Blastocystis sp. in Small Ruminants: A Universal Systematic Review and Meta-analysis

Molecular characterization and zoonotic potential of Entamoeba spp., Enterocytozoon bieneusi and Blastocystis from captive wild animals in northwest China

BACKGROUND

Parasites Entamoeba spp., Enterocytozoon bieneusi and Blastocystis are prevalent pathogens causing gastrointestinal illnesses in animals and humans. Consequently, researches on their occurrence, distribution and hosts are crucial for the well-being of both animals and humans. Due to the confined spaces and frequent interaction between animals and humans, animal sanctuaries have emerged as potential reservoirs for these parasites. In this study, the wildlife sanctuary near the Huang Gorge of the Qinling Mountains in northwest China is chosen as an ideal site for parasite distribution research, considering its expansive stocking area and high biodiversity.

RESULTS

We collected 191 fecal specimens from 37 distinct wildlife species and extracted genomic DNA. We identified these three parasites by amplifying specific gene regions and analyzed their characteristics and evolutionary relationships. All the parasites exhibited a high overall infection rate, reaching 90.05%. Among them, seven Entamoeba species were identified, accounting for a prevalence of 54.97%, with the highest infection observed in Entamoeba bovis. In total, 11 Enterocytozoon bieneusi genotypes were discovered, representing a prevalence of 35.08%, including three genotypes of human-pathogenic Group 1 and two novel genotypes (SXWZ and SXLG). Additionally, 13 Blastocystis subtypes were detected, showing a prevalence of 74.87% and encompassing eight zoonotic subtypes. All of the above suggests significant possibilities of parasite transmission between animals and humans.

CONCLUSIONS

This study investigated the occurrence and prevalence of three intestinal parasites, enhancing our understanding of their genetic diversity and host ranges in northwest China. Furthermore, the distribution of these parasites implies significant potential of zoonotic transmission, underscoring the imperative for ongoing surveillance and implementation of control measures. These efforts are essential to mitigate the risk of zoonotic disease outbreaks originating from wildlife sanctuary.

Large-Scale Molecular Epidemiological Survey of Blastocystis sp. among Herbivores in Egypt and Assessment of Potential Zoonotic Risk

Given the proven zoonotic potential of the intestinal protozoan Blastocystis sp., a fast-growing number of surveys are being conducted to identify potential animal reservoirs for transmission of the parasite. Nevertheless, few epidemiological studies have been conducted on farmed animals in Egypt. Therefore, a total of 1089 fecal samples were collected from herbivores (sheep, goats, camels, horses, and rabbits) in six Egyptian governorates (Dakahlia, Gharbia, Kafr El Sheikh, Giza, Aswan, and Sharqia). Samples were screened for the presence of Blastocystis sp. by real-time PCR followed by sequencing of positive PCR products and phylogenetic analysis for subtyping of the isolates. Overall, Blastocystis sp. was identified in 37.6% of the samples, with significant differences in frequency between animal groups (sheep, 65.5%; camels, 62.2%; goats, 36.0%; rabbits, 10.1%; horses, 3.3%). Mixed infections were reported in 35.7% of the Blastocystis sp.-positive samples. A wide range of subtypes (STs) with varying frequency were identified from single infections in ruminants including sheep (ST1-ST3, ST5, ST10, ST14, ST21, ST24, ST26, and ST40), goats (ST1, ST3, ST5, ST10, ST26, ST40, ST43, and ST44), and camels (ST3, ST10, ST21, ST24-ST26, ST30, and ST44). Most of them overlapped across these animal groups, highlighting their adaptation to ruminant hosts. In other herbivores, only three and two STs were evidenced in rabbits (ST1-ST3) and horses (ST3 and ST44), respectively. The greater occurrence and wider genetic diversity of parasite isolates among ruminants, in contrast to other herbivores, strongly suggested that dietary habits likely played a significant role in influencing both the colonization rates of Blastocystis sp. and ST preference. Of all the isolates subtyped herein, 66.3% were reported as potentially zoonotic, emphasizing the significant role these animal groups may play in transmitting the parasite to humans. These findings also expand our knowledge on the prevalence, genetic diversity, host specificity, and zoonotic potential of Blastocystis sp. in herbivores.

Molecular investigation of Blastocystis sp. infections in wild rodents from the Inner Mongolian Autonomous Region and Liaoning province, China: High prevalence and dominance of ST4

Wild rodents are key carriers of various human pathogens, including Blastocystis spp. Our study aimed to assess the prevalence and genetic characteristics of Blastocystis among wild rodents in the Inner Mongolian Autonomous Region and Liaoning Province of China. From November 2023 to February 2024, 486 rodents were captured in these regions. Fresh feces were collected from the intestines of each rodent for the isolation of DNA and PCR amplification of the vertebrate cytochrome b (cytb) gene to identify rodent species. Subsequently, PCR analysis and sequencing of the partial small subunit of the ribosomal RNA (rRNA) gene were utilized to detect Blastocystis in all fecal samples. Of the total samples, 27.4% (133/486) were found to be Blastocystis positive. The results revealed the presence of four species of rodents infected with Blastocystis, 32.3% (63/195) in Rattus norvegicus, 15.1% (16/106) in Mus musculus, 20.2% (18/89) in Apodemus agrarius, and 37.5% (36/96) in Cricetulus barabensis. Sequence analysis confirmed the existence of five Blastocystis subtypes: ST1 (n = 4), ST2 (n = 2), the ST4 (n = 125, the dominant subtype), ST10 (n = 1), and a novel ST (n = 1). The identified zoonotic subtypes (ST1, ST2, ST4, and ST10) highlight the possible role played by wild rodents in the transmission of Blastocystis to humans, thereby elevating the chances of human infection. Meanwhile, the discovery of novel sequences also provides new insights into the genetic diversity of this parasite.

Prevalence and Genetic Characterization of Giardia duodenalis and Blastocystis spp. in Black Goats in Shanxi Province, North China: From a Public Health Perspective

Blastocystis spp. and Giardia duodenalis are two prevalent zoonotic intestinal parasites that can cause severe diarrhea and intestinal diseases in humans and many animals. Black goat (Capra hircus) farming is increasingly important in China due to the remarkable adaptability, high reproductive performance, rapid growth rate, and significant economic value of black goats. A number of studies have indicated that black goats are the potential reservoir of multiple zoonotic protozoans in China; however, the prevalence and zoonotic status of G. duodenalis and Blastocystis spp. in black goats in Shanxi Province is still unknown. Thus, a total of 1200 fecal samples of black goats were collected from several representative regions at different altitudes in Shanxi Province and were examined for the presence and genotypes of G. duodenallis and Blastocystis spp. by amplifying the beta-giardin (bg), glutamate dehydrogenase (gdh), and triosephosphate isomerase (tpi) loci of G. duodenalis and SSU rRNA of Blastocystis spp. using PCR and sequence analysis methods, respectively. The overall prevalence of G. duodenalis and Blastocystis spp. in black goats in Shanxi Province were 7.5% and 3.5%, respectively. Two assemblages (B and E) of G. duodenalis and four subtypes (ST5, ST10, ST14, and ST30) of Blastocystis spp. were identified, with assemblage E and ST10 as the prevalent genotype and subtype in black goats, respectively. One novel multilocus genotype (MLG) was identified in MLG-E and was designated as MLG-E12. For both G. duodenalis and Blastocystis spp., the prevalence was significantly related to the region and age groups (p < 0.05). This is the first report on the prevalence of G. duodenalis and Blastocystis spp. in black goats in Shanxi Province. These results not only provide baseline data for the prevention and control of both parasites in black goats in Shanxi Province, but also enhance our understanding of the genetic composition and zoonotic potential of these two parasites.

First molecular subtyping and zoonotic significance of Blastocystis sp. in Dromedary (C. dromedarius) and Bactrian (C. bactrianus) camels in Iran: A molecular epidemiology and review of available literature

BACKGROUND

Blastocystis sp. is a zoonotic protozoan parasite, and there is limited information about its molecular prevalence and subtypes (STs) distribution in camels globally, especially in Iran.

OBJECTIVES

This study aimed to examine the prevalence, STs distribution, and zoonotic potential of Blastocystis sp. in one-humped and two-humped camels in Ardabil province, northwestern Iran.

METHODS

A PCR-sequencing tool using the SSU rRNA gene was employed to examine the occurrence and genetic variation of Blastocystis sp. in 150 faecal samples from Bactrian (Camelus bactrianus, 50 samples) and Dromedary (Camelus dromedarius, 100 samples) camels in Ardabil province.

RESULTS

The overall prevalence of Blastocystis sp. in camels was determined to be 12% (18/150) through microscopy and PCR analyses. Phylogenetically, this study identified three distinct zoonotic STs: ST7, ST10, and ST14. ST10 was the most prevalent, comprising 50% (9/18) of the isolated STs from camels. ST14 closely followed with 38.9% (7/18), while ST7 made up 11.1% (2/18) of the total STs. In brief, ST10, ST14, and ST7 represented 50% (7/14), 35.7% (5/14), and 14.3% (2/14) of the Blastocystis-positive cases in one-humped camels, respectively. Further, each of the ST10 and ST14 accounted for 50% (2/4) of the Blastocystis-positive samples in two-humped camels. An analysis of the available data reveals that out of the 37-44 identified Blastocystis STs, 15 (ST1-ST7, ST10, ST14, ST15, ST21, ST24, ST25, ST26, and ST30) have been reported in camels. The predominant STs observed are ST10 and ST14. Furthermore, among the 15 zoonotic STs (ST1-ST10, ST12-ST14, ST16, and ST23) of Blastocystis reported thus far, nine zoonotic STs (ST1-ST7, ST10, and ST14) have been found in camels.

CONCLUSIONS

These findings indicate that camels serve as a proper reservoir for a diverse array of Blastocystis STs and thereby can play a significant role in the transmission of this protozoan infection to humans, animals, and water reservoirs.

First molecular characterization of Blastocystis subtypes from domestic animals (sheep and cattle) and their animal-keepers in Ilam, western Iran: A zoonotic concern

A total of 360 fecal samples were randomly collected from 150 cattle, 150 sheep, and 60 humans (30 people with close animal contact and 30 individuals without close animal contact) at 10 farms in Ilam, western Iran from June 2022 to August 2023. All samples were directly examined for Blastocystis by zinc sulfate flotation, followed by microscopic observation. Positive samples were further subtyped using conventional PCR and sequencing methods. A mean prevalence of 5.3% (16/300) was estimated for Blastocystis infection among examined animals, with 6% and 4.7% for cattle and sheep, respectively. Among the people who had close and non-close animal contact, 16.7% (5/30) and 3.3% (1/30) were infected with Blastocystis, respectively (p < 0.05). All 22 positive samples were successfully sequenced at the SSU rRNA locus. Accordingly, Blastocystis isolates infecting domestic animals in Ilam belonged to the four STs (ST1-ST3, and ST10). Of the 16 animal isolates, nine sequences (four ST10, three ST3, and two ST1) were related to cattle, and seven sequences (three ST10, two ST3, and two ST2) were isolated from sheep. Among the six human isolates, ST3 was the most predominant ST, followed by STs 1, 2, 6, and 7 (one case each). Of note, ST1-ST3 were isolated in various farms both from animals and their breeders, which indicates the possible circulation of these STs between animal and human populations.

Subtypes of Blastocystis in Tibetan Antelope (Pantholops hodgsonii)

Blastocystis is a protist that is distributed in the gut tract of humans and animals. However, the reports about Blastocystis infection in Tibetan antelope are scarce. We collected 173 Tibetan antelope feces samples from Xinjiang, Qinghai and Xizang, and amplified the SSU rRNA gene of 600 bp region of Blastocystis in our research. Fifty-one samples in total were positive for Blastocystis, with all subtypes being ST31. The lowest prevalence of Blastocystis was observed in Xizang (2/20, 9.1%), followed by Qinghai (18/92, 16.4%), Xinjiang (31/61, 33.7%). The highest prevalence of Blastocystis in Tibetan antelope was detected during the summer was (19/30, 38.8%). This is the first research work regarding the Blastocystis subtypes ST31 in Tibetan antelope. Our research provides information for future researches on the distribution of this Blastocystis subtype and the control of Blastocystis infection.

Molecular detection and characterization of Blastocystis in herbivore livestock species in Portugal

Blastocystis is a ubiquitous intestinal protist in humans and animals worldwide. The traditional livestock free-roaming raising system in rural communities increases the risk of infection with contact with a wider range of pathogens transmitted via the faecal-oral route associated with that wildlife-livestock-human interface. However, no studies have been conducted to determine the occurrence and subtype distribution of Blastocystis in livestock in Portugal. Here, we collected 180 faecal samples from herbivore livestock (cattle, goats, horses, and sheep) in different regions of the country to investigate Blastocystis prevalence and subtype diversity using PCR and next-generation amplicon sequencing. Blastocystis was present in 40.6% (73/180; 95% CI: 33.31-48.11) of the samples (goats, 81.0%; sheep, 60.9%; cattle, 32.2%). None of the horse samples were Blastocystis-positive. Eighteen subtypes were detected (ST1-ST3, ST5-ST7, ST10, ST13, ST14, ST21, ST23-ST26, ST30, ST42-ST44). Mixed infections were detected in 97.3% of the Blastocystis-positive samples. Potentially zoonotic subtypes were identified in 75.0%, 96.4%, and 100% of the Blastocystis-positive specimens collected from cattle, sheep, and goats, respectively. These results demonstrate that cattle, sheep, and goats harbour a high diversity of Blastocystis subtypes in the study regions. Importantly, our data provide novel molecular evidence strongly suggesting that some Blastocystis STs/ST subgroups may have differential host specificity.

First Molecular Identification and Subtyping of Blastocystis sp. in the Most Consumed Edible Marine Fish of Iran: A Foodborne Concern

PURPOSE

The presence of Blastocystis sp. is commonly observed in humans and different animals, displaying a wide range of genetic variations with the discovery of multiple subtypes (STs). However, the prevalence and distribution of these STs in edible marine fish and marine mammals remain uncertain. This study marks the first survey conducted in Iran and the second global molecular investigation to examine the occurrence and STs distribution of Blastocystis in various species of edible marine fish.

METHODS

This study screened 200 fresh intestinal contents from 10 well-known fish species (Narrow-barred mackerel, Indo-pacific king mackerel, Tigertooth croaker, Silver pomfret, Black pomfret, Longtail tuna, John's snapper, Blackspotted croaker, Four-finger threadfin, and Javelin grunter) in southern Iran, caught in the Persian Gulf. All collected samples were evaluated by microscopy and SSU-PCR methods.

RESULTS

Based on both microscopy and PCR, the overall prevalence of Blastocystis sp. in evaluated fish species was 2% (4/200). In brief, Blastocystis sp. was reported from Narrow-barred mackerel [10% (2/20)], Silver pomfret [5% (1/20)], and Tigertooth croaker [5% (1/20)]. Interestingly, among infected fish species three zoonotic STs (ST1, ST2, and ST7) were identified. ST2 was the most predominant ST [50% (2/4)], followed by ST1 and ST7, one sample each [5% (1/20)].

CONCLUSION

Overall, the prevalence and STs distribution of Blastocystis in edible marine fish along with the possibility of its zoonotic transmission are still open to question and require extensive and more detailed studies.

Identification of Blastocystis spp. in Urban Rodents of Different Districts in Southwestern Iran: Subtype Distribution and Possible Zoonotic Potential

PURPOSE

Rodents are one of the most abundant and diverse species of mammals and have recently been identified as carriers of numerous human pathogens. The current study was conducted to assess the prevalence, subtype (STs) distribution, and zoonotic potential of Blastocystis spp. in various species of rodents in Shiraz, southwestern Iran.

METHODS

For this aim, a total of 120 fresh fecal samples were collected from Mus musculus (n = 40), Rattus norvegicus (n = 40), and Rattus rattus (n = 40) in various municipality districts of Shiraz (6 out of 10 districts) between February and November 2020. Upon detecting parasites using light microscopy, a DNA fragment of the Blastocystis SSU rDNA gene was amplified using conventional PCR.

RESULTS

By employing direct wet mount examination, 8 out of 120 fecal samples (6.7%; 2 from house mice, 3 from black rats, and 3 from brown rats) tested positive. Similarly, 5% (2/40) of house mice, 7.5% (3/40) of black rats, and 7.5% (3/40) of brown rats tested positive using the molecular method. Phylogenetic analysis revealed that the Blastocystis infecting different rodent species in Shiraz belonged to two potentially zoonotic STs (ST1 and ST4). Accordingly, rodents should not be overlooked as potential reservoirs of zoonotic Blastocystis infections. Different sampled urban districts and their statistical association with reported prevalence rates were analyzed separately.

CONCLUSION

 Overall, the issue of the frequency and ST distribution of Blastocystis in urban rodents of Iran is still open to question and for a proper understanding, wider and more comprehensive studies are needed.

Comparative molecular epidemiology, subtype distribution, and zoonotic potential of Blastocystis sp. in Equus animals (horses, donkeys, and mules) in northwestern Iran

A total of 500 fecal samples were collected from Equus animals in six different cities (Ardabil, Namin, Nir, Meshginshahr, Germi, and Khalkhal) of Ardabil Province, northwestern Iran, with 200 samples from horses, 200 from donkeys, and 100 from mules. Of the horse samples, 100 were from racing horses under special monitoring and care, while the remaining 100 were from non-racing horses, including those used for herding or in rural areas. All fecal samples were examined for the presence of Blastocystis sp. using PCR amplification of the SSU rRNA gene's barcode region after DNA extraction. The molecular prevalence of Blastocystis infection in Equus animals was 7.6% (38/500). Blastocystis was more common in horses [11.5% (23/200)] than in donkeys [5.5% (11/200)] and mules [4% (4/100)] (P > 0.05). Compared to racing horses [3% (3/100)], non-racing/rural horses [20% (20/100)] exhibited a substantially higher prevalence of Blastocystis (P < 0.05). The prevalence of Blastocystis in diarrheal samples and younger animals was remarkably higher than in formed samples and older animals, respectively (P < 0.05). No significant difference in Blastocystis infection prevalence was found between the genders of examined animals (P > 0.05). In Equus animals, 38 Blastocystis isolates included eight STs: ST10 [31.6% (12/38)], ST1 [21.1% (8/38)], ST2 [15.8% (6/38)], ST3 [10.5% (4/38)], ST4 [7.9% (3/38)], ST7 [5.2% (2/38)], ST14 [5.2% (2/38)], and ST6 [2.6% (1/38)]. These results suggest that Equus animals act as a proper reservoir for numerous Blastocystis STs, consequently playing a crucial part in the spread of this protozoan infection to humans, animals, and water reservoirs.

Prevalence and Genetic Characterization of Blastocystis in Sheep and Pigs in Shanxi Province, North China: From a Public Health Perspective

Blastocystis is a common zoonotic intestinal protozoan and causes a series of gastrointestinal symptoms in humans and animals via the fecal-oral route, causing economic losses and posing public health problems. At present, the prevalence and genetic structure of Blastocystis in sheep and pigs in Shanxi province remains unknown. Thus, the present study collected 492 sheep fecal samples and 362 pig fecal samples from three representative counties in northern, central and southern Shanxi province for the detection of Blastocystis based on its SSU rRNA gene. The results showed that the overall prevalence of Blastocystis in the examined sheep and pigs were 16.26% and 14.09%, respectively. Sequences analyses showed that four known subtypes (ST5, ST10, ST14 and ST30) in sheep and two subtypes (ST1 and ST5) in pigs were detected in this study, with ST5 being the predominate subtype among the study areas. Phylogenetic analysis showed that the same subtypes were clustered into the same branch. This study reveals that sheep and pigs in Shanxi province are hosts for multiple Blastocystis subtypes, including the zoonotic subtypes (ST1 and ST5), posing a risk to public health. Baseline epidemiological data are provided that help in improving our understanding of the role of zoonotic subtypes in Blastocystis transmission.

Prevalence and Subtype Distribution of Blastocystis in Tibetan Sheep in Qinghai Province, Northwestern China

Blastocystis is one of the most common intestinal protists in humans and a great number of animals, including sheep and goats. High prevalence and multiple subtypes of Blastocystis have been reported in sheep in several regions of China and elsewhere. However, there is a dearth of knowledge about Blastocystis in Tibetan sheep. A total of 761 fecal samples were collected from Tibetan sheep in seven counties of Qinghai Province, northwestern China, and were examined for the prevalence and subtypes of Blastocystis using molecular technology based on the partial small subunit ribosomal RNA gene of Blastocystis. The overall prevalence of Blastocystis in the investigated Tibetan sheep was 7.5% (57/761) using PCR and DNA Sanger sequencing, and differences in prevalence were observed among the ruminants from the seven counties (P < 0.01), and across four seasons (P < 0.01). Sequence analysis revealed five subtypes (ST14 (57.9%), ST10 (26.3%), ST12 (5.3%), ST21 (5.3%), and ST30 (5.3%)) of Blastocystis sp. in these Tibetan sheep, with ST14 as the predominant subtype. To our knowledge, this is the first report of Blastocystis colonization in Tibetan sheep.