Blastocystis subtypes in symptomatic and asymptomatic family members and pets and response to therapy

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

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

Detection and Molecular Characterization of Blastocystis Species in Polish Soldiers Stationed in the Republic of Kosovo

Blastocystis species (sp.) is one of the less well-understood water- and foodborne protozoa of medical and veterinary importance linked to different gastrointestinal disorders. Soldiers participating in military missions are particularly vulnerable to infection with this protozoa. The present study used molecular methods to detect, identify, and subtype (ST) Blastocystis sp. in Polish soldiers stationed in the Republic of Kosovo. Fecal samples were collected from 192 soldiers on arrival and after four months of stay. After DNA extraction, the barcoding region of the small subunit ribosomal RNA (SSU-rRNA) gene was amplified and sequenced. The DNA of Blastocystis sp. was detected in six (3.13%) and thirty (15.16%) samples in the first and second batch, respectively. Sequencing analysis revealed infections with ST 2, 3, 4, and 7. There was no statistical association between Blastocystis sp. infection and the parasite's ST or the age or rank of soldiers. The results indicate that the visit to a new environment and prolonged stay in the area of military operation in Kosovo resulted in a significant increase in both Blastocystis sp. infections and ST diversity among surveyed soldiers. This shows the need to undertake appropriate countermeasures to reduce Blastocystis infections in the military environment abroad.

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.

Exploring Blastocystis genetic diversity in rural schoolchildren from Colombia using next-generation amplicon sequencing reveals significant associations between contact with animals and infection risk

Blastocystis is a common intestinal protist with a global distribution in humans and many other animals. Yet, the status of Blastocystis as a pathogen, the risk factors associated with its transmission, and its zoonotic potential remain ill-defined. Here, we explored subtype (ST) diversity and potential risk factors for Blastocystis infection in 98 children from Apulo, Colombia. Samples were screened for Blastocystis via PCR, and ST identification was performed through next-generation amplicon sequencing (NGS). Associations between the presence of Blastocystis and individual STs and sociodemographic variables were assessed via logistic regression analyses. Seventy-one samples (72.4%) were Blastocystis-positive, and NGS revealed the presence of five STs (ST1-ST5). ST1, ST2, and ST3 were common and observed in nearly equal proportions (~ 40%), while samples with ST4 (1.4%) and ST5 (5.6%) were comparatively rare. The presence of mixed STs in the same sample was also common (28.2%). Comparisons among children within the same household identified that shared ST profiles were common, but diversity within family units was also observed. Logistic regression analyses returned significant associations between the presence of Blastocystis, individual subtypes, or mixed subtypes for several variables. Intriguingly, the presence of animals was one of the most common significant associations. Taken together, these data represent an important step forward in understanding both the potential routes and risk factors that may influence Blastocystis transmission and will be useful in shaping future studies which seek to clarify the relationships between STs, pathogenicity, and zoonotic transmission.

Molecular identification of Cryptosporidium, Giardia, and Blastocystis from stray and household cats and cat owners in Tehran, Iran

Cryptosporidiosis, giardiasis, and blastocystosis are among the most important parasitic diseases common between humans and cats. In addition, there are concerns about the possible transmission of zoonotic parasites from infected cats to humans. Hence, we investigated the molecular epidemiology of Cryptosporidium spp., Giardia duodenalis, and Blastocystis sp. in stray and household cats and cat owners. Our study was performed on 132, 33, and 33 fecal samples of stray and household cats, as well as cat owners in Tehran, Iran. Cryptosporidium spp. was identified using a nested PCR targeting the small subunit ribosomal RNA gene (SSU rRNA) and sequencing the internal amplified fragments. Furthermore, to perform multilocus genotyping of G. duodenalis, the ß-giardin (bg), glutamate dehydrogenase (gdh), and triosephosphate isomerase (tpi) genes were amplified to assess the DNA of G. duodenalis in the fecal samples of cats and cat owners. In addition, Blastocystis was detected by targeting the SSU rRNA gene, and the subtypes of Blastocystis were determined via the sequencing of amplicons. Cryptosporidium felis and Cryptosporidium canis were detected in seven stray cats (5.3%) and one household cat (3%). The bg gene of G. duodenalis was amplified and successfully sequenced in two (1.5%) stray cats and revealed assemblages F and B of G. duodenalis. Sequencing and phylogenic analysis of SSU rRNA gene nucleotide sequences of Blastocystis detected ST5 and ST10 in stray cats (1.5%), ST1 in household cats (9.1%), and ST1, ST2, ST3, and ST7 in owners (30.3%). The low prevalence of Cryptosporidium, Giardia and Blastocystis in cats and the presence of species/assemblages/subtypes with limited zoonotic potential indicate that cats had a minor role in their owners' infection in the investigated population. However, the presence of zoonotic protozoa in cats suggests the necessity of special attention to high-risk individuals during close contact with cats. Therefore, it is recommended that veterinarians, physicians, and urban managers plan to prevent, control, or treat these parasites to help the urban community live healthily alongside cats.

Resistance of Blastocystis to chlorine and hydrogen peroxide

Blastocystis is a ubiquitous, widely distributed protist inhabiting the gastrointestinal tract of humans and other animals. The organism is genetically diverse, and so far, at least 28 subtypes (STs) have been identified with ST1-ST9 being the most common in humans. The pathogenicity of Blastocystis is controversial. Several routes of transmission have been proposed including fecal-oral (e.g., zoonotic, anthroponotic) and waterborne. Research on the latter has gained traction in the last few years with the organism having been identified in various bodies of water, tap water, and rainwater collection containers including water that has been previously filtered and/or chlorinated. Herein, we assessed the resistance of 11 strains maintained in culture, spanning ST1-ST9 to various chlorine and hydrogen peroxide concentrations for 24 h, and performed recovery assays along with re-exposure. Following the treatment with both compounds, all subtypes showed increased resistance, and viability could be visualized at the cellular level. These results are hinting at the presence of mechanism of resistance to both chlorine and hydrogen peroxide. As such, this pilot study can be the platform for developing guidelines for water treatment processes.

First Report of Blastocystis spp. Infection in Pet Birds in Henan Province, Central China

Blastocystis spp. are common intestinal parasites found in humans and many kinds of animals. Blastocystis spp. infection is associated with a variety of symptoms, including diarrhea, abdominal pain, and chronic urticaria, among which asymptomatic infection is the most common. Among the 11 potentially zoonotic subtypes of Blastocystis spp., 9 subtypes have been reported in bird species. The purpose of this study was to detect the infection rate and gene subtype distribution of Blastocystis spp. in pet birds in Henan Province, Central China, to provide a foundation for preventing and controlling Blastocystis spp. in pet birds. Fecal DNA was extracted from 382 fresh fecal samples of pet birds collected from five areas in Henan Province, Central China. Twenty-three species of pet birds from four orders, from local pet trading markets, parks, and individuals, were sampled. All DNA samples were investigated by PCR, and positive samples were sequenced to analyze the gene subtypes based on the small ribosomal subunit (SSU rRNA) gene. Blastocystis spp. was detected in 0.8% of the samples. Further DNA sequencing and phylogenetic analyses resulted in the identification of two known zoonotic subtypes, ST1 (n = 2) and ST7 (n = 1). As far as we know, this is the first time that ST1 subtype has been reported in Chinese birds. It is found that pet birds may be the hosts of zoonotic Blastocystis spp. subtypes, and the role of birds in transmitting Blastocystis spp. to humans needs to be further studied.

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.

Prevalence and molecular subtyping of Blastocystis in domestic pigeons in Henan Province, Central China

Blastocystis is an anaerobic intestinal protozoan parasite found in humans and many kinds of animals that mainly causes diarrhea, abdominal pain and other clinical symptoms. At present, research on the prevalence and subtype diversity of Blastocystis in domestic pigeons is very limited. The purpose of this study was to detect the infection rate and gene subtype distribution of Blastocystis in domestic pigeons in Henan Province, Central China, to provide a foundation for preventing and controlling Blastocystis in domestic pigeons. Fecal DNA was extracted from 504 fresh fecal samples of pigeons collected from 4 areas in Henan Province, Central China. All DNA samples were investigated by polymerase chain reaction (PCR), and positive samples were sequenced to analyze the gene subtypes based on small ribosomal subunit (SSU rRNA) gene. The overall infection rate of Blastocystis in pigeons in Henan Province was 7.7% (39/504). Four subtypes (STs) of Blastocystis were identified including ST1 (2/39, 5.1%), ST3 (16/39, 41.0%), ST4 (1/39, 2.6%) and ST7 (20/39, 51.3%), all of which belonged to zoonotic subtypes, and ST7 was the dominant gene subtype. The results show that Blastocystis infection is common in domestic pigeons in Henan Province, Central China, and the pathogen were zoonotic subtypes. Particular attention should be given to reducing the risk of transmission of Blastocystis from domestic pigeons to humans.

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.

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

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

Epidemiology and subtype distribution of Blastocystis in humans: A review

Blastocystis is a commonly encountered gastrointestinal protozoan in humans and animals with uncertain pathogenicity. Despite its potential public health impact, epidemiological data regarding the prevalence and molecular subtype (ST) distribution of Blastocystis have been rarely reported. Among Blastocystis STs, ST1-ST4 are common in humans, including healthy and immunodeficient populations. According to the Chi-squared (χ²) association based on the data compiled for this cross-sectional study, the presence of ST1 is associated with asymptomatic infection, whereas the presence of ST4 is associated with symptomatic infection. However, cross-sectional studies cannot clarify the potential pathogenicity of Blastocystis, unlike in vivo and in vitro studies. Poor hygiene, poor sanitation and zoonotic transmission are possible factors associated with high Blastocystis prevalence, although this protozoan may be part of the normal healthy human gastrointestinal microbiota. This review covers the prevalence, STs and distribution of Blastocystis infection in humans. Thus, future epidemiological and subtyping studies could reveal new STs in humans as well as possible associations of STs with disease, drug resistance and related mechanisms such as protease activity. These associations with proper ST identification may facilitate the control of potential threats to host health, including the direct pathogenic effects of Blastocystis or alterations of the gastrointestinal microbiome.

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

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

Molecular identification and subtyping of Blastocystis sp. in hospital patients in Central China

Blastocystis is a common enteric protist that inhabits the gastrointestinal tract of approximately 1 billion people worldwide. In this study, a total of 1,070 patients from two hospitals in Zhengzhou, Central China were enrolled to know molecular characteristics of Blastocystis sp. The microorganism was identified and subtyped with a PCR amplification and sequencing of the small subunit ribosomal deoxyribonucleic acid (SSU-rDNA). The overall minimum prevalence of Blastocystis sp. in participants was 3.1% (33/1070). Although there were no significant differences on Blastocystis sp. infections among study sites, age groups, and gender, the higher infection was observed in the patients with gastrointestinal diseases (8.8%, 15/170). Sequence analysis of the 33 isolates revealed three known subtypes, such as ST1 (n = 7), ST3 (n = 23), and ST7 (n = 3). Among them, ST3 was the dominant subtype being detected in 23 isolates (69.7%), followed by ST1 (21.2%, 7/33) and ST7 (9.1%, 3/33). The phylogenetic analysis demonstrated that three subtypes (ST1, ST3 and ST7) were clustered with their reference sequences with good bootstrap support. The subtype determination of Blastocystis sp. isolates by the phylogenetic analysis was well supported by online platform. The present study provides the first molecular report of Blastocystis sp. infections in hospital patients in Central China.

The Prevalence of Blastocystis Infection in Pediatric Patients with Malignancy: A Single-Center Study in Ahvaz, Iran

Background: Blastocystis spp. is known as one of the few intestinal parasites, prevalent in more than 5% and 30 - 60% of the population in industrialized and developing countries, respectively. In this respect, immunocompromised individuals, such as patients undergoing chemotherapy or those with malignancies, are at risk of the clinical symptoms of Blastocystis infection; however, the given condition is often self-limiting in healthy individuals. Objectives: The current study aimed at evaluating the prevalence of Blastocystis infection in children with malignancies receiving chemo drugs. Methods: The current descriptive, cross-sectional study was conducted on 52 stool specimens collected from patients with cancer admitted to the Oncology Ward of Shahid Baqaei 2 Hospital, Ahvaz, Iran, for six months. A standardized questionnaire was filled out for all cases. Each specimen was also prepared using direct smear, the Lugol iodine staining, and the formalin-ether condensation method. Results: Blastocystis spp. was detected in 21.1% of the cases among them, 11.5% demonstrated gastrointestinal symptoms; therefore, a significant relationship was observed between Blastocystis infection and gastrointestinal symptoms. Conclusion: Patients undergoing chemotherapy should be screened for opportunistic parasitic infections such as Blastocystis to avoid potentially life-threatening outcomes. Besides, further studies are required to identify the subtypes of Blastocystis.

Genetic Analysis of Zoonotic Gastrointestinal Protozoa and Microsporidia in Shelter Cats in South Korea

Feral cats that are roaming outside can serve as reservoirs for zoonotic pathogens, negatively impacting public health. They may experience high levels of parasitic infection. Some gastrointestinal protozoa and microsporidia possessing zoonotic potential in cats include Cryptosporidium spp., Giardia duodenalis, Blastocystis sp., Enterocytozoon bieneusi, and Toxoplasma gondii. Here, we show the infection rates and risk factors of intestinal protozoa and microsporidia detected from shelter cats on Jeju Island in South Korea in 2020. Among 158 cats, we detected genes for five internal protozoa and microsporidia, namely, Cryptosporidium felis (0.6%), G. duodenalis (3.8%), Blastocystis sp. (0.6%), E. bieneusi (3.8%), and T. gondii (1.3%). Furthermore, 16 cats (10.1%) were PCR-positive for at least one protozoan or microsporidium. To our knowledge, this study is the first to describe the existence of C. felis, G. duodenalis assemblage F, Blastocystis sp. ST4 subtype, and E. bieneusi genotype Peru11 in cats in South Korea. Despite the small number of positive samples, this study expands our understanding of the incidence of zoonotic gastrointestinal protozoa and microsporidia in shelter cats and genetically characterizes the isolates found in the infected animals. Moreover, these findings emphasize the need for a better control strategy on protozoa and microsporidia in cats, tailored to their individual needs, to protect animal and public health.

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.

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.

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.

Two-day enema antibiotic therapy for parasite eradication and resolution of symptoms

BACKGROUND

Blastocystis hominis (B. hominis) and Dientamoeba fragilis (D. fragilis) are two protozoan parasites of human bowel that are found throughout the world. There is still debate about the pathogenicity of these protozoans, despite them being commonly associated with gastrointestinal symptoms and can cause health issue in both children and adults. These parasites are usually transmitted through faecal-oral contact particularly under poor hygiene conditions or food/water contamination. Once a person is infected, the parasites live in the large intestine and are passed in the faeces.

AIM

To investigate the effect of triple antibiotic therapy using enema infusion in the treatment of B. hominis and D. fragilis infections.

METHODS

This retrospective longitudinal study was conducted in a single medical centre, which included fifty-four patients (≥ 18 years) who were positive for D. fragilis, B. hominis or both between 2017 and 2018. The treatment consisted of triple antibiotics that were infused over two consecutive days through rectal enema. Faecal samples were collected from participants pre- and post-treatment and were tested for parasites using microscopy and polymerase chain reaction. Patients’ symptoms were recorded prior and after the treatment as well as patient demographic data.

RESULTS

Patients (n = 54), were either positive for B. hominis (37%), D. fragilis (35%) or both (28%). All patients completed the two-day treatment and no serious adverse effect was reported. The most common side effect experienced by the patients during the treatment was urine discolouration which was cleared by six weeks of follow-up. Common symptoms reported prior to treatment were diarrhoea, abdominal pain, constipation and fatigue. Other symptoms included abdominal discomfort, dizziness and blood in the stool. Eighty-nine percent of patients completed a final stool test post-treatment. At six weeks post-treatment, 79% of patients cleared the parasites from their faeces. Symptoms such as abdominal discomfort, dizziness and blood in the stool decreased significantly at both seven days and six weeks post-treatment (P < 0.040). The enema retention time, bowel preparation, previous antibiotic treatment or previous gastrointestinal problems had no significant effect on parasite eradication.

CONCLUSION

Overall, eradication of parasites and improvement of clinical outcomes were observed in treated patients, showing the efficacy of this combination to eradicate the parasites and provide positive clinical outcome.

Blastocystis sp. Subtype Diversity in Wild Carnivore Species from Spain

The occurrence and molecular diversity of the stramenopile eukaryote Blastocystis sp. was investigated by PCR and sequencing (Sanger and NGS) methods in 380 faecal specimens of free-living carnivores in Spain. Blastocystis sp. was confirmed in 1.6% (6/380) of the specimens analysed. Two samples from a common genet and a fox were successfully subtyped as ST7 by Sanger. Using NGS, ST14 was found in a fox and a European polecat, ST7 in a fox, and two additional foxes presented mixed infections of ST1/ST2/ST4 and ST1/ST2/ST7, respectively. Wild carnivore species could act as carriers of zoonotic Blastocystis subtypes.

Molecular characterization of Blastocystis subtypes in HIV-positive patients and evaluation of risk factors for colonization

Background

Blastocystis is one of the most common intestinal protozoa in human faecal samples with uncertain impact on public health. Studies on the prevalence of Blastocystis in HIV-positive patients are limited and dated.

Methods

A cross-sectional study was carried out involving 156 HIV-positive patients to evaluate the prevalence of Blastocystis-subtypes by molecular amplification and sequencing the small subunit rRNA gene (SSU rDNA), to identify the risk factors for its transmission, to examine the relationship between the presence of the protist and gastrointestinal disorders. Furthermore, the evaluation of the faecal calprotectin by immunoassay from a sample of subjects was performed to evaluate the gut inflammation in Blastocystis-carriers.

Results

Blastocystis-subtypes ST1, ST2, ST3, ST4 were identified in 39 HIV-positive patients (25%). No correlation was found between the presence of the protist and virological or epidemiological risk factors. Blastocystis was more frequently detected in homosexual subjects (p = 0.037) infected by other enteric protozoa (p = 0.0001) and with flatulence (p = 0.024). No significant differences in calprotectin level was found between Blastocystis-carriers and free ones.

Conclusions

Blastocystis is quite common in HIV-positive patients on ART showing in examined patients 25% prevalence. Homosexual behaviour may represent a risk factor for its transmission, while CD4 count and viremia didn’t correlate with the presence of the protist. The pathogenetic role of Blastocystis remains unclear and no gut inflammation status was detected in Blastocystis-carriers. The only symptom associated with Blastocystis was the flatulence, evidencing a link between the presence of the protist and the composition and stability of gut microbiota.

Molecular epidemiology of Blastocystis sp. in dogs housed in Italian rescue shelters

Blastocystis is a ubiquitous protozoan with a wide range of hosts. In humans, its presence has been associated with gastrointestinal disorders, although its role as a pathogen still needs to be elucidated. Until now, 17 Blastocystis subtypes (STs) have been identified, with ST1-ST4 the most commonly found in humans. Among domestic animals, the same STs reported in humans have been detected in dogs. An epidemiological survey on dog kennels was carried out to evaluate the prevalence of Blastocystis and the STs involved. Overall, 99 faecal samples were collected from the rescue shelters. Blastocystis detection was performed through conventional barcoding PCR targeting the 1800-bp SSU-rDNA, followed by sequencing and phylogenetic analysis. Blastocystis DNA was found in 21 faecal samples (21.2%), and all samples were successfully sequenced and identified as ST3 in a unique monophyletic group. The presence of Blastocystis was reported for the first time in dogs from Italy, with the identification of ST3, the subtype most commonly found in humans.

Epidemiology of Blastocystis sp. infection in China: a systematic review

Blastocystis sp., a unicellular intestinal parasite in humans and animals worldwide, is frequently found in immunocompromized patients and people in close contact with animals. Here, we reviewed recent studies on the prevalence, subtypes, and distribution of Blastocystis infection in humans and animals in China. To date, more than 12 provinces have reported Blastocystis infection in humans, with identification of six different subtypes (ST1, ST2, ST3, ST4, ST5, and ST6). The overall infection rate reported was 3.37% (3625/107,695), with the lowest prevalence (0.80%) in Fujian province and the highest prevalence (100%) in Guangdong province. ST3 (62%, 186/300) was the most dominant subtype, identified in all tested provinces in China. A total of eight provinces have reported Blastocystis infection in various animals, with the overall prevalence being 24.66% (1202/4874). Molecular analysis revealed 14 subtypes that infected animals, including 10 known (ST1, ST2, ST3, ST4, ST5, ST6, ST7, ST10, ST13, ST14), and 4 novel (Novel1, Novel2, Novel3, Novel4) subtypes. ST5 was the dominant subtype infecting artiodactyls (44.1%, 460/1044), while ST1 commonly infected carnivores (45.5%, 5/11). These findings provide insights into the epidemiological behavior of Blastocystis sp. in China, and could help in developing effective control strategies against the parasite.

Surface ultrastructure, protein profile and zymography of Blastocystis species isolated from patients with colorectal carcinoma

Oncogenic potential of Blastocystis species have been predicted on reporting the enhanced proliferation of human colorectal cancer cells by the parasite solubilized antigen in vitro, and the enhanced drug-induced carcinogenesis by infection in vivo. The present study is the first to investigate some phenotypic characters, namely the surface ultrastructure, protein profiles and protease activity of Blastocystis sp. isolated from three different clinical groups: colorectal carcinoma (CRC) patients, symptomatic and asymptomatic infected persons. Under SEM, all CRC Blastocystis sp. isolates had a very rough intensely folded surface in comparison to the less rough and completely smooth surface of all symptomatic and asymptomatic Blastocystis sp. Non-CRC isolates, respectively. Under reducing conditions, the sodium dodecyl sulfate-polyacrylamide gel electrophoresis had shown a significant presence of 2 protein bands of 230 and 32 KDa in 42.9% of Blastocystis sp. CRC isolates with their complete absence from Non-CRC isolates. While using non-reducing condition with the incorporation of gelatin in the gel to study the protease activity of the parasite, no significant difference existed between isolates of the three groups. In conclusion, the significant difference in surface ultrastructure and in protein profiles exists between Blastocystis sp. of CRC and Non-CRC isolates. These differences might be either secondary to the altered gut environment in the presence of CRC or are indicators of a different pathogenic potential of the parasite isolates inducing malignancy.

Prevalence of Cryptosporidium, Giardia, Blastocystis, and trichomonads in domestic cats in East China

The cat is a reported reservoir for several zoonotic pathogens, including Cryptosporidium spp., Giardia duodenalis, and Blastocystis sp. These parasites represent a significant, but often neglected, threat to humans and animals. Furthermore, Tritrichomonas foetus has been described inhabiting the digestive tract of cats, and may be causative agents of gastrointestinal symptoms. However, scant data are available concerning the molecular epidemiology of these parasites in domestic cats in China. This study examined fecal samples from domestic cats in Eastern China to unravel the molecular epidemiology of four protozoans. Of the 346 samples examined, 47 (13.6%) were positive for the detected pathogens, including 8 (2.3%), 5 (1.4%), 2 (0.6%), and 35 (10.1%) samples positive for Cryptosporidium spp., G. duodenalis, Blastocystis sp., and T. foetus, respectively. Co-infection with Cryptosporidium spp. and T. foetus was detected in three cats, no other mixed infections were observed. No age, sex or fecal condition predisposition was observed with any of the four pathogens. The species/assemblages/subtypes/genotypes were C. felis, Assemblage A and F, ST1, and cat genotype for Cryptosporidium spp., G. duodenalis, Blastocystis sp., and T. foetus detected in this study, respectively. The presence of zoonotic species/assemblages/subtypes/genotypes poses a threat to public health. These findings provide useful information for the design of prevention and control strategies to reduce the burden of protozoal infections in cats.

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.

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.

Distribution of Blastocystis subtypes isolated from humans from an urban community in Rio de Janeiro, Brazil

Background

Blastocystis is a cosmopolitan protist parasite found in the human gastrointestinal tract and is highly prevalent in developing countries. Recent molecular studies have revealed extensive genetic diversity, which has been classified into different subtypes (STs) based on sequence analysis of small subunit ribosomal RNA gene. Blastocystis is one of the most common fecal parasites in Brazil, but the diversity of subtypes remains unknown in the country. This study aimed to determine the distribution of Blastocystis STs in an urban community in Duque de Caxias, Rio de Janeiro, Brazil.

Methods

A total of 64 stool samples positive for Blastocystis in Pavlova’s medium were subtyped by PCR and sequenced using primers targeting the small subunit rRNA gene, in addition to phylogenetic analysis and subtype-specific PCR using sequence-tagged-site (STS) primers.

Results

Endolimax nana (14%), Entamoeba complex (10.5%), Taenia sp. (0.6%), Trichuris trichiura (1.3%) and Enterobius vermicularis (1.3%) were detected in Blastocystis-positive samples. Of the 64 samples tested by PCR/DNA sequencing, 55 were identified as ST1 (42%), ST3 (49%), ST2 (7%) and ST4 (2%), and the presence of mixed ST (ST1 + ST3) infection was detected in nine samples (14%).

Conclusions

DNA sequencing and phylogenetic analysis of Brazilian Blastocystis isolates identified four different subtypes. To our knowledge, this study provided the first genetic characterization of Blastocystis subtypes in an urban area of Rio de Janeiro, Brazil. We also identified ST4 for the first time in Brazil. Further studies are necessary to determine the distribution of STs across human populations in Rio de Janeiro.

Blastocystis subtyping and its association with intestinal parasites in children from different geographical regions of Colombia

Blastocystis is a common enteric protist colonizing probably more than 1 billion people with a large variety of non-human hosts. Remarkable genetic diversity has been observed, leading to the subdivision of the genus into multiple subtypes (ST), some of which are exclusively found in non-human hosts. The aim of this study was to determine the distribution of Blastocystis STs/18S alleles in symptomatic (abdominal pain, anal pruritus, diarrhea, headache, nauseas and/or vomit) and asymptomatic children from nine geographical regions of Colombia. A total of 2026 fecal samples were collected as part of a national survey to estimate the frequency of intestinal parasites in children. A set of 256 samples that were Blastocystis positive was finally selected. The samples were submitted to DNA extraction, Real Time PCR and sequencing using Blastocystis-specific primers targeting the small subunit rRNA gene for ST identification. DNA of Ascaris lumbricoides (16.4%), Trichuris trichiura (8.2%), hookworms (Necator americanus/Ancylostoma duodenale) (7.3%), Giardia duodenalis (23.1%), Entamoeba complex (82%), Entamoeba coli (55%), Hymenolepis nana (0.8%), Endolimax nana (33.2%) and Neobalantidium coli (2.7%) was detected in the Blastocystis-positive samples. We detected ST1 (21.4%), ST2 (19.5%), ST3 (55.5%), ST4 (0.8%), ST6 (2%) and ST7 (0.8%); alleles 1, 2, 4, 81, 82 and 83 for ST1; alleles 9, 11, 12, 15, 67, 71 and 73 for ST2; alleles 34, 36, 38, 45, 49, 55, 134 and 128 for ST3; allele 42 for ST4; allele 122 for ST6, and allele 142 for ST7. Further studies implementing high-resolution molecular markers are necessary to understand the dynamics of Blastocystis transmission and the role of this Stramenopila in health and disease.

Molecular Epidemiology of Blastocystis sp. in Various Animal Groups from Two French Zoos and Evaluation of Potential Zoonotic Risk

Blastocystis sp. is a common intestinal parasite infecting humans and a wide range of animals worldwide. It exhibits an extensive genetic diversity and 17 subtypes (STs) have thus far been identified in mammalian and avian hosts. Since several STs are common to humans and animals, it was proposed that a proportion of human infections may result from zoonotic transmission. However, the contribution of each animal source to human infection remains to be clarified. Therefore, the aim of this study was to expand our knowledge of the epidemiology and host specificity of this parasite by performing the largest epidemiological survey ever conducted in animal groups in terms of numbers of species screened. A total of 307 stool samples from 161 mammalian and non-mammalian species in two French zoos were screened by real-time PCR for the presence of Blastocystis sp. Overall, 32.2% of the animal samples and 37.9% of the species tested were shown to be infected with the parasite. A total of 111 animal Blastocystis sp. isolates were subtyped, and 11 of the 17 mammalian and avian STs as well as additional STs previously identified in reptiles and insects were found with a varying prevalence according to animal groups. These data were combined with those obtained from previous surveys to evaluate the potential risk of zoonotic transmission of Blastocystis sp. through the comparison of ST distribution between human and animal hosts. This suggests that non-human primates, artiodactyls and birds may serve as reservoirs for human infection, especially in animal handlers. In contrast, other mammals such as carnivores, and non-mammalian groups including reptiles and insects, do not seem to represent significant sources of Blastocystis sp. infection in humans. In further studies, more intensive sampling and screening of potential new animal hosts will reinforce these statements and expand our understanding of the circulation of Blastocystis sp. in animal and human populations.

Prevalence and genetic diversity of Blastocystis in family units living in the United States

The human gut is host to a diversity of microorganisms including the single-celled microbial eukaryote Blastocystis. Although Blastocystis has a global distribution, there is dearth of information relating to its prevalence and diversity in many human populations. The mode of Blastocystis transmission to humans is also insufficiently characterised, however, it is speculated to vary between different populations. Here we investigated the incidence and genetic diversity of Blastocystis in a US population and also the possibility of Blastocystis human-human transmission between healthy individuals using family units (N=50) living in Boulder, Colorado as our sample-set. Ten of the 139 (~7%) individuals in our dataset were positive for Blastocystis, nine of whom were adults and one individual belonging to the children/adolescents group. All positive cases were present in different family units. A number of different Blastocystis subtypes (species) were detected with no evidence of mixed infections. The prevalence of Blastocystis in this subset of the US population is comparatively low relative to other industrialised populations investigated to date; however, subtype diversity was largely consistent with that previously reported in studies of European populations. The distribution of Blastocystis within family units indicates that human-human transmission is unlikely to have occurred within families that participated in this study. It is not unexpected that given the world-wide variation in human living conditions and lifestyles between different populations, both the prevalence of Blastocystis and its mode of transmission to humans may vary considerably.

Blastocystis in ulcerative colitis patients: Genetic diversity and analysis of laboratory findings

OBJECTIVE

To determine Blastocystis frequency and subtypes (ST) in ulcerative colitis (UC) patients and analyse some laboratory findings between Blastocystis positive and negative cases.

METHODS

Faecal samples from 150 UC patients in Adnan Menderes University, Training and Research Hospital were examined by direct microscopy and cultivated in Jones medium. Blastocystis positive cultures were subjected to DNA isolation and subtypes were identified by sequencing of barcode region. A retrospective analysis was conducted on C reactive protein (CRP), leucocyte counts (WBC), neutrophil counts, and sedimentation rates.

RESULTS

The overall positive rate of Blastocystis was 8% (12 patients) and the most abundant subtype was ST3 (eight isolates, 66.7%), followed by ST1, ST2 and ST7. Laboratory findings between Blastocystis infected and non-infected UC patients were not significantly different. Blastocystis frequency was 3.8% among the patients in active stage, while it was 11.8% among the patients in remission stage.

CONCLUSIONS

The present study confirms previous findings that have indicated the predominance of Blastocystis ST3 in humans and contributes additional evidence that suggests the low colonisation of Blastocystis infection in ulcerative colitis patients during active stage.

HIGH PREVALENCE OF Blastocystis spp. INFECTION IN CHILDREN AND STAFF MEMBERS ATTENDING PUBLIC URBAN SCHOOLS IN SÃO PAULO STATE, BRAZIL

After a gastroenteritis outbreak of unknown etiology in the municipality of Sebastião da Grama, SãoPaulo, Brazil, we conducted a parasitological survey to establish the epidemiological profile of enteroparasitosis in children and staff members attending the public urban schools in operation in town. The cross-sectional study evaluated 172 children aged 11 months to 6 years old and 33 staff members aged 19 to 58 years old. Overall, 96 (55.81%) children and 20 (60.61%) staff members were mono-parasitized, while 58 (33.72%) children and 4 (12.12%) workers were poly-parasitized. Protozoa (88.37%; 72.73%) was more prevalent than helminthes (3.48%; 0%) in children and staff members respectively.Blastocystis spp. was the most prevalent parasite in children (86.63%) and staff members (66.67%). The age of 1 year old or less was found to be associated with increased prevalence of giardiasis [OR = 13.04; 95%CI 2.89-58.91; p = 0.00] and public garbage collection was identified as a protective factor against intestinal helminth infections [OR = 0.06; 95%CI 0.00-0.79; p = 0.03]. Although most of the children tested positive for Blastocystis spp. and also presented clinical signs/symptoms (62.2%), this association was not statistically significant [OR = 1.35; 95%CI 0.53-3.44; p = 0.51]. Intestinal parasites still represent a public health concern and this study underscores the importance of further investigations to better understand the pathogenic role of Blastocystis spp.

Geographic distribution of human Blastocystis subtypes in South America

Blastocystis is a cosmopolitan enteric protist colonizing probably more than 1 billion people. This protozoan exhibits genetic diversity and is subdivided into subtypes (STs). The aim of this study was to determine the distribution of Blastocystis STs in symptomatic and asymptomatic human samples from different countries of South America. A total of 346 fecal samples were genotyped by SSU rDNA showing ST1 (28.3%), ST2 (22.2%), ST3 (36.7%), ST4 (2%), ST5 (2.3%), ST6 (2%), ST7 (2.3%), ST8 (0.6%), ST12 (0.9%) and a novel ST (2.7%). These findings update the epidemiology of Blastocystis in South America and expand our knowledge of the phylogeographic differences exhibited by this stramenopile.

In Vitro Antimicrobial Susceptibility Patterns of Blastocystis

Blastocystis is the most common human enteric protist with controversial clinical significance. Metronidazole is considered a first-line treatment for Blastocystis infection; however, there has been increasing evidence for the lack of efficacy of this treatment. Treatment failure has been reported in several clinical cases, and recent in vitro studies have suggested the occurrence of metronidazole-resistant strains. In this study, we tested 12 Blastocystis isolates from 4 common Blastocystis subtypes (ST1, ST3, ST4, and ST8) against 12 commonly used antimicrobials (metronidazole, paromomycin, ornidazole, albendazole, ivermectin, trimethoprim-sulfamethoxazole [TMP-SMX], furazolidone, nitazoxanide, secnidazole, fluconazole, nystatin, and itraconazole) at 10 different concentrations in vitro. It was found that each subtype showed little sensitivity to the commonly used metronidazole, paromomycin, and triple therapy (furazolidone, nitazoxanide, and secnidazole). This study highlights the efficacy of other potential drug treatments, including trimethoprim-sulfamethoxazole and ivermectin, and suggests that current treatment regimens be revised.

Prevalence of blastocystis in shelter-resident and client-owned companion animals in the US Pacific Northwest

Domestic dogs and cats are commonly infected with a variety of protozoan enteric parasites, including Blastocystis spp. In addition, there is growing interest in Blastocystis as a potential enteric pathogen, and the possible role of domestic and in-contact animals as reservoirs for human infection. Domestic animals in shelter environments are commonly recognized to be at higher risk for carriage of enteropathogens. The purpose of this study was to determine the frequency of infection of shelter-resident and client-owned domestic dogs and cats with Blastocystis spp in the Pacific Northwest region of the USA. Fecal samples were collected from 103 shelter-resident dogs, 105 shelter-resident cats, 51 client-owned dogs and 52 client-owned cats. Blastocystis were detected and subtypes assigned using a nested PCR based on small subunit ribosomal DNA sequences. Shelter-resident animals were significantly more likely to test positive for Blastocystis (P<0.05 for dogs, P = 0.009 for cats). Sequence analysis indicated that shelter-resident animals were carrying a variety of Blastocystis subtypes. No relationship was seen between Blastocystis carriage and the presence of gastrointestinal disease signs in either dogs or cats. These data suggest that, as previously reported for other enteric pathogens, shelter-resident companion animals are a higher risk for carriage of Blastocystis spp. The lack of relationship between Blastocystis carriage and intestinal disease in shelter-resident animals suggests that this organism is unlikely to be a major enteric pathogen in these species.

Blastocystis, an unrecognized parasite: an overview of pathogenesis and diagnosis

Blastocystis sp. is among the few enteric parasites with a prevalence that often exceeds 5% in the general population of industrialized countries and can reach 30-60% in developing countries. This parasite is frequently found in people who are immunocompromised (patients with human immunodeficiency virus/acquired immunodeficiency syndrome or cancer) and a higher risk of Blastocystis sp. infection has been found in people with close animal contact. Such prevalence in the human population and the zoonotic potential naturally raise questions about the impact of these parasites on public health and has increased interest in this area. Recent in vitro and in vivo studies have shed new light on the pathogenic power of this parasite, suggesting that Blastocystis sp. infection is associated with a variety of gastrointestinal disorders, may play a significant role in irritable bowel syndrome, and may be linked with cutaneous lesions (urticaria). Despite recent significant advances in the knowledge of the extensive genetic diversity of this species, the identification of extracellular proteases as virulence factors and the publication of one isolate genome, many aspects of the biology of Blastocystis sp. remain poorly investigated. In this review, we investigate several biological aspects of Blastocystis sp. (diversity and epidemiology, diagnosis tools and pathophysiology). These data pave the way for the following challenges concerning Blastocystis sp. research: deciphering key biological mechanisms and pathways of this parasite and clarification of its clinical impact in humans.

Clinical pilot study: efficacy of triple antibiotic therapy in Blastocystis positive irritable bowel syndrome patients

Background

Blastocystis species are common human enteric parasites. Carriage has been linked to Irritable Bowel Syndrome (IBS). Treatment of Blastocystis spp. with antimicrobials is problematic and insensitive diagnostic methods and re-infection complicate assessment of eradication. We investigated whether triple antibiotic therapy comprising diloxanide furoate, trimethoprim/sulfamethoxazole and secnidazole (TAB) given to diarrhoea-predominant IBS (D-IBS) patients positive for Blastocystis would achieve eradication.

Methods

In a longitudinal, prospective case study 10 D-IBS Blastocystis-positive patients took 14 days of diloxanide furoate 500 mg thrice daily, trimethoprim/sulfamethoxazole 160/80 mg twice daily and secnidazole 400 mg thrice daily. Faecal specimens were collected at baseline, day 15 and 4 weeks after completion of TAB. Specimens were analysed using faecal smear, culture and polymerase chain reaction (PCR) of the 16 SSU rRNA. Patients kept a concurrent clinical diary.

Results

Six (60%) patients cleared Blastocystis spp. after TAB, including three who had failed previous therapy. Subtypes detected were ST3 (60%), ST4 (40%), ST1 (20%) and ST7, 8 (10%); four patients had mixed ST infections. Serum immunoglobulin A (IgA) levels were low in 40% of patients. Higher rates of Blastocystis clearance were observed in patients symptomatic for less than a year (Mann–Whitney, p = 0.032, 95% confidence) with no associations found with age, previous antibiotic therapy, faecal parasite load, ST, IgA level or clinical improvement.

Conclusions

Clearance of Blastocystis spp. was achieved with TAB in 60% of D-IBS patients, an improvement over conventional monotherapy. Higher clearance rates are needed to facilitate investigation of the relevance of this parasite in clinically heterogenous IBS.