Molecular phylogenies of Blastocystis isolates from different hosts: implications for genetic diversity, identification of species, and zoonosis

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

INTRODUCTION

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Blastocystis in Swiss children: a practical approach

Blastocystis is a parasite with a worldwide distribution and a varying prevalence in different countries. The pleomorphic nature of the protozoon and the lack of understanding a possible pathogenesis have led to confusion regarding its clinical significance. The aim of the study was to shed light on clinical characteristics of pediatric patients in Swiss children with a positive stool sample for Blastocystis, in order to provide recommendations for a practical approach for the clinician to know whom, when, and how to test. This is a retrospective study of pediatric patients, whose stool has been tested positive for Blastocystis in the last 10 years in northern Switzerland. A total of 4047 stool samples, belonging to 1887 different patients, were analyzed; 240 stool samples (of 160 patients) were tested positive for Blastocystis. On average, 2.2 (CI 1.98-2.35) stool samples per patient were analyzed, of which 1.48 (CI 1.36-1.61) were positive for Blastocystis. In 63% abdominal pain was the leading symptom, while in 17.5% it was an accidental finding without symptoms. There was a high significance in correlation of abdominal pain and chronicity (p < 0.0001) but none in diarrhea (p = 0.082) nor nausea/vomiting or other symptoms and chronicity. Followed by Entamoeba coli (8%), 26.3% of the patients with Blastocystis had a co-infection with another parasite, mostly Endolimax nana (13%).Conclusion: Carriage of Blastocystis is common; therefore, only children/teenagers at risk for a symptomatic Blastocystis infection should be tested. There is a good correlation between Blastocystis and chronic abdominal pain. Children with abdominal symptoms persisting over 4 weeks should have two different stool samples analyzed. No screening after travels/immigration is recommended.What is Known:• Blastocystis has a worldwide distribution.• The clinical significance is unclear.What is New:• Based on retrospective data, we recommend to only test children/teenagers with chronic abdominal pain for Blastocystis.• Two different stool samples should be examined by microscopy; serological investigations are not warranted.

Prevalence and subtype distribution of Blastocystis sp. infecting children from a rural community in Panama

Blastocystis sp. is a commonly reported intestinal parasite with a worldwide distribution. Phylogenetic analyses describe at least 17 subtypes for this parasite, and nine of them have been found in humans. However, the prevalence and some epidemiological characteristics of this parasitic infection in rural communities are not well known. The objective of this cross-sectional study was to evaluate the prevalence, subtypes, and epidemiological factors related to Blastocystis sp. Infection in children from of a small rural community in the central area of Panama. For this, 66 fecal samples from children (1 to 12 years old), were initially analyzed for the presence of parasites by a formalin-ethyl acetate/concentration method. Molecular detection and identification of Blastocystis sp. subtypes were carried out by amplification and sequencing of a partial fragment of the small-subunit ribosomal RNA gene. Using data from a questionnaire, analyses of epidemiological conditions potentially associated with Blastocystis sp. transmission were also conducted. Microscopic diagnostics showed that 33.3% (22/66) of the analyzed samples presented entero-parasites. Among them, Blastocystis sp. was the most prevalent, with 21.2% (14/66), followed by the E. histolytica/dispar/moshkovskii complex 4.5% (3/66), Giardia lamblia 1.5% (1/66) and Strongyloides stercoralis 1.5% (1/66). PCR-based analyses detected a prevalence of Blastocystis sp. infection of 74.2% (49/66) in apparently healthy children. Phylogenetic analysis revealed two different subtypes of this parasite: ST1 with 42.2% (28/66) infected, and ST3 with 31.8% (21/66) infected. In addition, recent diarrhea was significantly associated with Blastocystis sp. infection. None of the other risk factors evaluated was statistically associated with infection. These results highlight the need to further investigate clinical, epidemiological, and genetic characteristics of Blastocystis sp. infections in this community.

First Report on the Prevalence and Subtype Distribution of Blastocystis sp. in Edible Marine Fish and Marine Mammals: A Large Scale-Study Conducted in Atlantic Northeast and on the Coasts of Northern France

Blastocystis is frequently identified in humans and animal hosts and exhibits a large genetic diversity with the identification of 17 subtypes (STs). Despite its zoonotic potential, its prevalence and ST distribution in edible marine fish and marine mammals remain unknown. A large-scale survey was thus conducted by screening 345 fish caught in Atlantic Northeast and 29 marine mammals stranded on the coasts of northern France for the presence of the parasite using real-time Polymerase Chain Reaction PCR. The prevalence of the parasite was about 3.5% in marine fish. These animals were mostly colonized by poikilotherm-derived isolates not identified in humans and corresponding to potential new STs, indicating that fish are natural hosts of Blastocystis. Marine fishes are also carriers of human STs and represent a likely limited source of zoonotic transmission. 13.8% of the marine mammals tested were colonized and 6 different STs were identified including 3 potential new STs. The risk of zoonotic transmission through marine mammals is insignificant due to the lack of repeated contact with humans. The present survey represents the first data regarding the prevalence and ST distribution of Blastocystis in marine fish and marine mammals and provides new insights into its genetic diversity, host range and transmission.

Exploring Micro-Eukaryotic Diversity in the Gut: Co-occurrence of Blastocystis Subtypes and Other Protists in Zoo Animals

Blastocystis is a genetically diverse microbial eukaryote thriving in the gut of humans and other animals. While Blastocystis has been linked with gastrointestinal disorders, its pathogenicity remains controversial. Previous reports have suggested that one out of six humans could be carrying Blastocystis in their gut, while the numbers could be even higher in animals. Most studies on Blastocystis are either exclusively targeting the organism itself and/or the associated prokaryotic microbiome, while co-occurrence of other microbial eukaryotes has been mainly ignored. Herein, we aimed to explore presence and genetic diversity of Blastocystis along with the commonly occurring eukaryotes Cryptosporidium, Eimeria, Entamoeba and Giardia in the gut of asymptomatic animals from two conservation parks in the United Kingdom. Building upon a previous study, a total of 231 fecal samples were collected from 38 vertebrates, which included 12 carnivorous and 26 non-carnivorous species. None of the animals examined herein showed gastrointestinal symptoms. The barcoding region of the small subunit ribosomal RNA was used for subtyping of Blastocystis. Overall, 47% of animal species were positive for Blastocystis. Twenty six percent of samples carried more than one subtypes, including the newly identified hosts Scottish wildcat, bongo and lynx. Fifty three percent of samples carried at least another microbial eukaryote. Herewith, we discuss potential implications of these findings and the increasingly blurred definition of microbial parasites.

First subtyping of Blastocystis sp. from pet rodents in southwestern China

Blastocystis sp. is a common eukaryotic parasite, which infects humans as well as various other animals. To date, epidemiological data regarding the detection rate and distribution of Blastocystis sp. subtypes in pet rodents are lacking in China; the present study aims to fill this gap. A total of 503 fecal samples collected from pets in different locations in southwestern China were screened for the presence of Blastocystis sp. using a nested PCR amplification of SSU rRNA method. Forty-two samples (8.35%) tested positive for Blastocystis sp. colonization. Two subtypes of Blastocystis sp. were identified based on nucleotide sequence homology and phylogenetic analysis: Blastocystis ST4 was present in 41 samples, and Blastocystis ST17 was found in 1 sample. Our results revealed robust host preference of Blastocystis ST4 and confirmed that Blastocystis ST17 can also parasitize rodents.

•

This is the first survey of Blastocystis sp. from pet rodent in southwestern of China and that 503 rodents were surveyed.

•

Forty-two samples (8.35%) tested positive for Blastocystis sp. colonization.

•

Forty-one isolates were identified as subtype ST4 and one as ST17.

•

Subtype ST4 shows a robust host preference for rodents.

Prevalence of Blastocystis sp. infection in several hosts in Brazil: a systematic review and meta-analysis

BACKGROUND

Blastocystis sp. affects a wide variety of animals and is the most common protozoan in human fecal samples with potential pandemic distribution. In the present study, a systematic review and meta-analysis were conducted to determine the prevalence and distribution of Blastocystis sp. in different classes of hosts in Brazil.

METHODS

Studies that analyzed hosts of various classes, including humans, domestic animals, wild animals or captive animals, were considered. The pooled prevalence of Blastocystis sp. infection was estimated by random effects models.

RESULTS

For humans, similar prevalence rates were found for males (31.0%, 95% CI: 17.0-45.0%; weight 10%) and females (28.0%, 95% CI: 16.0-41.0%; weight 10%); the state of Mato Grosso do Sul showed the highest prevalence, with 41.0% positivity (95% CI: 36.0-46.0%; weight 2.9%). The prevalence among immunocompromised patients was 5.0% (95% CI: 3.0-7.0%; weight 10%), and the most common cause of immunosuppression was hemodialysis, with 23.0% (95% CI: 17.0-29.0%; weight 12.4%). Among classifications according to interaction with humans, wild and domestic animals presented values of 19.0% (95% CI: 7.0-31.0%; weight 42.6%) and 17.0% (95% CI: 13.0-21.0%; weight 29.6%), respectively. Among these animals, mammals (39.0%, 95% CI: 21.0-56.0%; weight 47.3%) and birds (18.0%, 95% CI: 10.0-27.0%; weight 39.3%) exhibited the highest prevalence. Phylogenetic analysis of Blastocystis sp. revealed greater genetic diversity for clades of subtypes (STs) ST1, ST2 and ST3.

CONCLUSIONS

The overall prevalence of Blastocystis sp. in the Brazilian human population was 24%, which reflects the reality in the South, Southeast and Midwest regions, where prevalence rates of up to 40% were found. Among animals, mammals and birds exhibited the highest prevalence.

Prevalence and subtypes of Blastocystis sp. infection in zoo animals in three cities in China

Blastocystis is a highly prevalent eukaryotic parasite of many animals and humans worldwide. It can compromise the gastrointestinal tract and cause gastrointestinal symptoms, constituting a serious threat to human health and animal growth. Many animals are potential sources of Blastocystis infection in humans. However, limited data are available regarding the prevalence and subtype distribution of Blastocystis infection among zoo animals in China. Therefore, the present study examined the prevalence and subtypes of Blastocystis in zoo animals in Hangzhou, Dalian, and Suzhou cities, China. Of 450 fecal samples from zoo animals, 27 (6.0%) were PCR-positive for Blastocystis, with 7.7% (8/104), 11.3% (7/62), 16.7% (3/18), 1.8% (2/114), 6.3% (1/16), 9.5% (2/21), and 3.6% (4/109) in artiodactyla, aves, rodentia, nonhuman primates, perissodactyla, marsupialia, and carnivora, respectively. Significant differences in the prevalence of Blastocystis were found among different animal groups (P < 0.05). Sequence analysis showed 7 known subtypes (ST2, ST4, ST5, ST7, ST8, ST10, and ST14) of Blastocystis in the present study, with ST10 (10/27) as the predominant subtype in all three of the examined zoos. To our knowledge, this is the first report of Blastocystis infection in Damaliscus dorcas, Cervus elaphus, Macropus rufogriseus, Grus japonensis, Trichoglossus haematodus, Panthera tigris ssp. tigris (white), Panthera tigris ssp. altaica, Lycaon pictus, Suricata suricatta, and Dolichotis patagonum in China. These results demonstrate the presence of Blastocystis infection in zoo animals and provided baseline data for preventing and controlling Blastocystis infection in zoo animals and humans in China.

Molecular characterization of Blastocystis sp. in captive wildlife in Bangladesh National Zoo: Non-human primates with high prevalence and zoonotic significance

Blastocystis sp. is a protozoan parasite, commonly found in the gastrointestinal tracts of animals and humans globally. The parasitic species has wide genetic diversity. Currently the mammalian and avian isolates of the parasite are grouped into 17 well known subtypes (STs), of which ten (ST1-ST9, ST12) are reported in humans. To assess the genetic diversity of Blastocystis sp. in wildlife, a total of 200 fresh fecal samples were collected from 32 mammalian wildlife species in Bangladesh National Zoo. Blastocystis sp. was screened and subtyped by PCR amplification and sequencing of the small subunit ribosomal RNA (SSU rRNA) gene. The minimum prevalence of Blastocystis sp. infection was 15.5% (31/200) in zoo animals. Eight out of 32 wildlife animal species (25.0%) were infected with Blastocystis sp. Among them, the occurrence of Blastocystis sp. was higher in non-human primates (NHPs) (31.8%) than that in herbivores (4.9%) and carnivores (0). Nucleotide sequence analysis of the SSU rRNA gene revealed seven different Blastocystis sp. subtypes, such as ST1, ST2, ST3, ST10, ST11, ST13 and ST14 in the wild animals. ST3 was the dominant subtype (41.9%, 13/31) being detected in NHPs. Of the 31 Blastocystis sp. isolates from the wild animals, 24 (77.4%) isolates belonged to the most common subtypes (ST1 to ST3) found in humans. This is the first molecular study of Blastocystis sp. in wild animals in Bangladesh. This study highlights the remarkable genetic diversity in Blastocystis sp. isolates from zoo animals and provides the first molecular evidence from spotted deer, gayal and grey langur. Due to circulation of large percentage of potentially zoonotic subtypes in the wild animals, there is a higher risk of zoonotic transmission of Blastocystis sp. in the zoo keepers and visitors.

Molecular genotyping of Blastocystis spp. in wild mammals from Mexico

Blastocystis spp. are common intestinal parasites found worldwide in humans and a wide range of animals. They exhibit extensive genetic diversity; currently, 17 subtypes (STs) and some groups called non-mammalian and avian STs (NMASTs) have been proposed. In addition, a large variety of animals have been reported as hosts of the parasite, and new hosts and STs are still being described. In this study, Blastocystis infection of wild animals in two sylvatic areas of Mexico was surveyed. Of one hundred twenty-four fecal samples, six were positive for Blastocystis: specifically, one sample from an opossum, one sample from a bat, and four samples from different species of rodents. ST4, ST17, and nucleotide sequences similar to Blastocystis lapemi were identified based on SSU rDNA sequences. To our knowledge, this is the first report to investigate species poorly or not previously evaluated for Blastocystis infection. Mammals having different niches and geographical distribution were infected with similar genetic type of Blastocystis, so that we suggest that local water or food sources could play an important role in Blastocystis transmission and ST maintenance in wild animals. Additionally, there are STs with scarce genetic variation, suggesting that they could be highly adapted to their hosts. These data contribute to our understanding of the host range and genetic diversity of Blastocystis.

Molecular Detection and Subtyping of Blastocystis in Korean Pigs

Blastocystis is one of the most commonly detected genera of protozoan parasites in the human intestines as well as the intestines of many other species such as pigs in several geographical regions worldwide. However, no studies have examined Blastocystis in pigs in Korea. In this study, PCR and nucleotide sequencing were performed to evaluate the genetic diversity and zoonotic potential of Blastocystis using pig fecal samples. We obtained 646 stool samples from groups of piglets, weaners, growers, finishers, and sows in Korea. A total of 390 Blastocystis-positive samples were identified, and the infection rate was 60.4%. The infection rates were significantly related to age and region. The 4 subtypes (STs) of Blastocystis confirmed by phylogenetic analysis were ST1, ST2, ST3, and ST5, indicating the high genetic diversity of Blastocystis in Korean pigs. ST5 was highly distributed in Korean pigs among detected STs in this study. Some sequences were closely related to those of Blastocystis isolated from humans. This is the first study of Blastocystis in pigs in Korea. Based on the results, Blastocystis is prevalent in Korean pigs. Although a small number of samples were obtained in some areas, the clinical development of Blastocystis infection in pigs and potential for human transmission should be further examined.

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.

Interactions Between Parasites and the Bacterial Microbiota of Chickens

Except for the important role coccidia have as predisposing factors of necrotic enteritis, the role parasites play in the dynamics of a healthy microbiota of chickens is not well explored. This review describes the interactions of relevant intestinal parasites of chickens with bacteria. Infection with Eimeria spp. favor the growth of Clostridium perfringens and suppress the growth of many other bacteria by increasing viscosity and passage time of the ingesta, and by causing lesions to the intestinal mucosa that improve the availability of nutrients for C. perfringens. Conversely, there are indications that bacteria influence the course of disease after infections with Eimeria spp. Not much is known about intestinal cryptosporidiosis in chickens, but results in mice show that the intestinal microbiota induces some resistance against infection with Cryptosporidium parvum and that the innate immune response triggered by infections with cryptosporidia might have an effect on other intestinal microbes. Histomonas meleagridis depend on bacteria in vitro, and in vivo it will cause lesions in chickens only in the presence of bacteria. Blastocystis spp. are very common in chickens, but there is no information about interactions with bacteria. In humans, there is evidence of the correlation of the detection of Blastocystis and changes in the intestinal microbiota. There are indications of interactions between Ascaridia galli and various bacteria in chickens and Ascaridia spp. of mammals are known to produce various types of antimicrobial molecules. However, often the underlying mechanisms of these interactions between parasites and bacteria remain unknown and only correlations but not causation can be established.

Bioinformatic analysis suggests potential mechanisms underlying parasitoid venom evolution and function

Hymenopteran parasitoid wasps are a diverse collection of species that infect arthropod hosts and use factors found in their venoms to manipulate host immune responses, physiology, and behaviour. Whole parasitoid venoms have been profiled using proteomic approaches, and here we present a bioinformatic characterization of the venom protein content from Ganaspis sp. 1, a parasitoid that infects flies of the genus Drosophila. We find evidence that diverse evolutionary processes including multifunctionalization, co-option, gene duplication, and horizontal gene transfer may be acting in concert to drive venom gene evolution in Ganaspis sp.1. One major role of parasitoid wasp venom is host immune evasion. We previously demonstrated that Ganaspis sp. 1 venom inhibits immune cell activation in infected Drosophila melanogaster hosts, and our current analysis has uncovered additional predicted virulence functions. Overall, this analysis represents an important step towards understanding the composition and activity of parasitoid wasp venoms.

First report on the prevalence and subtype distribution of Blastocystis sp. in dairy cattle in Lebanon and assessment of zoonotic transmission

Blastocystis sp. is frequently identified in a wide range of animal hosts, including bovids. Because of its burden and zoonotic potential, this parasite has been sought in domestic cattle from various countries, since this livestock may also represent a possible reservoir of human infection. However, epidemiological data regarding the prevalence and ST distribution of Blastocystis sp. in this animal group is lacking in Lebanon. Therefore, faecal samples were collected from a total of 254 dairy cattle raised on 55 farms located in the North Lebanon region and screened for the presence of the parasite by quantitative real-time PCR. The overall prevalence of Blastocystis sp. was shown to reach 63.4% in cattle livestock. Sequence analysis of positive samples indicated the presence of seven STs, with predominance of ST10 (44.0%) and ST14 (36.8%) and lower proportions of ST2 (8.0%), ST1 (7.2%), ST5 (2.4%), ST3 and ST7 (0.8% each). This survey was the first conducted worldwide reporting ST2 and ST7 in domestic cattle and confirmed that ST10 and ST14 represent cattle-adapted STs in view of their high prevalence. Faecal samples from in-contact dairy farmers and patients hospitalised in the same Lebanese governorate who reported no contact with cattle livestock were also analysed for the presence of Blastocystis sp. The same three STs were identified in both human cohorts, with predominance of ST3, followed either by ST1 or ST2 depending of the group. No other STs, including ST10 or ST14, have been reported. Moreover, even though ST1, ST2 and ST3 were found to be common to dairy cattle and farmers cohorts, only one ST3 isolate showed 100% sequence identity between both hosts. Consequently, the presence and low prevalence of ST1, ST2, ST3, ST5 and ST7 identified herein in domestic cattle, most of which exhibit low host specificity, could be derived from occasional direct exposure to faecal material from human and non-human hosts or by ingestion of contaminated drinking water or food in the enclosure of the farms. Together with the absence of ST10 and ST14 in the human population, these data suggest that cattle play a negligible role as zoonotic reservoirs of Blastocystis sp.

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

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

Molecular detection and epidemiological risk factors associated with Cryptosporidium infection among cattle in Peninsular Malaysia

Enteric protozoa infection among cattle may pose a threat to productivity and survival leading to negative impacts on the livestock industry. A number of these pathogens are also known to be zoonotic and are of public health concern. Despite the importance of these enteric protozoa to both animal and human health, there remains a paucity of published information on the epidemiological risk factors that may be associated with bovine cryptosporidiosis in Southeast Asia. The present study was undertaken to determine the molecular prevalence and associated risk factors for Cryptosporidium infection among beef and dairy cattle in Peninsular Malaysia. Faecal samples were collected from 824 cattle in 39 farms (526 beef and 298 dairy) situated in 33 locations throughout the country, and subjected to PCR detection for Cryptosporidium using primers targeting the 18S SSUrRNA gene. Epidemiological variables including host, environment and management factors were subjected to univariate and multivariate logistic regression analyses to determine the potential risk factors for infection. The prevalence of Cryptosporidium among the cattle was 12.5%, with significant difference in the infection rate among the various breeds. There was no significant effect of gender, and both the beef and dairy cattle were at similar odds for infection. The younger cattle had a significantly higher infection rate compared to the older animals. Multivariate analysis revealed that deworming practice, distance to human settlement, geographical location (zone) and farm management system were significant risk factors associated with Cryptosporidium infection. The cattle that were reared on farms located in the northeast of the country, closest (≤200 m) to human settlements, reared extensively, and dewormed every four months were at highest risk of infection. The present study constitutes the first attempt to analyze the multivariable epidemiological risk factors involved in bovine cryptosporidiosis in Malaysia and in Southeast Asia. It is envisaged that the data obtained will facilitate better control and prevention measures for Cryptosporidium infection among cattle in the region. Due to the potential zoonotic nature of the infection, serious steps should be instituted for animal treatment and biohazard waste management on local cattle farms.

Molecular and descriptive epidemiology of intestinal protozoan parasites of children and their pets in Cauca, Colombia: a cross-sectional study

BACKGROUND

Parasitic infections, particularly those caused by protozoa, represent a considerable public health problem in developing countries. Blastocystis, Giardia duodenalis, Cryptosporidium spp. and the Entamoeba complex (Entamoeba histolytica, Entamoeba dispar and Entamoeba moshkovskii) are the most common etiological causes of intestinal parasitic infections.

METHODS

We carried out a descriptive cross-sectional study in school-age children attending a daycare institution in commune eight of Popayán, Cauca (Southwest Colombia). A total of 266 fecal samples were collected (258 from children and eight from pets). Blastocystis, G. duodenalis, Cryptosporidium spp. and the Entamoeba complex were identified by microscopy, quantitative real-time PCR (qPCR) and conventional PCR. The concordance of qPCR and microscopy was assessed using the Kappa index. Molecular characterization was conducted to identify Blastocystis subtypes (18S), G. duodenalis assemblages (tpi and gdh) and Cryptosporidium species/subtypes (18S and GP60). Potential associations between intestinal parasitism and sociodemographic factors were examined using bivariate analyses.

RESULTS

A total of 258 fecal samples from children were analyzed by microscopy and 255 samples were analyzed by qPCR. The prevalence of Blastocystis was between 25.19% (microscopy) and 39.22% (qPCR), that of G. duodenalis was between 8.14% (microscopy) and 10.59% (qPCR), that of Cryptosporidium spp. was estimated at 9.8% (qPCR), and that of the Entamoeba complex was between 0.39% (conventional PCR) and 0.78% (microscopy). The concordance between microscopy and qPCR was very low. Blastocystis ST1 (alleles 4, 8, and 80), ST2 (alleles 11, 12, and 15), ST3 (alleles 31, 34, 36, 38,57, and 151), and ST4 (alleles 42 and 91), G. duodenalis assemblages AII, BIII, BIV and D, C. parvum subtype IIa and C. hominis subtype IbA9G3R2 were identified. The only identified member of the Entamoeba complex corresponded to E. histolytica. No statistically significant association was identified between parasitic infection and any sociodemographic variable.

CONCLUSION

This study revealed the usefulness of molecular methods to depict the transmission dynamics of parasitic protozoa in southwest Colombia. The presence of some of these protozoa in domestic animals may be involved in their transmission.

The influence of probiotic bacteria and human gut microorganisms causing opportunistic infections on Blastocystis ST3

BACKGROUND

Blastocystis subtype 3 is an intestinal protist present in humans throughout the world with a controversial pathogenic potential. It has been suggested that probiotic bacteria inhibit the multiplication of gut protozoans, while others are beneficial for their development. This study aimed to evaluate the efficacy of the lactic acid bacteria Lactobacillus rhamnosus, Lactococcus lactis and Enterococcus faecium in Blastocystis ST3 eradication and the relevance of the intestinal microorganisms Escherichia coli, Candida albicans and Candida glabrata in protozoan proliferation. Blastocystis xenic and axenic culture was co-incubated with the above-mentioned microorganisms and their cell free supernatants at different concentrations in vitro. The number of protozoan cells was counted every day.

RESULTS

Both experiments, with xenic and axenic cultures, showed Blastocystis inhibition by L. rhamnosus and L. lactis and their supernatants from the 2nd day of co-incubation. Furthermore, co-incubation with both E. faecium and E. coli showed a beneficial influence on Blastocystis during the first 2 days. Only after 3 days did the above-mentioned bacteria start to inhibit Blastocystis growth in both cultures. The supernatant containing the metabolites of E. coli was effective to a lesser degree. Compared to the control samples, co-incubation with both C. albicans and C. glabrata showed a faster decrease in Blastocystis proliferation, but this was not statistically significant.

CONCLUSIONS

This study has shown the potential of using L. rhamnosus and L. lactis, as well as E. faecium as a prophylactic treatment against Blastocystis colonization or as an additional treatment regimen in combination with standard drugs.

Medical Parasitology Taxonomy Update, 2016-2017

Parasite taxonomy continues to change as molecular and morphologic studies enhance our understanding of parasite relatedness. This minireview builds on the information provided in the last taxonomy update in this journal to summarize new and revised clinically relevant human parasite taxonomic changes that have occurred in 2016 and 2017.

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.

Blastocystis prevalence and subtypes in autochthonous and immigrant patients in a referral centre for parasitic infections in Italy

In this study we characterized the presence and subtype (ST1-ST4) of Blastocystis in patients attended at a referral center for tropical diseases in Northern Italy. We also, evaluated the organism's association with other intestinal parasites. Parasite screening was performed on 756 patients, from different geographical origins (namely, Italians, Africans, South Americans, Asian and non-Italian Europeans) in which Italians represented the largest group. Blastocystis was seen to be the most prevalent parasite in the study. Subtype 3 and 1 were the most frequently found in the Italians and Africans. Our data confirmed previous studies performed in Italy, in which ST3 proved to be the most prevalent subtype, but we highlighted also a high frequency of mixed subtypes, which were probably underestimated in former analyses. Interestingly, the mixed subtypes group was the most prevalent in all the analysed geographical areas. About half of our cases showed other co-infecting parasites and the most frequent was Dientamoeba fragilis. Our study confirms that, in Blastocystis infection, multiple subtypes and co-infecting parasites are very frequently present, in particular Dientamoeba fragilis.

A hospital qPCR-based survey of 10 gastrointestinal parasites in routine diagnostic screening, Marseille, France

There is a scarcity of recent epidemiological data on intestinal parasitic infections in France. We conducted a prospective study aimed at estimating the prevalence of 10 enteric parasites in Marseille, France, using real-time polymerase chain reaction (PCR)-based diagnosis. A total of 643 faeces from 488 patients referred to the Parasitology-Mycology Laboratory of the University Hospital of Marseille over a 6 months period were included. DNA was extracted using a semi-automated method. Parasites of interest were detected using singleplex quantitative PCRs (qPCRs). For positive samples, the Blastocystis subtype was determined by sequence analysis. During the study, the overall prevalence of enteric parasites was 17%. Blastocystis sp. was the most frequent species (10.5%), followed by Dientamoeba fragilis (2.3%) and Giardia intestinalis (2.3%). The prevalence of other parasites was <1% each. The ST3 Blastocystis subtype was predominant (43.6%) and the other subtypes identified were ST1, ST2, ST4 and ST6. This is the first time that a qPCR-based diagnosis has been used to survey the prevalence of 10 enteric parasites in a French University Hospital. This study confirms that fast, specific, sensitive and simultaneous detection in a single stool sample by qPCR clearly outperforms conventional microscopy-based diagnosis. Furthermore, qPCR is particularly well suited to surveying gastroenteritis agents.

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

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

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

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

Can the pyruvate: ferredoxin oxidoreductase (PFOR) gene be used as an additional marker to discriminate among Blastocystis strains or subtypes?

BACKGROUND

Blastocystis spp. are the most prevalent intestinal eukaryotes identified in humans, with at least 17 genetic subtypes (ST) based on genes coding for the small-subunit ribosomal RNA (18S). It has been argued that the 18S gene should not be the marker of choice to discriminate between STs of these strains because this marker exhibits high intra-genomic polymorphism. By contrast, pyruvate:ferredoxin oxidoreductase (PFOR) is a relevant enzyme involved in the core energy metabolism of many anaerobic microorganisms such as Blastocystis, which, in other protozoa, shows more polymorphisms than the 18S gene and thus may offer finer discrimination when trying to identify Blastocystis ST. Therefore, the objective of the present study was to assess the suitability of the PFOR gene as an additional marker to discriminate among Blastocystis strains or subtypes from symptomatic carrier children.

METHODS

Faecal samples from 192 children with gastrointestinal symptoms from the State of Mexico were submitted for coprological study. Twenty-one of these samples were positive only for Blastocystis spp.; these samples were analysed by PCR sequencing of regions of the 18S and PFOR genes. The amplicons were purified and sequenced; afterwards, both markers were assessed for genetic diversity.

RESULTS

The 18S analysis showed the following frequencies of Blastocystis subtypes: ST3 = 43%; ST1 = 38%; ST2 = 14%; and ST7 = 5%. Additionally, using subtype-specific primer sets, two samples showed mixed Blastocystis ST1 and ST2 infection. For PFOR, Bayesian inference revealed the presence of three clades (I-III); two of them grouped different ST samples, and one grouped six samples of ST3 (III). Nucleotide diversity (π) and haplotype polymorphism (θ) for the 18S analysis were similar for ST1 and ST2 (π = ~0.025 and θ = ~0.036); remarkably, ST3 showed almost 10-fold lower values. For PFOR, a similar trend was found: clade I and II had π = ~0.05 and θ = ~0.05, whereas for clade III, the values were almost 6-fold lower.

CONCLUSIONS

Although the fragment of the PFOR gene analysed in the present study did not allow discrimination between Blastocystis STs, this marker grouped the samples in three clades with strengthened support, suggesting that PFOR may be under different selective pressures and evolutionary histories than the 18S gene. Interestingly, the ST3 sequences showed lower variability with probable purifying selection in both markers, meaning that evolutionary forces drive differential processes among Blastocystis STs.

Mitochondrial Glycolysis in a Major Lineage of Eukaryotes

The establishment of the mitochondrion is seen as a transformational step in the origin of eukaryotes. With the mitochondrion came bioenergetic freedom to explore novel evolutionary space leading to the eukaryotic radiation known today. The tight integration of the bacterial endosymbiont with its archaeal host was accompanied by a massive endosymbiotic gene transfer resulting in a small mitochondrial genome which is just a ghost of the original incoming bacterial genome. This endosymbiotic gene transfer resulted in the loss of many genes, both from the bacterial symbiont as well the archaeal host. Loss of genes encoding redundant functions resulted in a replacement of the bulk of the host’s metabolism for those originating from the endosymbiont. Glycolysis is one such metabolic pathway in which the original archaeal enzymes have been replaced by bacterial enzymes from the endosymbiont. Glycolysis is a major catabolic pathway that provides cellular energy from the breakdown of glucose. The glycolytic pathway of eukaryotes appears to be bacterial in origin, and in well-studied model eukaryotes it takes place in the cytosol. In contrast, here we demonstrate that the latter stages of glycolysis take place in the mitochondria of stramenopiles, a diverse and ecologically important lineage of eukaryotes. Although our work is based on a limited sample of stramenopiles, it leaves open the possibility that the mitochondrial targeting of glycolytic enzymes in stramenopiles might represent the ancestral state for eukaryotes.

Extra-enteric Blastocystis infection in a duck

Cell structures morphologically consistent with Blastocystis were aspirated from a subcutaneous facial swelling in a 13-mo-old pet duck. On PCR analysis and sequencing, the organism was confirmed as Blastocystis sp. subtype 7. Blastocystis is a single-celled protist that is found in the intestinal tract of many species, including mammals, birds, reptiles, amphibians, and insects. A complete understanding of the lifecycle and pathogenesis of the parasite remains elusive. Blastocystis has been implicated in human and animal disease; however, its role is controversial given that it is commonly found among healthy gut microbiota. Infection with Blastocystis outside the intestinal tract has been reported only rarely in humans. Our case of subcutaneous Blastocystis infection in a duck is a novel presentation of a ubiquitous, generally asymptomatic, parasite or commensal of the intestinal tract.

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

BACKGROUND

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

RESULTS

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

CONCLUSIONS

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

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

INTRODUCTION

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

METHODS

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

RESULTS

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

DISCUSSION

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

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

Background

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

Methodology/main findings

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

Conclusions/significance

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

Prevalence and molecular characterization of Strongyloides stercoralis, Giardia duodenalis, Cryptosporidium spp., and Blastocystis spp. isolates in school children in Cubal, Western Angola

BACKGROUND

Human infections by the gastrointestinal helminth Strongyloides stercoralis and the enteric protozoans Giardia duodenalis, Cryptosporidium spp. and Blastocystis spp. are not formally included in the list of 20 neglected tropical diseases prioritised by the World Health Organization. Although largely underdiagnosed and considered of lower public health relevance, these infections have been increasingly demonstrated to cause significant morbidity and even mortality globally, particularly among children living in resource-poor settings.

METHODS

In this cross-sectional survey the prevalence, frequency and molecular diversity of S. stercoralis, G. duodenalis, Cryptosporidium spp. and Blastocystis spp. were investigated in a school children population in the province of Benguela (Angola). A total of 351 stool samples were collected during January to June 2015. The presence of S. stercoralis and G. duodenalis was confirmed by qPCR methods. Giardia duodenalis assemblages and sub-assemblages were determined by multilocus sequence-based genotyping of the glutamate dehydrogenase and β-giardin genes of the parasite. Detection and identification of Cryptosporidium and Blastocystis species and subtypes was carried out by amplification and sequencing of a partial fragment of the small-subunit ribosomal RNA gene of both protozoan. Analyses of risk factors potentially associated with the transmission of these pathogens were also conducted.

RESULTS

Prevalences of S. stercoralis, G. duodenalis, Cryptosporidium spp., and Blastocystis spp. were estimated at 21.4% (95% CI: 17.1-25.7%), 37.9% (95% CI: 32.8-43.0%), 2.9% (95% CI: 1.1-4.5%) and 25.6% (95% CI: 21.18-30.2%), respectively. Overall, 64.1% (225/351) of the children were infected by at least one of the pathogens investigated. Sequence analyses of the 28 G. duodenalis isolates that were successfully genotyped allowed the identification of sub-assemblages AI (14.3%), AII (14.3%), BIII (7.1%) and BIV (25.0%). Discordant typing results AII/AIII and BIII/BIV were identified in 7.1% and 14.3% of the isolates, respectively. A total of five additional isolates (17.9%) were identified as assemblage B. Three Cryptosporidium species including C. hominis (70%), C. parvum (20%) and C. canis (10%) were found circulating in the children population under study. A total of 75 Blastocystis isolates were assigned to the subtypes ST1 (30.7%), ST2 (30.7%), ST3 (36.0%), ST5 (1.3%) and ST7 (1.3%), respectively. Children younger than seven years of age had significantly higher risk of infections by protozoan enteropathogens (PRR: 1.35, P < 0.01), whereas being underweight seemed to have a protective effect against these infections (PRR: 0.74, P = 0.005).

CONCLUSIONS

The burden of disease attributable to human strongyloidiasis, giardiosis, cryptosporidiosis and blastocystosis in Angola is considerably higher than initially estimated in previous surveys. Surveillance and control of these infections should be jointly tackled with formally considered neglected tropical diseases in order to maximize effort and available resources. Our data also demonstrate the added value of using molecular diagnostic methods in high transmission areas.

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

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

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.

First report of Blastocystis infections in cattle in China

Blastocystis is one of the most common intestinal protists of humans and can also infect a variety of other mammals and birds. Blastocystis infections and subtype distribution in cattle have been documented, while nothing is known about those in China. Herein, a total of 526 dairy cattle from northeast China were sampled and investigated for the prevalence and genetic characteristics of Blastocystis and the potential role of bovine animals in zoonotic transmission of Blastocystis. The parasite was identified in 54 (10.3%) fecal specimens by nested PCR and DNA sequencing of the small subunit ribosomal RNA gene. Sequence analysis enabled identification of four Blastocystis subtypes (STs). Among those, subtype ST10 (75.9%, 41/54) has the highest frequency, followed by ST14 (18.5%, 10/54), ST4 (3.7%, 2/54), and ST5 (1.9%, 1/54). High prevalence and widespread distribution of ST10 and ST14 in cattle observed herein, together with analysis of their host distribution patterns in earlier studies, indicated some host-adapted potential in the two subtypes. The identification of human-pathogenic subtypes ST4 and ST5 might imply a potential zoonotic risk of cattle origin. This is the first study exploring the prevalence and genetic characteristics of Blastocystis in cattle in China. The host range of subtype ST4 was extended. The findings of this study should be helpful for a better understanding of the epidemiology and public health potential of Blastocystis.

Extreme genome diversity in the hyper-prevalent parasitic eukaryote Blastocystis

Blastocystis is the most prevalent eukaryotic microbe colonizing the human gut, infecting approximately 1 billion individuals worldwide. Although Blastocystis has been linked to intestinal disorders, its pathogenicity remains controversial because most carriers are asymptomatic. Here, the genome sequence of Blastocystis subtype (ST) 1 is presented and compared to previously published sequences for ST4 and ST7. Despite a conserved core of genes, there is unexpected diversity between these STs in terms of their genome sizes, guanine-cytosine (GC) content, intron numbers, and gene content. ST1 has 6,544 protein-coding genes, which is several hundred more than reported for ST4 and ST7. The percentage of proteins unique to each ST ranges from 6.2% to 20.5%, greatly exceeding the differences observed within parasite genera. Orthologous proteins also display extreme divergence in amino acid sequence identity between STs (i.e., 59%-61% median identity), on par with observations of the most distantly related species pairs of parasite genera. The STs also display substantial variation in gene family distributions and sizes, especially for protein kinase and protease gene families, which could reflect differences in virulence. It remains to be seen to what extent these inter-ST differences persist at the intra-ST level. A full 26% of genes in ST1 have stop codons that are created on the mRNA level by a novel polyadenylation mechanism found only in Blastocystis. Reconstructions of pathways and organellar systems revealed that ST1 has a relatively complete membrane-trafficking system and a near-complete meiotic toolkit, possibly indicating a sexual cycle. Unlike some intestinal protistan parasites, Blastocystis ST1 has near-complete de novo pyrimidine, purine, and thiamine biosynthesis pathways and is unique amongst studied stramenopiles in being able to metabolize α-glucans rather than β-glucans. It lacks all genes encoding heme-containing cytochrome P450 proteins. Predictions of the mitochondrion-related organelle (MRO) proteome reveal an expanded repertoire of functions, including lipid, cofactor, and vitamin biosynthesis, as well as proteins that may be involved in regulating mitochondrial morphology and MRO/endoplasmic reticulum (ER) interactions. In sharp contrast, genes for peroxisome-associated functions are absent, suggesting Blastocystis STs lack this organelle. Overall, this study provides an important window into the biology of Blastocystis, showcasing significant differences between STs that can guide future experimental investigations into differences in their virulence and clarifying the roles of these organisms in gut health and disease.

Blastocystis: how do specific diets and human gut microbiota affect its development and pathogenicity?

Blastocystis is an enteric parasite that inhabits the gastrointestinal tract of humans and many animals. This emerging parasite has a worldwide distribution. It is often identified as the most common eukaryotic organism reported in human fecal samples. This parasite is recognized and diagnosed more often than ever before. Furthermore, some strains develop resistance against currently recommended drugs, such as metronidazole; therefore, the use of natural remedies or special diets has many positive aspects that may address this problem. The goal of this review is to compare natural treatments and various diets against the efficacy of drugs, and describe their influence on the composition of the gut microbiota, which affects Blastocystis growth and the occurrence of symptoms. This article reviews important work in the literature, including the classification, life cycle, epidemiology, pathogenesis, pathogenicity, genetics, biology, and treatment of Blastocystis. It also includes a review of the current knowledge about human gut microbiota and various diets proposed for Blastocystis eradication. The literature has revealed that garlic, ginger, some medical plants, and many spices contain the most effective organic compounds for parasite eradication. They work by inhibiting parasitic enzymes and nucleic acids, as well as by inhibiting protein synthesis. The efficacy of any specific organic compound depends on the Blastocystis subtype, and, consequently, on its immunity to treatment. In conclusion, the article discusses the findings that human gut microbiota composition triggers important mechanisms at the molecular level, and, thus, has a crucial influence on the parasitic pathogenicity.

Molecular epidemiology of blastocystosis in Malaysia: does seasonal variation play an important role in determining the distribution and risk factors of Blastocystis subtype infections in the Aboriginal community?

BACKGROUND

Alternating wet and dry seasons may play an important role in the acquisition and distribution of Blastocystis subtype infection in the tropics. This cross-sectional study was therefore conducted to provide the prevalence of Blastocystis and to determine the potential risk factors associated with each subtype during the wet and dry seasons in the Aboriginal community, Pahang, Malaysia.

METHODS

A total of 473 faecal samples were collected: 256 (54.1%) and 217 (45.9%) samples were obtained during the wet (October-November 2014) and the dry season (June 2015), respectively. All fresh faecal samples were subjected to molecular analysis for subtype and allele identification.

RESULTS

Of the 473 samples, 42.6% and 37.8% were positive for Blastocystis ST1, ST2, ST3 and ST4 during wet and dry seasons, respectively. Prevalence of Blastocystis ST1 was significantly higher during the wet season compared to the dry season (Z = 2.146, P < 0.05). Analysis of the association of each Blastocystis subtype with socioeconomic characteristics showed the presence of other family members infected with Blastocystis ST3 and the use of stored river water for domestic activities were the significant risk factors for Blastocystis ST3 infections during both seasons. Untreated water supply and low monthly household income (less or equal to RM 500) were the other significant risk factors for Blastocystis ST3 infections during wet and dry season, respectively. The presence of other family members with Blastocystis ST1 and ST2 was the only significant risk factor associated with ST1 and ST2 infections during both seasons. We hypothesise that transmission of Blastocystis ST1, ST2 and ST3 occurred from person to person during both seasons. The waterborne transmission was also identified as a mode of transmission of Blastocystis ST3.

CONCLUSION

The significant risk factors identified in this study were important in the dynamic transmission of Blastocystis infections during both seasons. Provision of treated water supply and health education are affirmative actions to be taken to control Blastocystis infections in this community.

Blastocystis in Côte d'Ivoire: molecular identification and epidemiological data

Blastocystis is an enteric protozoan infecting humans and animals in both developed and developing countries at all latitudes. Despite this, data on Blastocystis infection are not available for several geographical areas, including many African countries. In this study, a survey was conducted on Blastocystis among humans and domestic animals in rural and urban localities in Côte d'Ivoire, in order to investigate the prevalence, the subtype distribution, and the zoonotic potential in association with sociodemographic factors, seasonality, symptoms, and co-infections. A total of 110 fecal samples were collected from patients living in four localities. Molecular and phylogenetic analyses were conducted for Blastocystis detection and subtyping. Positive samples from symptomatic patients were tested by Luminex xTAG® Gastrointestinal Pathogen Panel (GPP) to evidence the presence of other common intestinal pathogens. Overall, a prevalence of 58.2% was observed in humans and subtypes ST1(50.0%), ST2 (22.0%) and ST3 (28.1%) were identified. The prevalence values varied significantly among the sites but not in relation to the subtype. The seasonal rains significantly increase the infection rate in all localities. No significant differences in the ST distribution between asymptomatic and symptomatic subjects were observed. As regard the zoonotic transmission, an additional sampling was conducted in another village where fecal samples were simultaneously collected from humans and animals. Blastocystis STs 1-3 and ST7 were identified in eight humans and four chickens, respectively. This study provides the first exhaustive data on the prevalence and molecular epidemiology of Blastocystis in Côte d'Ivoire.

Predominance and association risk of Blastocystis hominis subtype I in colorectal cancer: a case control study

Background

Blastocystis, a genetically diverse intestinal parasite with controversial pathogenic potential, has increasingly been incriminated for diarrheal illness in immunocompromised individuals including colorectal cancer (CRC) patients. The aim of the current study was to assess the possible association between Blastocystis infection and CRC condition in Makkah, Saudi Arabia (KSA).

Methods

Stool samples were collected from 80 non-cancer (NC) and 138 cancer subjects including 74 CRC patients and 64 patients with other cancers outside gastrointestinal tract (COGT). Molecularly confirmed Blastocystis isolates were genetically grouped and subtyped using multiplex polymerase chain reaction with restriction fragment length polymorphism (PCR-RFLP) and sequence-tagged site primers-based PCR (PCR-STS), respectively.

Results

Blastocystis hominis were confirmed in 29.7, 25 and 15% among CRC, COGT and NC patients, respectively. Obtained Blastocystis isolates were initially categorized into 2 groups (A and C), which were subsequently subtyped into 3 different subtypes; subtype-I (38%), subtype-II (44%) and subtype-V (22%). Interestingly, subtype-I was the most predominantly detected subtype (54.5%) among CRC patients with a significant association risk (COR 7.548; 95% CI: 1.629–34.987; P = 0.004).

Conclusion

To the best of our knowledge, the current study is the first to provide genetic insights on the prevalence of Blastocystis hominis among CRC patients in Makkah, KSA. Moreover, the study suggests for a possible association between subtype-I of Blastocystis hominis and CRC, which could indicate a potential influence of Blastocystis on CRC condition. Further studies are required to confirm this association risk and to investigate the possible underlying mechanism of postulated carcinogenic influence of Blastocystis hominis subtype-I.

Electronic supplementary material

The online version of this article (doi:10.1186/s13027-017-0131-z) contains supplementary material, which is available to authorized users.

PCR-based molecular characterization of Blastocystis hominis subtypes in southwest of Iran

Blastocystis hominis is the most common intestinal parasite found in humans and many other hosts. Pathogenicity of Blastocystis sp. remains controversial and it has been suggested that it may be associated with certain subtypes of organism. The aim of this study was to evaluate the molecular epidemiology of B. hominis and its subtype distribution in Ahvaz, southwest of Iran. During 2012-2014, a total of 481 samples were collected from patients referred to the medical laboratory centers in Ahvaz for stool examination. Samples were examined by wet mount, and genomic DNA was extracted from 50 positive samples. PCR was performed using seven primer pairs targeting the SSU rDNA gene and sequenced. 69 (14.35%) samples were found to be positive for B. hominis and the subtypes of 50 samples were identified. Five subtypes (STs) were identified, including: ST1 (22%), ST2 (6%), ST3 (40%), ST4 (2%), and ST5 (8%). 11 (22%) mixed infections were found, of which 5 were a mixture of ST3/ST4. Mixtures of ST1/ST3 and ST1/ST4 were 3, respectively. In this study people infected with ST3 showed the most gastrointestinal symptoms. This is the first study in the population of Ahvaz and indicates the high prevalence of ST3 in this area. The results suggest a possible association between this subtype and pathogenic potential of parasite.

Identification of Blastocystis subtypes in clinical stool samples from Sao Paulo City, Brazil

Blastocystis sp. is a protozoan commonly found in human and animal stool samples. Several pathogenic and zoonotic aspects of this organism are still unknown. The aim of the present study was to investigate Blastocystis subtypes (STs) in samples from patients of the Hospital das Clínicas of the Faculdade de Medicina at the Universidade de São Paulo (HC-FMUSP), Brazil. Blastocystis sp.-positive stool samples diagnosed at the Section of Parasitology of the Central Laboratory (HC-FMUSP) were used for DNA isolation. Polymerase chain reaction (PCR) was performed using specific primers targeting the small-subunit rRNA gene. Direct DNA sequencing of the PCR products was performed and the DNA sequences were then aligned and compared with other sequences obtained from the GenBank database. Phylogenetic analysis was used to identify STs and determine the phylogenetic relationships between the sequences. Four STs were identified: ST1 (22·5%), ST2 (12·5%), ST3 (60%) and ST6 (5%). In conclusion, ST3 was the most prevalent ST among the human isolates followed by ST1. The present study is one of the few providing STs data from the human population in South America. Determining ST prevalence in human samples may contribute to the monitoring of Blastocystis sp. infection transmission in endemic regions.

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.

Subtype analysis of Blastocystis isolates using SSU rRNA-DNA sequencing in rural and urban population in southern Turkey

Blastocystis is a common and emerging parasite often seen in many studies conducted in urban population, with scanty reports on rural communities. However, little is known about the public health significance of Blastocystis infection. A total of 28 Blastocystis isolates from 17 (17/28, 60.71%) patients living in rural area and 11 (11/28, 39.29%) patients living in urban area were screened with seven kinds of sequenced-tagged site primers for identification of subtype. PCR products were sequenced with same combination of primers using the BigDye Terminator V 3.1 cycle sequencing kit, as per the manufacturers' protocol on the 3730 DNA analyzer (Applied Biosystems, Carlsbad CA, USA). The cross-comparison of the Blastocystis sequences of samples were determined by the neighbor-joining method based on a distance matrix between sequence pairs to generate dendograms. The following subtypes were identified; subtype 1 (10/28, 35.7%), subtype 3 (7/28, 25.0%), subtype 2 (5/28, 17.8%), subtype 4 (3/28, 10.7%), subtype 5 (1/28, 3.6%), subtype 6 (1/28, 3.6%), and subtype 7 (1/28, 3.6%) in all DNA samples. The comparison of Blastocystis subtypes distribution among the patients from rural and urban area revealed subtype 5 (1/17, 5.9%), subtype 6 (1/17, 5.9%) and subtype 7 (1/17, 5.9%) from patients of rural area but not any of these subtypes in patients living urban area. This study is the first large-scale study to examine the occurrence of Blastocystis in Turkey to shed lights on the cosmopolitan distribution of Blastocystis subtypes in southern part of Turkey. Subtype 5, subtype 6 and subtype 7 were determined in only rural area. The findings of this study suggest that Blastocystis is transmitted from animal to human and possess a zoonotic potential.