism.

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.

Molecular Detection and Characterization of Blastocystis sp. and Enterocytozoon bieneusi in Cattle in Northern Spain

Some enteric parasites causing zoonotic diseases in livestock have been poorly studied or even neglected. This is the case in stramenopile Blastocystis sp. and the microsporidia Enterocytozoon bieneusi in Spain. This transversal molecular epidemiological survey aims to estimate the prevalence and molecular diversity of Blastocystis sp. and E. bieneusi in cattle faecal samples (n = 336) in the province of Álava, Northern Spain. Initial detection of Blastocystis and E. bieneusi was carried out by polymerase chain reaction (PCR) and Sanger sequencing of the small subunit (ssu) rRNA gene and internal transcribed spacer (ITS) region, respectively. Intra-host Blastocystis subtype diversity was further investigated by next generation amplicon sequencing (NGS) of the ssu rRNA gene in those samples that tested positive by conventional PCR. Amplicons compatible with Blastocystis sp. and E. bieneusi were observed in 32.1% (108/336, 95% CI: 27.2–37.4%) and 0.6% (2/336, 95% CI: 0.0–1.4%) of the cattle faecal samples examined, respectively. Sanger sequencing produced ambiguous/unreadable sequence data for most of the Blastocystis isolates sequenced. NGS allowed the identification of 10 Blastocystis subtypes including ST1, ST3, ST5, ST10, ST14, ST21, ST23, ST24, ST25, and ST26. All Blastocystis-positive isolates involved mixed infections of 2–8 STs in a total of 31 different combinations. The two E. bieneusi sequences were confirmed as potentially zoonotic genotype BEB4. Our data demonstrate that Blastocystis mixed subtype infections are extremely frequent in cattle in the study area. NGS was particularly suited to discern underrepresented subtypes or mixed subtype infections that were undetectable or unreadable by Sanger sequencing. The presence of zoonotic Blastocystis ST1, ST3, and ST5, and E. bieneusi BEB4 suggest cross-species transmission and a potential risk of human infection/colonization.

Molecular identification and subtype distribution of Blastocystis sp. in farm and pet animals in Turkey

A total of 1340 fresh fecal samples from farm and pet animals in Central Anatolia and the Middle Black Sea Region of Turkey were investigated using a PCR assay targeting the SSU rRNA of Blastocystis sp. An overall Blastocystis sp. prevalence of 19.4% (183/940) was found in farm animals, including cattle, sheep, water buffaloes, and chickens. Fecal samples of dogs, cats, and horses were negative. The highest prevalence of Blastocystis sp. was found in sheep (38.2%) among the farm animals. The SSU rRNA sequence analysis revealed two animal-specific subtypes, including ST10 in cattle and sheep and ST14 in water buffaloes. The zoonotic subtype ST7 was identified in chickens. Our results indicated a high prevalence of animal-specific subtypes in livestock and zoonotic subtype ST7 in chickens, highlighting the potential risk of chickens for zoonotic transmission of Blastocystis in the research area. This study is the first large-scale evaluation of Blastocystis in animal hosts in Turkey, and contributes to the molecular epidemiology and genetics of Blastocystis. Our results should be considered by authorities as an indication of the zoonotic importance of Blastocystis sp. and the need for surveillance in public health intervention programs.

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.

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.

Waterborne protozoan pathogens in environmental aquatic biofilms: Implications for water quality assessment strategies

Biofilms containing pathogenic organisms from the water supply are a potential source of protozoan parasite outbreaks and a significant public health concern. The aim of the present study was to demonstrate the simultaneous and multi-spatial occurrence of waterborne protozoan pathogens (WBPP) in substrate-associated biofilms (SAB) and compare it to surface water (SW) and sediments with bottom water (BW) counterparts using manual filtration and elution from low-volume samples. For scenario purposes, simulated environmental biofilm contamination was created from in-situ grown one-month-old SAB (OM-SAB) that were spiked with Cryptosporidium parvum oocysts. Samples were collected from the largest freshwater reservoirs in Luzon, Philippines and a University Lake in Thailand. A total of 69 samples (23 SAB, 23 SW, and 23 BW) were evaluated using traditional staining techniques for Cryptosporidium, and Immunofluorescence staining for the simultaneous detection of Cryptosporidium and Giardia. WBPP were found in 43% SAB, 39% SW, and 39% BW of the samples tested in the present study with SAB results reflecting SW and BW results. Further highlights were demonstrated in the potential of using low-volume samples for the detection of parasites in source water. Scanning electron microscopy of OM-SAB samples revealed a naturally-associated testate amoeba shell, while Cryptosporidium oocysts spiked samples provided a visual profile of what can be expected from naturally contaminated biofilms. This study provides the first evidence for the simultaneous and multi-spatial occurrence of waterborne protozoan pathogens in low-volume aquatic matrices and further warrants SAB testing along with SW and BW matrices for improved water quality assessment strategies (iWQAS).

Molecular analysis of Blastocystis sp. and its subtypes from treated wastewater routinely used for irrigation of vegetable farmlands in Iran

Treated wastewater samples were collected, filtered using sterile 47-mm cellulose nitrate membrane and DNA extracted from the filtered materials. The presence of Blastocystis sp. was confirmed via polymerase chain reaction (PCR) targeting the SSU rRNA gene of Blastocystis sp. in 5/12 of samples. Based on the subtype analysis after sequencing, 2, 2 and 1 of ST2, ST6 and ST8 were detected among the isolates, respectively. Furthermore, both ST6s were allele 139, alleles 11 and 138 were identified in ST2 and the only ST8 was allele 95. The phylogenetic tree showed that one of ST2 was clustered together with those ST2 that were already reported from humans and animals. The presence of Blastocystis sp. in treated wastewater can indicate the potential role of this type of water for irrigation in the transmission of pathogenic microorganisms to downstream farmlands.

Blastocystis subtype 1 (allele 4); Predominant subtype among tuberculosis patients in Iran

BACKGROUND

Blastocystis and tuberculosis are two public health issues that are frequently reported in regions with low level of hygiene. Therefore, the current study aimed to investigate Blastocystis subtype and allele distribution in TB patients.

METHODS

Totally, 161 stool samples were taken from TB patients who were undergoing anti-MTB treatment. Stool samples were concentrated using conventional formalin-ether technique and examined using Lugol's iodine staining under light microscopy. DNA extraction was carried out and discriminative fragment was amplified and sequenced. With comparison in GenBank database, relevant subtypes and alleles were characterized and phylogenetically analyzed using MEGA v.7 and Tamura 3-parameter model.

RESULTS

In total, from 161 stool samples, 19 samples were suspected to be Blastocystis-positive. The expected fragment was amplified in 13 (8.07%) of samples. Accordingly, 11/13 (84.62%) of Blastocystis cases settled in urban and 2/13 (15.38%) were villagers. Close-contact with animals was also seen among 7/13 (53.84%) of samples. Subtype 1 (7/13; 53.84%) was the most prevalent followed by subtype 2 (5/13; 38.46%) and subtype 3 (1/13, 7.69%). All ST1 were allele 4, while alleles 9, 11 and 12 were seen in ST2 and allele 34 was the only allele observed in ST3. All three subtypes were clearly separated, while there was no separation between sequences from TB and non-TB patients.

CONCLUSION

Blastocystis ST1 was the most prevalent subtype in TB patients and there was no difference between Blastocystis isolates from TB and non-TB human subjects.

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.