Unapparent microsporidial infection among immunocompetent humans in the Czech Republic

Pet chinchillas (Chinchilla lanigera): Source of zoonotic Giardia intestinalis, Cryptosporidium ubiquitum and microsporidia of the genera Encephalitozoon and Enterocytozoon

The domestic chinchilla (Chinchilla lanigera) is kept as a pet and previous studies suggest that it may play an important role as a source of zoonotic parasites, including Giardia intestinalis, Cryptosporidium spp. and microsporidia. In this study, we examined the occurrence and genetic diversity of above mentioned parasites in pet chinchillas in the Czech Republic by PCR/sequencing of the 18S rRNA, TPI, and ITS genes. Of 149 chinchillas from 24 breeders, 91.3 % were positive for G. intestinalis, 8.1 % for Cryptosporidium spp., 2.0 % for Encephalitozoon spp., and 5.4 % for E. bieneusi. Molecular analyses revealed presence of G. intestinalis assemblage B, C. ubiquitum (XIIa family), E. bieneusi genotypes D, SCF2, and, CHN-F1, and E. intestinalis. The infection intensity of G. intestinalis determined by qRT-PCR reached up to 53,978 CPG, C. ubiquitum up to 1409 OPG, E. intestinalis up to 1124 SPG, and E. bieneusi up to 1373 SPG. Only two chinchillas with C. ubiquitum and five with G. intestinalis had diarrhoea at the time of the screening. Three chinchillas in the long-term study were consistently positive for G. intestinalis, with intermittent excretion of C. ubiquitum, E. intestinalis, and E. bieneusi over 25 weeks. The findings indicate that chinchillas are frequently infected with zoonotic parasitic protists, but that these infections rarely show clinical signs. The lack of visible signs could reduce the vigilance of pet owners when handling their chinchillas, increasing the risk of transmission within breeding groups and possibly to humans.

Molecular Detection of Cryptosporidium spp. and Microsporidia in Human and Animal Stool Samples

Cryptosporidium spp. and Microsporidia are opportunistic microorganisms with remarkable zoonotic transmission potential due to their capacity to infect humans and animals. The aim of this study was to evaluate the prevalence of these microorganisms in stool samples of animal and human origin. In total, 369 stool samples (205 from human patients with diarrhea and 164 of animal origin) were included in the study. Cryptosporidium spp. and Microsporidia presence were determined by using multiplex nested PCR. Positive results were analyzed by using Sanger sequencing of the amplicon, utilizing BLASTN and ClustalX software to confirm identification. Cryptosporidium spp. were found in 0.97% and 4.26% of human and animal samples, respectively. Enterocytozoon bieneusi was detected in human and animal stools in 6.82% and 3.05% of the samples, respectively. No associations were found when analyzing the presence of Cryptosporidium spp. and E. bieneusi and the demographic and clinical variables of patients and animals. This study demonstrates the presence of these microorganisms in human and animal samples from different species, and the most interesting findings are the detection of Cryptosporidium spp. in pets (e.g., rodents) that are not usually included in this type of study, and the identification of E. bieneusi in patients with diarrhea without underlying disease.

First molecular detection and characterization of Enterocytozoon bieneusi different genotypes in human patients from Italy

Enterocytozoon bieneusi is one of the 17 microsporidian species pathogenic to humans in low and high-income countries, inducing both symptomatic and asymptomatic intestinal infections, independently of the immunological condition of the infected individual. Faecal-oral transmission occurs in a broad hosts range, including several animal species, but the parasite's zoonotic potential remains still unclear. Few studies are available in Italy regarding E. bieneusi presence in humans and no data on its genetic variability are so far reported. In this investigation, through the ITSr RNA sequences analysis, we provided the first E. bieneusi molecular characterization from symptomatic patients in Italy. Faecal samples from 410 patients sent for routine analyses to the Unit of Parasitology, Policlinico Tor Vergata, Rome, and resulted positive for E. bieneusi to a cartridge-based molecular test for qualitative detection (Novodiag® Stool Parasites assay), were collected. DNA was extracted, endpoint PCR performed and then sequences obtained for 3/410 patients (0.7 %). Genotype A (N = 1), genotype C (N = 1) and genotype K (N = 1) were identified, all belonging to phylogenetic Group 1. One patient (identified as genotype A) showed positivity to the same genotype previously characterized after a two-month period. Additional investigations are required, within a One Health framework, to review the importance of a zoonotic potential linked to E. bieneusi in human populations, animals and environmental reservoirs worldwide.

Host-specific Cryptosporidium, Giardia and Enterocytozoon bieneusi in shelter dogs from central Europe

Cryptosporidium spp., Giardia intestinalis and microsporidia are unicellular opportunistic pathogens that can cause gastrointestinal infections in both animals and humans. Since companion animals may serve as a source of infection, the aim of the present screening study was to analyse the prevalence of these intestinal protists in fecal samples collected from dogs living in 10 animal shelters in central Europe (101 dogs from Poland and 86 from the Czech Republic), combined with molecular subtyping of the detected organisms in order to assess their genetic diversity. Genus-specific polymerase chain reactions were performed to detect DNA of the tested species and to conduct molecular subtyping in collected samples, followed by statistical evaluation of the data obtained (using χ2 or Fisher's tests). The observed prevalence was 15.5, 10.2, 1 and 1% for G. intestinalis, Enterocytozoon bieneusi, Cryptosporidium spp. and Encephalitozoon cuniculi, respectively. Molecular evaluation has revealed the predominance of dog-specific genotypes (Cryptosporidium canis XXe1 subtype; G. intestinalis assemblages C and D; E. cuniculi genotype II; E. bieneusi genotypes D and PtEbIX), suggesting that shelter dogs do not pose a high risk of human transmission. Interestingly, the percentage distribution of the detected pathogens differed between both countries and individual shelters, suggesting that the risk of infection may be associated with conditions typical of a given location.

Meta-analysis of the global prevalence and risk factors of Enterocytozoon bieneusi infection in pigs from 1999 to 2021

Enterocytozoon bieneusi (E. bieneusi), which is one of the most common microsporidia, has been identified as an important obligate intracellular pathogen that commonly colonizes in a variety of animal species and humans worldwide, including humans. In this study, the statistical analyses of E. bieneusi infection and prevalence were performed to clarify the relationship between different genotypes in different countries. The databases Chinese National Knowledge Infrastructure (CNKI), VIP Chinese Journal Database, Wanfang Data, PubMed, Web of Science and ScienceDirect were used for data collection. The research data were subjected to subgroup, univariate regression, and correlation, to reveal factors related to the high prevalence of E. bieneusi. A total of, 34 of the 498 articles published before April 2022 met the inclusion criteria. The global prevalence of E. bieneusi in pigs was 37.69% (5175/12672). The prevalence of E. bieneusi in nursery pigs was 58.87% (588/946). In developing countries and Asia, the highest prevalence of E. bieneusi in pigs were 37.62% (4752/11645) and 40.14% (4715/11345), respectively. Moreover, humans and pigs have been found to be infected with the same genotype of E. bieneusi in some cases, as evidenced by the consolidation of genotype information. The results showed that pigs are susceptible to E. bieneusi during the nursery period. The prevalence of E. bieneusi is high in developing countries, and its genotype prevalence varies in each country. Thus, it is essential to strengthen the health inspection of vulnerable groups and customs quarantine inspection.

E. hellem Ser/Thr protein phosphatase PP1 targets the DC MAPK pathway and impairs immune functions

Microsporidia are difficult to be completely eliminated once infected, and the persistence disrupts host cell functions. Here in this study, we aimed to elucidate the impairing effects and consequences of microsporidia on host DCs. Enterocytozoon hellem, one of the most commonly diagnosed zoonotic microsporidia species, was applied. In vivo models demonstrated that E. hellem-infected mice were more susceptible to further pathogenic challenges, and DCs were identified as the most affected groups of cells. In vitro assays revealed that E. hellem infection impaired DCs' immune functions, reflected by down-regulated cytokine expressions, lower extent of maturation, phagocytosis ability, and antigen presentations. E. hellem infection also detained DCs' potencies to prime and stimulate T cells; therefore, host immunities were disrupted. We found that E. hellem Ser/Thr protein phosphatase PP1 directly interacts with host p38α (MAPK14) to manipulate the p38α(MAPK14)/NFAT5 axis of the MAPK pathway. Our study is the first to elucidate the molecular mechanisms of the impairing effects of microsporidia on host DCs' immune functions. The emergence of microsporidiosis may be of great threat to public health.

Genetic diversity of Cryptosporidium spp., Encephalitozoon spp. and Enterocytozoon bieneusi in feral and captive pigeons in Central Europe

Cryptosporidium spp., Enterocytozoon bieneusi and Encephalitozoon spp. are the most common protistan parasites of vertebrates. The results show that pigeon populations in Central Europe are parasitised by different species of Cryptosporidium and genotypes of microsporidia of the genera Enterocytozoon and Encephalitozoon. A total of 634 and 306 faecal samples of captive and feral pigeons (Columba livia f. domestica) from 44 locations in the Czech Republic, Slovakia and Poland were analysed for the presence of parasites by microscopy and PCR/sequence analysis of small subunit ribosomal RNA (18S rDNA), 60 kDa glycoprotein (gp60) and internal transcribed spacer (ITS) of SSU rDNA. Phylogenetic analyses revealed the presence of C. meleagridis, C. baileyi, C. parvum, C. andersoni, C. muris, C. galli and C. ornithophilus, E. hellem genotype 1A and 2B, E. cuniculi genotype I and II and E. bieneusi genotype Peru 6, CHN-F1, D, Peru 8, Type IV, ZY37, E, CHN4, SCF2 and WR4. Captive pigeons were significantly more frequently parasitised with screened parasite than feral pigeons. Cryptosporidium meleagridis IIIa and a new subtype IIIl have been described, the oocysts of which are not infectious to immunodeficient mice, whereas chickens are susceptible. This investigation demonstrates that pigeons can be hosts to numerous species, genotypes and subtypes of the studied parasites. Consequently, they represent a potential source of infection for both livestock and humans.

Microsporidia (Encephalitozoon cuniculi) in Patients with Degenerative Hip and Knee Disease, Czech Republic

Total joint arthroplasty is a commonly used surgical procedure in orthopedics. Revision surgeries are required in >10% of patients mainly because of prosthetic joint infection caused by bacteria or aseptic implant loosening caused by chronic inflammation. Encephalitozoon cuniculi is a microsporidium, an obligate intracellular parasite, capable of exploiting migrating proinflammatory immune cells for dissemination within the host. We used molecular detection methods to evaluate the incidence of E. cuniculi among patients who had total hip or knee arthroplasty revision. Out of 49 patients, E. cuniculi genotypes I, II, or III were confirmed in joint samples from 3 men and 2 women who had implant loosening. Understanding the risks associated with the presence of microsporidia in periprosthetic joint infections is essential for proper management of arthroplasty. Furthermore, E. cuniculi should be considered a potential contributing cause of joint inflammation and arthrosis.

Microsporidia dressing up: the spore polaroplast transport through the polar tube and transformation into the sporoplasm membrane

Microsporidia are obligate intracellular parasites that infect a wide variety of hosts including humans. Microsporidian spores possess a unique, highly specialized invasion apparatus involving the polar filament, polaroplast, and posterior vacuole. During spore germination, the polar filament is discharged out of the spore forming a hollow polar tube that transports the sporoplasm components including the nucleus into the host cell. Due to the complicated topological changes occurring in this process, the details of sporoplasm formation are not clear. Our data suggest that the limiting membrane of the nascent sporoplasm is formed by the polaroplast after microsporidian germination. Using electron microscopy and 1,1'-dioctadecyl-3,3,3',3' tetramethyl indocarbocyanine perchlorate staining, we describe that a large number of vesicles, nucleus, and other cytoplasm contents were transported out via the polar tube during spore germination, while the posterior vacuole and plasma membrane finally remained in the empty spore coat. Two Nosema bombycis sporoplasm surface proteins (NbTMP1 and NoboABCG1.1) were also found to localize in the region of the polaroplast and posterior vacuole in mature spores and in the discharged polar tube, which suggested that the polaroplast during transport through the polar tube became the limiting membrane of the sporoplasm. The analysis results of Golgi-tracker green and Golgi marker protein syntaxin 6 were also consistent with the model of the transported polaroplast derived from Golgi transformed into the nascent sporoplasm membrane.IMPORTANCEMicrosporidia, which are obligate intracellular pathogenic organisms, cause huge economic losses in agriculture and even threaten human health. The key to successful infection by the microsporidia is their unique invasion apparatus which includes the polar filament, polaroplast, and posterior vacuole. When the mature spore is activated to geminate, the polar filament uncoils and undergoes a rapid transition into the hollow polar tube that transports the sporoplasm components including the microsporidian nucleus into host cells. Details of the structural difference between the polar filament and polar tube, the process of cargo transport in extruded polar tube, and the formation of the sporoplasm membrane are still poorly understood. Herein, we verify that the polar filament evaginates to form the polar tube, which serves as a conduit for transporting the nucleus and other sporoplasm components. Furthermore, our results indicate that the transported polaroplast transforms into the sporoplasm membrane during spore germination. Our study provides new insights into the cargo transportation process of the polar tube and origin of the sporoplasm membrane, which provide important clarification of the microsporidian infection mechanism.

Global prevalence and risk factors of Enterocytozoon bieneusi infection in humans: a systematic review and meta-analysis

Enterocytozoon bieneusi is one of the most important zoonotic pathogens. In this study, we present a systematic review and meta-analysis of the prevalence of human E. bieneusi infection in endemic regions and analyze the various potential risk factors. A total of 75 studies were included. Among 31,644 individuals tested, 2,291 (6.59%) were E. bieneusi-positive. The highest prevalence of E. bieneusi in the male population was 5.50%. The prevalence of E. bieneusi in different age groups was varied, with 10.97% in teenagers. The prevalence of E. bieneusi in asymptomatic patients (6.49%) is significantly lower than that in HIV-infected patients (11.49%), and in patients with diarrheal symptoms (16.45%). Rural areas had a higher rate (7.58%) than urban ones. The prevalence of E. bieneusi in humans was the highest (6.42%) at altitudes <10 m. Moreover, the temperate zone marine climate (13.55%) had the highest prevalence. A total of 69 genotypes of E. bieneusi have been found in humans. This is the first global study regarding E. bieneusi prevalence in humans. Not only people with low immunity (such as the elderly, children, people with HIV, etc.), but also people in Europe in temperate marine climates should exercise caution to prevent infection with E. bieneusi during contact process with animals.

High genotype diversity and zoonotic potential of Enterocytozoon bieneusi in yaks (Bos grunniens) from Ganzi Tibetan Autonomous Prefecture, Sichuan Province

Enterocytozoon bieneusi is a common pathogen in humans and various animals, threatening the breeding industry and public health. However, there is limited information on the molecular characteristics of E. bieneusi in yaks, an economically important animal mainly domesticated in the Qinghai Tibet Plateau in China. In the present study, nested PCR targeting the ITS gene region was applied to investigate the positive rates and genetic diversity of E. bieneusi in 223 faecal samples of yaks from three locations in Ganzi Tibetan Autonomous Prefecture, Sichuan Province. The total positive rate of E. bieneusi was 23.8% (53/223). Significant differences in positive rates were identified among yaks from three locations (χ2 = 8.535, p = 0.014) and four age groups (χ2 = 17.259, p = 0.001), with the highest positive rates in yaks from Yajiang and aged < 6 months, respectively. Sequence analysis identified seven known (EbpC, LW1, LQ10, PigEBITS5, ESH-01, J and BEB4) and five novel (Ganzi1-5) ITS genotypes. Phylogenetic analysis showed eight genotypes (EbpC, LW1, LQ10, PigEBITS5, ESH-01, Ganzi1, Ganzi2 and Ganzi4) in group 1 and three genotypes (J, BEB4 and Ganzi3) in group 2, indicating high genotype diversity and zoonotic potential of E. bieneusi in yaks from Ganzi. Considering the increasing zoonotic genotypes in yaks in the present study compared with previous findings, interventions should be developed to reduce the potential transmission of E. bieneusi between humans and animals.

Molecular detection of Enterocytozoon bieneusi in farmed Asiatic brush-tailed porcupines (Atherurus macrourus) and bamboo rats (Rhizomys pruinosus) from Hainan Province, China: Common occurrence, wide genetic variation and high zoonotic potential

We investigated the occurrence and genotypic diversity of E. bieneusi in farmed Asiatic brush-tailed porcupines and bamboo rats from Hainan Province, China. Four hundred and sixty-seven fresh feces were collected from 164 Asiatic brush-tailed porcupines and 303 bamboo rats. DNA extraction from the feces and genotyping of E. bieneusi were performed by the amplification of the internal transcribed spacer (ITS) region of rDNA of E. bieneusi using PCR. A neighbor-joining tree was constructed based on the sequences obtained here and other sequences of E. bieneusi genotypes stored in Genbank. The total rate of infection with E. bieneusi was 32.5% (152/467), with 14.6% (24/164) in Asiatic brush-tailed porcupines and 42.2% (128/303) in bamboo rats infected. Seventeen genotypes of E. bieneusi were identified including 12 known genotypes, i.e., D (n = 78), Henan-III (n = 21), SHW7 (n = 19), KIN-1 (n = 11), ETMK5 (n = 7), TypeIV (n = 4), EbpD (n = 2), EbpA (n = 1), EbpC (n = 1), S7 (n = 1), HNPL-III (n = 1), HNR-VII (n = 1), and five novel genotypes named as HNZS-I (n = 1) and HNHZ-I to HNHZ-IV (n = 1 per genotype). Phylogenetic analysis revealed that all the genotypes found here except genotype S7 fell into Group 1. The present study demonstrated a relatively high prevalence of E. bieneusi infection (32.5%) and a large genetic variation of E. bieneusi (seventeen genotypes) in farmed Asiatic brush-tailed porcupines and bamboo rats in Hainan, China. The high proportion (78.3%) of zoonotic genotypes identified in the animals investigated here suggests that there is the potential for zoonotic or cross-species transmission which may pose a serious public health threat in the area. Public education on the management of Asiatic brush-tailed porcupines and bamboo rats should be implemented in the investigated areas.

Prevalence and associated risk factors of intestinal parasites among schoolchildren in Ecuador, with emphasis on the molecular diversity of Giardia duodenalis, Blastocystis sp. and Enterocytozoon bieneusi

BACKGROUND

Intestinal helminths, including Soil-Transmitted Helminth (STH), and Gastrointestinal Protist (GP) infections are major contributors to the global burden of disease, particularly in low-income countries such Ecuador. Their epidemiology in these settings is largely unknown.

METHODOLOGY

This prospective cross-sectional study investigates the carriage of intestinal helminths, including STH, and GP in asymptomatic schoolchildren (3-11 years) in the Chimborazo and Guayas provinces, Ecuador. Single stool samples (n = 372) and epidemiological questionnaires on demographics and potential risk factors were collected from participating schoolchildren. Conventional microscopy examination was used as screening method, and molecular (PCR and Sanger sequencing) assays were used to further investigate the epidemiology of some GP. A multivariate logistic regression analysis was used to evaluate the strength of the association of suspected risk factors with the presence of helminths and GP.

PRINCIPAL FINDINGS

At least one intestinal parasite species was observed by microscopy in 63.2% (235/372) of the participating schoolchildren. Enterobius vermicularis (16.7%, 62/372; 95% CI: 13.0-20.9) and Blastocystis sp. (39.2%, 146/372; 95% CI: 34.2-44.2) were the most prevalent among helminths and GP, respectively. Assemblages A (50.0%), B (37.5%) and A+B (12.5%) were detected within Giardia duodenalis and ST3 (28.6%), ST1 and ST2 (26.2% each), and ST4 (14.3%) within Blastocystis sp. Three genotypes, two known (A: 66.7%; KB-1: 16.7%) and a novel (HhEcEb1, 16.7%) were identified within Enterocytozoon bieneusi. Municipality of origin, household overcrowding, and poor sanitation and personal hygiene habits were risk factors for childhood intestinal parasites colonization.

CONCLUSIONS/SIGNIFICANCE

Despite massive government drug administration programs, STH and GP infection remain a public health concern in paediatric populations living in poor-resource settings. Molecular analytical methods are required to better understand the epidemiology of these intestinal parasites. This study provides novel information on the occurrence of Blastocystis sp. and E. bieneusi genetic variants circulating in Ecuadorian human populations.

A mouse ear skin model to study the dynamics of innate immune responses against the microsporidian Encephalitozoon cuniculi

Microsporidia are obligate intracellular parasites related to fungi that cause severe infections in immunocompromised individuals. Encephalitozoon cuniculi is a microsporidian species capable of infecting mammals, including human and rodents. In response to microsporidian infection, innate immune system serves as the first line of defense and allows a partial clearance of the parasite via the innate immune cells, namely macrophages, neutrophils, dendritic cells, and Natural Killer cells. According to the literature, microsporidia bypass this response in vitro by modulating the response of macrophages. In order to study host-parasites interactions in vivo, we developed a model using the mouse ear pinna in combination with an intravital imaging approach. Fluorescent E. cuniculi spores were inoculated into the skin tissue to follow for the first time in real time in an in vivo model the recruitment dynamics of EGFP + phagocytic cells in response to the parasite. The results show that parasites induce an important inflammatory recruitment of phagocytes, with alterations of their motility properties (speed, displacement length, straightness). This cellular response persists in the injection zone, with spores detected inside the phagocytes up to 72 h post-infection. Immunostainings performed on ear tissue cryosections evoke the presence of developing infectious foci from 5 days post-infection, in favor of parasite proliferation in this tissue. Overall, the newly set up mice ear pinna model will increase our understanding of the immunobiology of microsporidia and in particular, to know how they can bypass and hijack the host immune system of an immunocompetent or immunosuppressed host.

Molecular Detection of Microsporidia in Rabbits (Oryctolagus cuniculus) in Tenerife, Canary Islands, Spain

Enterocytozoon bieneusi and Encephalitozoon spp. are microsporidia with zoonotic potential that have been identified in humans, as well as in a large group of wild and domestic animals. Several wildlife species have been studied as reservoirs of zoonotic microsporidia in mainland Spain, including the European rabbit (Oryctolagus cuniculus). Due to a lack of data on microsporidia infection in wildlife on the Canary Islands, the aim of this work was to analyze the prevalence and identify the species of microsporidia in rabbits in Tenerife. Between 2015 and 2017, a total of 50 fecal samples were collected from rabbits in eight municipalities of Tenerife, Canary Islands, Spain. Seven of the fifty samples (14%) were amplified using nested polymerase chain reaction (PCR) targeting the partial sequence of the 16S rRNA gene, the internal transcribed spacer (ITS) region, and the partial sequence of the 5.8S rRNA gene. Sanger sequencing reveals the presence of Encephalitozoon cuniculi genotype I in two samples (4%), and undescribed microsporidia species in five samples (10%). This study constitutes the first molecular detection and genotyping of E. cuniculi in rabbits in Spain.

Evaluation of the Bio-Evolution Microsporidia generic and typing real-time PCR assays for the diagnosis of intestinal microsporidiosis

Cases of intestinal microsporidiosis infection are underestimated and affect both immunocompromized and immunocompetent patients. Real-time PCR is superseding microscopic examination for its diagnosis in medical analysis laboratories. However, few manufacturers include microsporidia in their PCR panel for the diagnosis of infectious gastroenteritis. Here, we evaluated the performances of the real-time PCR assays microsporidia generic and microsporidia typing (Bio-Evolution, France) on the Rotor-Gene Q real-time PCR cycler (Qiagen, France). We included 45 negative and 44 positive stool samples for Enterocytozoon bieneusi (n = 34, with various genotypes), Encephalitozoon intestinalis (n = 4), Encephalitozoon hellem (n = 4), and Encephalitozoon cuniculi (n = 2). We also studied a four-year survey of an inter-laboratory quality control program including 9 centers that used this commercial assay. Sensitivity and specificity of the microsporidia generic assay were 86.4% and 93.3%, respectively. Encephalitozoon hellem and Encephalitozoon cuniculi were detected by the microsporidia generic PCR assay but not by the microsporidia typing PCR assay. These results were consistent with the results of the inter-laboratory quality control program. In conclusion, Bio-Evolution Real-time PCR assays are useful tools for intestinal microsporidiosis, but negative results for microsporidia typing assays require supplementary analyses to confirm E. hellem or E. cuniculi infections.

Seasonal distribution of Cryptosporidium spp., Giardia duodenalis and Enterocytozoon bieneusi in Tibetan sheep in Qinghai, China

Background

Cryptosporidium spp., Giardia duodenalis and Enterocytozoon bieneusi can cause important intestinal diseases in ruminants. However, data on the distribution of these three protozoan pathogens in Tibetan sheep are limited.

Methods

We collected 761 fecal samples from Tibetan sheep across four seasons in Qinghai Province, China, and screened the samples for Cryptosporidium spp., G. duodenalis and E. bieneusi using PCR-based sequence analysis of the genes encoding 18S ribosomal RNA, triosephosphate isomerase and the internal transcribed spacer, respectively.

Results

The positivity rates of Cryptosporidium spp., G. duodenalis and E. bieneusi in Tibetan sheep were 3.68% (28/761 samples), 1.58% (12/761) and 6.44% (49/761), respectively. Four species of Cryptosporidium were identified: C. xiaoi (n = 13 samples), C. ubiquitum (n = 8), C. bovis (n = 6) and C. ryanae (n = 1). Two G. duodenalis assemblages, namely the A (n = 2 samples) and E (n = 10) assemblages, were detected. Five zoonotic E. bieneusi genotypes were found: BEB6 (n = 21 samples), COS-I (n = 14), CHS3 (n = 11) and CGS1 (n = 2) from group 2, and PIGEBITS5 (n = 1) from group 1. Geographic differences in the distribution of E. bieneusi, and seasonal differences for all the three protozoan pathogens were noted.

Conclusions

Our results elucidate the prevalence and genetic diversity of these three pathogens in Tibetan sheep across different regions and seasons, including zoonotic pathogens such as C. ubiquitum, C. ryanae, G. duodenalis assemblage A and five genotypes of E. bieneusi.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05442-0.

Zoonotic Enterocytozoon bieneusi genotypes in free-ranging and farmed wild ungulates in Spain

Microsporidia comprises a diverse group of obligate, intracellular, and spore-forming parasites that infect a wide range of animals. Among them, Enterocytozoon bieneusi is the most frequently reported species in humans and other mammals and birds. Data on the epidemiology of E. bieneusi in wildlife is limited. Hence, E. bieneusi was investigated in eight wild ungulate species present in Spain (genera Ammotragus, Capra, Capreolus, Cervus, Dama, Ovis, Rupicapra, and Sus) by molecular methods. Faecal samples were collected from free-ranging (n = 1058) and farmed (n = 324) wild ungulates from five Spanish bioregions. The parasite was detected only in red deer (10.4%, 68/653) and wild boar (0.8%, 3/359). Enterocytozoon bieneusi infections were more common in farmed (19.4%, 63/324) than in wild (1.5%, 5/329) red deer. Eleven genotypes were identified in red deer, eight known (BEB6, BEB17, EbCar2, HLJD-V, MWC_d1, S5, Type IV, and Wildboar3) and three novel (DeerSpEb1, DeerSpEb2, and DeerSpEb3) genotypes. Mixed genotype infections were detected in 15.9% of farmed red deer. Two genotypes were identified in wild boar, a known (Wildboar3) and a novel (WildboarSpEb1) genotypes. All genotypes identified belonged to E. bieneusi zoonotic Groups 1 and 2. This study provides the most comprehensive epidemiological study of E. bieneusi in Spanish ungulates to date, representing the first evidence of the parasite in wild red deer populations worldwide. Spanish wild boars and red deer are reservoir of zoonotic genotypes of E. bieneusi and might play an underestimated role in the transmission of this microsporidian species to humans and other animals.

A multidisciplinary review about Encephalitozoon cuniculi in a One Health perspective

Encephalitozoon cuniculi is a microsporidian parasite mostly associated with its natural host, the rabbit (Oryctolagus cuniculus). However, other animals can be infected, like other mammals, birds, and even humans. Although it usually causes subclinical infection, it can also lead to encephalitozoonosis, a clinical disease characterized by neurological, ocular, and/or renal signs that can be even fatal, especially in immunocompromised individuals. Therefore, this multidisciplinary review contributes with updated information about the E. cuniculi, deepening in its molecular and genetic characterization, its mechanisms of infection and transmission, and its prevalence among different species and geographic locations, in a One Health perspective. Recent information about the diagnostic and therapeutic approach in the main host species and the prophylaxis and infection control measures currently suggested are also discussed.

Molecular Detection and Genotyping of Enterocytozoon bieneusi in Pigs in Shanxi Province, North China

Enterocytozoon bieneusi is a common opportunistic intestinal pathogen that can cause acute diarrhea in immunosuppressed humans and animals. Though E. bieneusi has been widely detected in pigs around the world, little is known of its prevalence and genotype distribution in pigs in Shanxi province, north China. In this study, a total of 362 fecal samples were collected from pigs in three representative counties in north, south, and central Shanxi province, China. The prevalence and genotypes of E. bieneusi were investigated by nested PCR amplification of the ribosomal internal transcribed spacer (ITS) region of the ribosomal RNA (rRNA) gene. Overall, the prevalence of E. bieneusi in pigs in Shanxi province was 54.70% (198/362). Statistical analysis showed the difference in prevalence was statistically significant between regions (χ2 = 41.94, df = 2, P &lt; 0.001) and ages (χ2 = 80.37, df = 1, P &lt; 0.001). In addition, 16 genotypes of E. bieneusi were identified in this study by sequence analysis of the ITS region, including 15 known genotypes (EbpC, EbpA, EbpB, pigEb4, PigEBITS5, I, Henan-I, G, WildBoar 7, SH10, EbpD, CHC5, PigSpEb1, PigSpEb2, and CHG19) and one novel genotype (designated as PigSX-1). Phylogenetic analysis revealed that 14 known genotypes and the novel genotype were clustered into Group 1, whereas genotype I belonged to Group 2. To the best of our knowledge, this is the first report on the prevalence and genotypes of E. bieneusi in pigs in Shanxi province. These findings enrich the genetic diversity of E. bieneusi and provide the baseline data for the prevention and control of E. bieneusi in pigs in the study regions.

Global molecular epidemiology of microsporidia in pigs and wild boars with emphasis on Enterocytozoon bieneusi: A systematic review and meta-analysis

BACKGROUND

Microsporidia are spore-forming intracellular pathogens with worldwide prevalence, causing emerging infections in humans and animals. Enterocytozoon bieneusi is a zoonotic species of microsporidia and is responsible for more than 90% of cases of microsporidiosis in humans and animals. Pigs and wild boars are important animal reservoirs of microsporidia. Hence, we aimed to estimate the global prevalence of microsporidia and genetic diversity of E. bieneusi in pigs and wild boars through a set of systematic review and meta-analysis (PRISMA) guidelines.

METHODS

Four databases (Web of Science, PubMed, Scopus and Google Scholar) were searched between January 1, 2000 and April 30, 2021. Regarding meta-analysis, the random-effect model was employed by forest plot with 95% confidence interval (CI).

RESULTS

After exclusion of irrelevant articles and duplication removal, 33 papers, including 34 datasets (30 datasets for domestic pigs and 4 for wild boars) finally meet the inclusion criteria to undergo meta-analysis. The pooled prevalence rates of microsporidia infection in domestic pigs and wild boars were 37.6% (95% CI: 30.8-44.9%) and 8.1% (95% CI: 2.1-26.8%), respectively. While, the pooled prevalence rates of E. bieneusi were 35% (95% CI: 28.4-42.2%) in domestic pigs and 10.1% (95% CI: 1.7-42.4%) in wild boars. The genotypes EbpA was the most reported genotype in domestic pigs and wild boars. Male animals had higher prevalence rates of microsporidia infection than females (27 vs. 17.4%, OR = 1.91; 95% CI, 0.77-4.71%).

CONCLUSION

This study indicates the important role of domestic pigs and wild boars as animal reservoir hosts of microsporidia. Thereby, strategies for control and prevention of these zoonotic pathogens should be designed in pigs and wild boars.

Prevalence and genotypes/subtypes of Enterocytozoon bieneusi and Blastocystis sp. in different breeds of cattle in Jiangxi Province, southeastern China

Enterocytozoon bieneusi and Blastocystis sp. are common zoonotic pathogens that parasitize in the small intestine of humans and animals, posing a threat to public health. However, little information is available on the prevalence and genotypes/subtypes of E. bieneusi and Blastocystis sp. in cattle in Jiangxi Province, southeastern China. In the present study, 556 fecal samples of cattle were collected from Nanchang city, Gao'an city, Xinyu city, and Ji'an city in Jiangxi Province. All samples were examined for the presence of E. bieneusi by nested PCR analysis of the ribosomal internal transcribed spacer (ITS) and Blastocystis sp. using PCR targeting the SSU rRNA gene. The overall prevalence of E. bieneusi and Blastocystis sp. was 5.4% (30/556) and 54.9% (305/556), respectively. The prevalence of E. bieneusi in dairy cattle, beef cattle, and buffaloes was 7.9% (13/165), 3.9% (11/283), and 5.6% (6/108), respectively. Eleven E. bieneusi genotypes were identified in this study, including six known genotypes, D (n = 10), I (n = 5), J (n = 4), IV (n = 4), N (n = 1), and BEB4 (n = 1), and five novel genotypes, JX-I to JX-V (n = 1), with genotype D as the predominant genotype in cattle. Phylogenetic analysis showed that six genotypes of E. bieneusi, D, IV, and JX-II to JX-V, were clustered into zoonotic group 1, whereas the remaining five genotypes belonged to group 2. Moreover, seven, seven, four, and five types were identified by multilocus sequence typing (MLST) at the MS1, MS3, MS4, and MS7 loci, respectively, forming three distinct multilocus genotypes (MLGs). In addition, the prevalence of Blastocystis sp. was 42.4% (70/165), 59.4% (168/283), and 62.0% (67/108) in dairy cattle, beef cattle, and buffaloes, respectively. Sequence analysis revealed that ST1, ST5, ST10, and ST14 of Blastocystis sp. were identified in these cattle, with ST10 being the major subtype. ST1 and ST5 are potential zoonotic subtypes. These findings have important implications for the control of E. bieneusi and Blastocystis sp. in cattle in Jiangxi Province.

Chronic Infections in Mammals Due to Microsporidia

Microsporidia are pathogenic organism related to fungi. They cause infections in a wide variety of mammals as well as in avian, amphibian, and reptilian hosts. Many microsporidia species play an important role in the development of serious diseases that have significant implications in human and veterinary medicine. While microsporidia were originally considered to be opportunistic pathogens in humans, it is now understood that infections also occur in immune competent humans. Encephalitozoon cuniculi, Encephalitozoon intestinalis, and Enterocytozoon bieneusi are primarily mammalian pathogens. However, many other species of microsporidia that have some other primary host that is not a mammal have been reported to cause sporadic mammalian infections. Experimental models and observations in natural infections have demonstrated that microsporidia can cause a latent infection in mammalian hosts. This chapter reviews the published studies on mammalian microsporidiosis and the data on chronic infections due to these enigmatic pathogens.

The Function and Structure of the Microsporidia Polar Tube

Microsporidia are obligate intracellular pathogens that were initially identified about 160 years ago. Current phylogenetic analysis suggests that they are grouped with Cryptomycota as a basal branch or sister group to the fungi. Microsporidia are found worldwide and can infect a wide range of animals from invertebrates to vertebrates, including humans. They are responsible for a variety of diseases once thought to be restricted to immunocompromised patients but also occur in immunocompetent individuals. The small oval spore containing a coiled polar filament, which is part of the extrusion and invasion apparatus that transfers the infective sporoplasm to a new host, is a defining characteristic of all microsporidia. When the spore becomes activated, the polar filament uncoils and undergoes a rapid transition into a hollow tube that will transport the sporoplasm into a new cell. The polar tube has the ability to increase its diameter from approximately 100 nm to over 600 nm to accommodate the passage of an intact sporoplasm and penetrate the plasmalemma of the new host cell. During this process, various polar tube proteins appear to be involved in polar tube attachment to host cell and can interact with host proteins. These various interactions act to promote host cell infection.

A Perspective on the Molecular Identification, Classification, and Epidemiology of Enterocytozoon bieneusi of Animals

The microsporidian Enterocytozoon bieneusi is an obligate intracellular pathogen that causes enteric disease (microsporidiosis) in humans and has been recorded in a wide range of animal species worldwide. The transmission of E. bieneusi is direct and likely occurs from person to person and from animal to person via the ingestion of spores in water, food, or the environment. The identification of E. bieneusi is usually accomplished by molecular means, typically using the sequence of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA. Currently, ~820 distinct genotypes of E. bieneusi have been recorded in at least 210 species of vertebrates (mammals, birds, reptiles, and amphibians) or invertebrates (insects and mussels) in more than 50 countries. In this chapter, we provide a perspective on (1) clinical aspects of human microsporidiosis; (2) the genome and DNA markers for E. bieneusi as well as molecular methods for the specific and genotypic identification of E. bieneusi; (3) epidemiological aspects of E. bieneusi of animals and humans, with an emphasis on the genotypes proposed to be zoonotic, human-specific, and animal-specific; and (4) future research directions to underpin expanded molecular studies to better understand E. bieneusi and microsporidiosis.

Molecular Detection and Genotyping of Enterocytozoon bieneusi in Black Goats (Capra hircus) in Yunnan Province, Southwestern China

Simple Summary

Enterocytozoon bieneusi is one of the most common parasites in human and animals, and a threat to public health. So far, no data are available for E. bieneusi prevalence and genotypes in black goats in Yunnan Province, Southwestern China. Therefore, the objective of this study was to detect the prevalence and genotypes of E. bieneusi by examining 907 fecal samples collected from 5 counties in Yunnan Province. Ninety-three fecal samples (10.3%) were E. bieneusi-positive by PCR amplification. Four new genotypes and 11 known genotypes were identified, and all genotypes considered to be the zoonotic potential. Phylogenetic analysis showed that all of these genotypes were allocated into the zoonotic groups of E. bieneusi indicating its zoonotic potential. These results indicated that effective strategies and measures must be taken to prevent and control E. bieneusi transmission to other animals and humans.

Abstract

Enterocytozoon bieneusi is a fungus-like protist that can parasitize in the intestines of humans and various animals causing a threat to public health. However, there has been no data for E. bieneusi prevalence and genotypes in black goats in Yunnan Province, Southwestern China. In this study, 907 fecal samples were collected from black goats in 5 counties from Yunnan Province. The prevalence and genotypes of E. bieneusi were examined by nested PCR amplification targeting the nuclear internal transcribed spacer (ITS). Multi-locus sequence typing (MLST) was used to further examine the potential occurrence of genetic segregation. The overall prevalence of E. bieneusi in black goats in Yunnan Province was 10.3% (93/907). Statistical analysis revealed that E. bieneusi prevalence was significantly associated with the region, age and gender of black goats (p < 0.001). Four new genotypes (CYG-1, CYG-2, CYG-3, CYG-4) and 11 known genotypes (CHG1, CHG2, CHG3, CHG5, CHG28, J, D, BEB6, Wildboar3, CD6, SDD1) of E. bieneusi were identified. At the microsatellite and minisatellite loci, 15, 2, 17, and 33 sequences were obtained, respectively, forming one new multi-locus genotype (MLG27). Phylogenetic analysis revealed that all 15 genotypes were clustered into group 1 and group 2, with zoonotic potential. This is the first report of E. bieneusi prevalence and genotypes in black goats in Yunnan Province, China. Effective control strategies and measures should be taken to reduce the risk of E. bieneusi transmission between black goats, other animals, and humans.

Enterocytozoon Bieneusi Infects Children With Inflammatory Bowel Disease Undergoing Immunosuppressive Treatment

Objectives: Patients with inflammatory bowel disease (IBD) are susceptible to intestinal opportunistic infections due to both defective mucosal immunity and altered immune response resulting from immunosuppressive treatment. Microsporidia infecting the gastrointestinal tract and causing diarrhoea can potentially affect the course of IBD.

Methods: Stool samples (90 IBD children and 121 healthy age-matched controls) were screened for Encephalitozoon spp. and Enterocytozoon bieneusi by microscopy and polymerase chain reaction followed by sequencing.

Results:E. bieneusi genotype D was found in seven out of 90 (7.8%) IBD children. No children from the control group were infected, making the pathogen prevalence in the IBD group significant (P = 0.002). Furthermore, infection was confirmed only in patients receiving immunosuppressive treatment (P = 0.013).

Conclusions: Children with IBD are at risk of intestinal E. bieneusi infection, especially when receiving immunosuppressive treatment. Therefore, microsporidia should be considered as a significant infectious agent in this group of patients.

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

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

Survey on the Presence of Bacterial and Parasitic Zoonotic Agents in the Feces of Wild Birds

Wild avifauna may act as fecal source of bacterial and parasitic pathogens for other birds and mammals. Most of these pathogens have a relevant impact on human and livestock health which may cause severe disease and economic loss. In the present study, the fecal samples collected from 121 wild birds belonging to 15 species of the genera Anas, Tadorna, Fulica, Arddea, Larus, Falco, Athene, Accipiter, and Columba were submitted to bacteriological and molecular analyses to detect Brucella spp., Coxiella burnetii, Mycobacterium spp., Salmonella spp., Cryptosporidium spp., Giardia spp., and microsporidia. Four (3.3%) animals were positive for one pathogen: one Anas penelope for C. burnetii, one Larus michahellis for S. enterica serovar Coeln, and two Columba livia for Encephalitozoon hellem. Although the prevalence rates found in the present survey were quite low, the obtained results confirm that wild birds would be the a potential fecal source of bacterial and parasitic zoonotic pathogens which sometimes can also represent a severe threat for farm animals.

Molecular detection of Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi in school children at the Thai-Myanmar border

Few data are available on the genetic identity of enteric protists Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi in humans in Thailand. In this study, 254 stool samples were collected from primary school children from Ratchaburi Province at the Thai-Myanmar border and examined for Cryptosporidium spp., G. duodenalis, E. bieneusi and Cyclospora cayetanensis using PCR techniques. The genotype identity of the pathogens was determined by DNA sequence analysis of the PCR products. Cryptosporidium felis was found in 1 stool sample, G. duodenalis in 19 stool samples, and E. bieneusi in 4 stool samples. For G. duodenalis, sub-assemblage AII was the dominant genotype, but one infection with assemblage F was found. The E. bieneusi genotypes found included known genotypes D and J, and one novel genotype (HPTM1). Cyclospora cayetanensis was not detected in any samples. Results of the preliminary study indicate that children at the Thai-Myanmar border from Ratchaburi Province, Thailand are infected with diverse zoonotic genotypes of Cryptosporidium spp., G. duodenalis, and E. bieneusi.

Molecular detection and genotyping of Enterocytozoon bieneusi in pet dogs in Xinjiang, Northwestern China

Enterocytozoon bieneusi is an obligate intracellular parasitic fungi that infects a wide range of mammalian hosts. However, the literature is lacking information regarding the presence and diversity of E. bieneusi genotypes in domesticated dogs in Northwestern China. Fecal samples from 604 pet dogs were obtained in 5 cities (Urumqi, Korla, Hotan, Aksu, and Shihezi) in Xinjiang. Screening for E. bieneusi was performed, and isolates were genotyped via nested-PCR amplification of the internal transcribed spacer (ITS) of nuclear ribosomal DNA. The infection rate of E. bieneusi was 6.3% (38/604). The prevalence of E. bieneusi infections in adult animals (>1 year, 10.3%, 15/145) was higher than that in younger (≤1 year) dogs (5.0%, 23/459), which was statistically significant (p = 0.021). No significant difference was observed between the different collection sites or between sexes. Eight distinct genotypes were identified, including 5 known genotypes (PtEb IX, EbpC, D, CD9, and Type IV) and 3 novel genotypes (CD11, CD12, CD13). The most prevalent was genotype PtEb IX, being observed in 50.0% (19/38) of the samples, followed by EbpC (31.6%, 12/38), D (5.3%, 2/38), and the remaining genotypes (CD9, Type IV, CD11, CD12, and CD13) were observed in 1 sample (2.6%, 1/38) each. These findings suggest that genotypes PtEb IX and CD9 are canine host-adapted, and likely pose little risk of zoonotic transmission. Moreover, known zoonotic genotypes EbpC, D, and Type IV represent a public health concern and should undergo further molecular epidemiological investigation.

Microsporidiosis in Humans

Microsporidia are obligate intracellular pathogens identified ∼150 years ago as the cause of pébrine, an economically important infection in silkworms. There are about 220 genera and 1,700 species of microsporidia, which are classified based on their ultrastructural features, developmental cycle, host-parasite relationship, and molecular analysis. Phylogenetic analysis suggests that microsporidia are related to the fungi, being grouped with the Cryptomycota as a basal branch or sister group to the fungi. Microsporidia can be transmitted by food and water and are likely zoonotic, as they parasitize a wide range of invertebrate and vertebrate hosts. Infection in humans occurs in both immunocompetent and immunodeficient hosts, e.g., in patients with organ transplantation, patients with advanced human immunodeficiency virus (HIV) infection, and patients receiving immune modulatory therapy such as anti-tumor necrosis factor alpha antibody. Clusters of infections due to latent infection in transplanted organs have also been demonstrated. Gastrointestinal infection is the most common manifestation; however, microsporidia can infect virtually any organ system, and infection has resulted in keratitis, myositis, cholecystitis, sinusitis, and encephalitis. Both albendazole and fumagillin have efficacy for the treatment of various species of microsporidia; however, albendazole has limited efficacy for the treatment of Enterocytozoon bieneusi. In addition, immune restoration can lead to resolution of infection. While the prevalence rate of microsporidiosis in patients with AIDS has fallen in the United States, due to the widespread use of combination antiretroviral therapy (cART), infection continues to occur throughout the world and is still seen in the United States in the setting of cART if a low CD4 count persists.

FIRST REPORT OF ENTEROCYTOZOON BIENEUSI FROM AN AFRICAN LION (PANTHERA LEO) IN A ZOO IN THE REPUBLIC OF KOREA

Enterocytozoon bieneusi is the most common species of microsporidia that infects humans and animals worldwide. However, no information is available on E. bieneusi infection among zoo animals in the Republic of Korea (ROK). Here, we investigated the prevalence of E. bieneusi among animals kept in zoos and the zoonotic potential of the E. bieneusi identified. E. bieneusi was detected only in one African lion (Panthera leo) with diarrhea, using PCR and sequencing analysis of the internal transcribed spacer (ITS) of the rRNA gene. A phylogenetic analysis based on the ITS gene showed that the lion isolate was classified into a novel genotype KPL belonging to Group 2. The KPL genotype identified in this study differed from genotype I in 6 nucleotides and from genotype I-like in 3 nucleotides, respectively, indicating that Group 2 has the capacity to infect a wide range of hosts. This is the first report of the presence of E. bieneusi in an African lion housed in a zoo in the ROK. Further investigation is necessary to study E. bieneusi infection among zoo animals in various regions and to determine the transmission route, in order to control E. bieneusi infection.

The largest meta-analysis on the global prevalence of microsporidia in mammals, avian and water provides insights into the epidemic features of these ubiquitous pathogens

BACKGROUND

Microsporidia are obligate intracellular parasites that can infect nearly all invertebrates and vertebrates, posing a threat to public health and causing large economic losses to animal industries such as those of honeybees, silkworms and shrimp. However, the global epidemiology of these pathogens is far from illuminated.

METHODS

Publications on microsporidian infections were obtained from PubMed, Science Direct and Web of Science and filtered according to the Newcastle-Ottawa Quality Assessment Scale. Infection data about pathogens, hosts, geography and sampling dates were manually retrieved from the publications and screened for high quality. Prevalence rates and risk factors for different pathogens and hosts were analyzed by conducting a meta-analysis. The geographic distribution and seasonal prevalence of microsporidian infections were drawn and summarized according to sampling locations and date, respectively.

RESULTS

Altogether, 287 out of 4129 publications up to 31 January 2020 were obtained and met the requirements, from which 385 epidemiological data records were retrieved and effective. The overall prevalence rates in humans, pigs, dogs, cats, cattle, sheep, nonhuman primates and fowl were 10.2% [2429/30,354; 95% confidence interval (CI) 9.2-11.2%], 39.3% (2709/5105; 95% CI 28.5-50.1%), 8.8% (228/2890; 95% CI 5.1-10.1%), 8.1% (112/1226; 95% CI 5.5-10.8%), 16.6% (2216/12,175; 95% CI 13.5-19.8%), 24.9% (1142/5967; 95% CI 18.6-31.1%), 18.5% (1388/7009; 95% CI 13.1-23.8%) and 7.8% (725/9243; 95% CI 6.4-9.2%), respectively. The higher prevalence in pigs suggests that routine detection of microsporidia in animals should be given more attention, considering their potential roles in zoonotic disease. The highest rate was detected in water, 58.5% (869/1351; 95% CI 41.6-75.5%), indicating that water is an important source of infections. Univariate regression analysis showed that CD4+ T cell counts and the living environment are significant risk factors for humans and nonhuman primates, respectively. Geographically, microsporidia have been widely found in 92 countries, among which Northern Europe and South Africa have the highest prevalence. In terms of seasonality, the most prevalent taxa, Enterocytozoon bieneusi and Encephalitozoon, display different prevalence trends, but no significant difference between seasons was observed. In addition to having a high prevalence, microsporidia are extremely divergent because 728 genotypes have been identified in 7 species. Although less investigated, microsporidia coinfections are more common with human immunodeficiency virus and Cryptosporidium than with other pathogens.

CONCLUSIONS

This study provides the largest-scale meta-analysis to date on microsporidia prevalence in mammals, birds and water worldwide. The results suggest that microsporidia are highly divergent, widespread and prevalent in some animals and water and should be further investigated to better understand their epidemic features.

Enterocytozoon bieneusi of animals-With an 'Australian twist'

Enterocytozoon bieneusi is a microsporidian microorganism that causes intestinal disease in animals including humans. E. bieneusi is an obligate intracellular pathogen, typically causing severe or chronic diarrhoea, malabsorption and/or wasting. Currently, E. bieneusi is recognised as a fungus, although its exact classification remains contentious. The transmission of E. bieneusi can occur from person to person and/or animals to people. Transmission is usually via the faecal-oral route through E. bieneusi spore-contaminated water, environment or food, or direct contact with infected individuals. Enterocytozoon bieneusi genotypes are usually identified and classified by PCR-based sequencing of the internal transcribed spacer region (ITS) of nuclear ribosomal DNA. To date, ~600 distinct genotypes of E. bieneusi have been recorded in ~170 species of animals, including various orders of mammals and reptiles as well as insects in >40 countries. Moreover, E. bieneusi has also been found in recreational water, irrigation water, and treated raw- and waste-waters. Although many studies have been conducted on the epidemiology of E. bieneusi, prevalence surveys of animals and humans are scant in some countries, such as Australia, and transmission routes of individual genotypes and related risk factors are poorly understood. This article/chapter reviews aspects of the taxonomy, biology and epidemiology of E. bieneusi; the diagnosis, treatment and prevention of microsporidiosis; critically appraises the naming system for E. bieneusi genotypes as well as the phylogenetic relationships of these genotypes; provides new insights into the prevalence and genetic composition of E. bieneusi populations in animals in parts of Australia using molecular epidemiological tools; and proposes some areas for future research in the E. bieneusi/microsporidiosis field.

Characterizations of Enterocytozoon bieneusi at new genetic loci reveal a lack of strict host specificity among common genotypes and the existence of a canine-adapted Enterocytozoon species

Molecular characterizations of the microsporidian pathogen Enterocytozoon bieneusi at the ribosomal internal transcribed spacer (ITS) locus have identified nearly 500 genotypes in 11 phylogenetic groups with different host ranges. Among those, one unique group of genotypes, Group 11, is commonly found in dogs. Genetic characterizations of those and many divergent E. bieneusi genotypes at other genetic loci are thus far impossible. In this study, we sequenced 151 E. bieneusi isolates from several ITS genotype groups at the 16S rRNA locus and two new semi-conservative genetic markers (casein kinase 1 (ck1) and spore wall protein 1 (swp1)). Comparison of the near full (~1,200 bp) 16S rRNA sequences showed mostly two to three nucleotide substitutions between Group 1 and Group 2 genotypes, while Group 11 isolates differed from those by 26 (2.2%) nucleotides. Sequence analyses of the ck1 and swp1 loci confirmed the genetic uniqueness of Group 11 genotypes, which produced sequences very divergent from other groups. In contrast, genotypes in Groups 1 and 2 produced similar nucleotide sequences at these genetic loci, and there was discordant placement of ITS genotypes among loci in phylogenetic analyses of sequences. These results suggest that the canine-adapted Group 11 genotypes are genetically divergent from other genotype groups of E. bieneusi, possibly representing a different Enterocytozoon sp. They also indicate that there is no clear genetic differentiation of ITS Groups 1 and 2 at other genetic loci, supporting the conclusion on the lack of strict host specificity in both groups. Data and genetic markers from the study should facilitate population genetic characterizations of E. bieneusi isolates and improve our understanding of the zoonotic potential of E. bieneusi in domestic animals.

Genotyping and zoonotic potential of Enterocytozoon bieneusi in cattle farmed in Hainan Province, the southernmost region of China

Enterocytozoon bieneusi is an intestinal pathogen that infects a wide range of species, including humans. Cattle constitute an important host for E. bieneusi; however, there is a scarcity of information on the prevalence and genotyping of E. bieneusi in cattle in the Hainan Province of China. In this study, PCR analysis of 314 fecal samples from cattle in six cities of Hainan was performed for genotype identification. The average prevalence of E. bieneusi in these animals was 9.9% (31/314), and ranged from 0.0% (0/12) to 20.5% (8/39). Five known genotypes – EbpC (n = 14), BEB4 (n = 12), J (n = 2), I (n = 1), and CHG5 (n = 1) – and a novel genotype: HNC-I (n = 1) – were identified. Genotypes EbpC and HNC-I were placed in zoonotic Group 1, and the remaining four genotypes (BEB4, J, I, and CHG5) were placed in Group 2. Since 93.5% of the genotypes found in the cattle (29/31) (EbpC, BEB4, J, and I) have previously been found in humans, these genotypes are probably involved in the transmission of microsporidiosis to humans.

Host-adaptation of the rare Enterocytozoon bieneusi genotype CHN4 in Myocastor coypus (Rodentia: Echimyidae) in China

BACKGROUND

Enterocytozoon bieneusi is a zoonotic gastrointestinal pathogen and can infect both humans and animals. The coypu (Myocastor coypus) is a semi-aquatic rodent, in which few E. bieneusi infections have been reported and the distribution of genotypes and zoonotic potential remains unknown.

METHODS

A total of 308 fresh fecal samples were collected from seven coypu farms in China to determine the infection rate and the distribution of genotypes of E. bieneusi from coypus using nested-PCR amplification of the internal transcribed spacer (ITS) region of the ribosomal RNA (rRNA) gene.

RESULTS

Enterocytozoon bieneusi was detected with an infection rate of 41.2% (n = 127). Four genotypes were identified, including three known genotypes (CHN4 (n = 111), EbpC (n = 8) and EbpA (n = 7)) and a novel genotype named CNCP1 (n = 1).

CONCLUSIONS

The rare genotype CHN4 was the most common genotype in the present study, and the transmission dynamics of E. bieneusi in coypus were different from other rodents. To the best of our knowledge, this is the first report of E. bieneusi infections in coypus in China. Our study reveals that E. bieneusi in coypus may be a potential infection source to humans.

Encephalitozoon cuniculi Genotype II Concentrates in Inflammation Foci

Background

Microsporidia of the genus Encephalitozoon are generally connected with severe infections with lethal outcome in immunodeficient hosts. In immunocompetent hosts, microsporidiosis typically establishes a balanced host–parasite relationship that produces minimal clinically overt disease. Although the alimentary tract represents one of the main primary target tissues, the mechanisms of reaching other tissues during systemic microsporidian infections remain unclear.

Methods

In the present study, we tested the relation between inflammation induction in immunocompetent and immunodeficient mice and the presence of spores of E. cuniculi genotype II in selected organs and in fecal specimens by using molecular and histology methods.

Results

We reported the positive connection between inflammation induction and the significant increase of E. cuniculi genotype II occurrence in inflammation foci in both immunocompetent BALB/c and immunodeficient severe combined immunodeficient (SCID) mice in the acute phase of infection and the re-activation of latent microsporidial infection following inflammation induction in immunocompetent mice.

Conclusion

The results imply possible involvement of immune cells serving as vehicles transporting E. cuniculi genotype II purposefully across the whole host body towards inflammation. With increasing number of records of infections, it is necessary to reconsider microsporidia as agents responsible for various pathologies. The elucidation of possible connection with pro-inflammatory immune responses represents an important challenge with consequences for human health and development of therapeutic strategies.

Population genetic analysis suggests genetic recombination is responsible for increased zoonotic potential of Enterocytozoon bieneusi from ruminants in China

Enterocytozoon bieneusi is a zoonotic pathogen with worldwide distribution. Among the 11 established groups of E. bieneusi genotypes based on phylogenetic analysis of the ribosomal internal transcribed spacer (ITS), the human-infective potential and population genetics of the Group 1 genotypes from diverse hosts are well characterized. In contrast, Group 2 genotypes from ruminants have unclear population genetics, leading to poor understanding of their host range and zoonotic potential. In this study, we sequence-characterized 121 Group 2 isolates from dairy cattle, beef cattle, yaks, Tibetan sheep, golden takins, and deer from China at five genetic loci (ITS, MS1, MS3, MS4 and MS7), comparing with data from 113 Group 1 isolates from nonhuman primates. Except for MS7, most of the genetic loci produced efficient PCR amplification and high nucleotide identity between Groups 1 and 2 of E. bieneusi genotypes. In population genetic analyses of the sequence data, a strong linkage disequilibrium was observed among these genetic loci in the overall Group 2 population. The individual ITS genotypes (I, J and BEB4) within Group 2, however, had reduced linkage disequilibrium and increased genetic exchanges among isolates. There was only partial genetic differentiation between Group 1 and Group 2 genotypes, with some occurrence of genetic recombination between them. Genetic recombination was especially common between genotypes I and J within Group 2. The data presented indicate a high genetic identity between Group 1 and Group 2 genotypes of E. bieneusi, which could be responsible for the broad host range and high zoonotic potential of Group 2 genotypes in China. As there is no effective treatment against E. bieneusi, the One Health approach should be used in the control and prevention of zoonotic transmission of the pathogen.

Molecular detection of Cryptosporidium spp. and Enterocytozoon bieneusi in Longjiang Wagyu cattle in Northeastern China

Cryptosporidium spp. and Enterocytozoon bieneusi are two important zoonotic pathogens that can cause diarrhea and other gastrointestinal illnesses in humans and animals. However, the prevalence and genotype of the parasites in Longjiang Wagyu cattle in Heilongjiang Province, Northeast China have not been reported. In the present study, a total of 423 fecal samples of Longjiang Wagyu cattle collected from different farms in Heilongjiang Province, Northeast China, were examined for Cryptosporidium spp. and E. bieneusi using nested PCR. The overall infection rates for Cryptosporidium spp. and E. bieneusi were 6.38% (n = 27) and 7.09% (n = 30), respectively. The prevalence in different age groups ranged from 3.80% (95% confidence interval (CI) 1.01-6.59) to 8.36% (95% CI 4.83-11.90) for Cryptosporidium spp. and 5.97% (95% CI 2.52-9.43) to 7.94% (95% CI 4.49-11.40) for E. bieneusi. By analyzing the DNA sequences of the small subunit (SSU) rRNA gene, two Cryptosporidium species were detected in this study, namely C. parvum (n = 25) and C. ryanae (n = 2). The IIdA20G1 subtype was further identified by using the 60-kDa glycoprotein (gp60) gene of C. parvum. E. bieneusi was identified using three known sequences through the analysis of internal transcribed spacer (ITS) sequences: J (n = 23), I (n = 5), and BEB4 (n = 2), and all belonged to group 2. The results indicated that some of the Cryptosporidium species and E. bieneusi genotypes identified in Longjiang Wagyu cattle in the study areas might have zoonotic potential.

Enterocytozoon bieneusi in raw milk of cattle, sheep and water buffalo in Turkey: Genotype distributions and zoonotic concerns

Raw milk is a continued threat to public health due to possible contamination with zoonotic pathogens. Enterocytozoon bieneusi is one of the most prevalent pathogenic fungi in a wide range of vertebrate hosts, causing diarrheal disease. Although there has been some evidence, the role and potential risk of raw milk of dairy animals in the transmission dynamics of E. bieneusi is not clear. Therefore, we aimed to determine the occurrence and genotypes of E. bieneusi in raw milk of dairy animals in several farms of the Central Anatolia Region. We also investigated if there is a relation between the presence of E. bieneusi and mastitis. Genomic DNAs from a total of 450 raw milk including 200, 200 and 50 samples from cattle, sheep and water buffalo respectively were analyzed using nested PCR, targeting the internal transcribed spacer of E. bieneusi. Totally milk samples of 9 (4.5%) dairy cattle, 36 (18.0%) sheep, and 1 (2.0%) water buffalo were PCR-positive. A significant relationship was determined between mastitis and the presence of E. bieneusi. Sequence analysis revealed the presence of eight genotypes: two known (ERUSS1, BEB6) and six novel genotypes (named as TREb1 to TREb6). The genotype ERUSS1 and BEB6 were the most common genotypes, found in all cattle and sheep farms. Phylogenetic analysis clustered all the identified genotypes in Group 2. This study provides novel findings that contribute to the transmission dynamics and molecular epidemiology of E. bieneusi. Our study also highlighted the potential risk of raw milk for public health with respect to microsporidia infections.

Molecular detection and genotyping of microsporidia species in chickens in Turkey

Microsporidia are obligate intracellular pathogens that infect various hosts including invertebrates and vertebrates. Despite the importance, knowledge on the prevalence and molecular characteristics of microsporidia in chickens is limited, and no data are available for Turkey. A total of 300 fecal samples from chickens in the Central Anatolia Region of Turkey were analyzed by using a nested polymerase chain reaction assay targeting the rRNA internal transcribed spacer (ITS) region for the common microsporidia species. Corresponding PCR amplicons from the positive samples were sequenced for genotyping. Enterocytozoon bieneusi was identified in 22 (7.3 %) samples, whereas Encephalitozoon spp. was not detected. The prevalence of E. bieneusi was 63.6 % in Kayseri and 36.4 % in Nevsehir provinces, and 8.8 % in soft fecal samples and 9.7 % in diarrhoeic samples. No infections were found in Kirsehir Province. Significant differences were found for the distribution of E. bieneusi among provinces and fecal conditions. Infections were found only in free-range chickens. As a result of ITS region sequencing, two genotypes were characterized. The novel genotype ERUNT1 (n = 21), belonging to zoonotic group 1, was the most common genotype throughout the study area. The other known genotype, ERUSS1 (n = 1), had a restricted distribution and was previously detected in cattle and sheep in the same region. Our study provides the first data on microsporidia species from chickens in Turkey. None of these genotypes have been reported in humans; thus, the risk potential for public health is limited but needs further investigation.

A massive systematic infection of Encephalitozoon cuniculi genotype III in mice does not cause clinical signs

Encephalitozoon cuniculi genotype III disseminated intensively into most of the organs in all strains of mice, followed by a chronic infection with massive microsporidia persistence in immunodeficient mice and a partial decrease in C57Bl/6 mice. Treatment with 0.2 mg Albendazole/mouse/day temporarily reduces the number of affected organs in immunocompetent C57Bl/6 mice, but not in CD4^-/- and CD8^-/- mice. The application of medication temporarily decreased the spore burden at least by one order of magnitude in all groups. These results demonstrate that the E. cuniculi genotype III infection had a progressive course and surprisingly, Albendazole treatment had only a minimal effect. The E. cuniculi genotype III spore burden in individual organs reached up to 10⁸ or 10⁹ in immunocompetent or immunodeficient mice, respectively; however, these mice did not demonstrate any obvious clinical signs of microsporidiosis, and the immunodeficient mice survived longer. Our findings clearly show that the survival of mice does not correspond to spore burden, which provides new insight into latent microsporidiosis from an epidemiological point of view.

Intestinal microsporidia infection among cat owners and non-pet owners in Iran: a case-control study

Microsporidia is a group of spore-forming microorganisms with zoonotic potential. This study aimed to compare intestinal microsporidia infections in cat owners and non-pet owners. In total, 210 fecal samples were collected from indoor cats, cat owners, and non-pet owners. DNA extraction was performed and the small subunit ribosomal RNA (SSU rRNA) gene was amplified. To characterize the genotypes, the internal transcribed spacer (ITS) fragment was amplified and sequenced. The phylogenetic trees were drawn to evaluate the relationship among Enterocytozoon bieneusi isolates. Two (2.9%) and one (1.4%) fecal samples from cat owners and one (1.4%) and two (2.9%) fecal samples from non-pet owners were positive for E. bieneusi and Encephalitozoon intestinalis, respectively. E. bieneusi was detected in two cat samples (2.9%). Same infection was not seen between infected cats and their owners. There was no significant difference between the prevalence rate of microsporidia among the cat owners and non-pet owners. Indeed, the genotypes L and type IV were seen in cats, while the genotype D was only detected in human. In this study, E. bieneusi and E. intestinalis were more prevalent among the cat owners and non-pet owners, respectively. Indeed, the higher prevalence of E. bieneusi in cats and their owners might be resulted from the worldwide distribution of this species.

Molecular Diversity of Giardia duodenalis, Cryptosporidium spp. and Blastocystis sp. in Asymptomatic School Children in Leganés, Madrid (Spain)

Enteric parasites including Giardia duodenalis, Cryptosporidium spp., and to a lesser extent, Blastocystis sp. and Enterocytozoon bieneusi, are major worldwide contributors to diarrhoeal disease. Assessing their molecular frequency and diversity is important to ascertain the sources of infection, transmission dynamics, and zoonotic potential. Little molecular information is available on the genotypes of these pathogens circulating in apparently healthy children. Here, we show that asymptomatic carriage of G. duodenalis (17.4%, 95% CI: 15.5‒19.4%), Blastocystis sp. (13.0%, 95% CI: 11.4‒14.8%), and Cryptosporidium spp. (0.9%, 95% CI: 0.5‒1.5%) is common in children (1‒16 years; n = 1512) from Madrid, Spain. Our genotyping data indicate that; (i) the observed frequency and diversity of parasite genetic variants are very similar to those previously identified in Spanish clinical samples, so that the genotype alone does not predict the clinical outcome of the infection, (ii) anthroponotic transmission accounts for a large proportion of the detected cases, highlighting that good personal hygiene practices are important to minimizing the risk of infection, (iii) Blastocystis ST4 may represent a subtype of the parasite with higher pathogenic potential, and (iv) Enterocytozoon bieneusi does not represent a public health concern in healthy children.

Molecular detection of Enterocytozoon bieneusi in farm-raised pigs in Hainan Province, China: infection rates, genotype distributions, and zoonotic potential

Enterocytozoon bieneusi is a zoonotic fungal pathogen with a high degree of host diversity that can parasitize many animals, including humans. Pigs may play an important role in the epidemiology of E. bieneusi as reservoir hosts. Nevertheless, the genotypes of E. bieneusi in pigs in China remain poorly understood. The aim of this study was to determine the prevalence of E. bieneusi infection amongst pigs raised on farms from four cities of Hainan Province, using nested polymerase chain reaction (PCR) of the partial small subunit of the ribosomal RNA gene, and to identify genotypes of E. bieneusi isolates based on sequence analysis of the ribosomal internal transcribed spacer (ITS) region. Among 188 stool samples, E. bieneusi was detected in 46.8% (88/188). Eight genotypes including four known (EbpA, CS-4, MJ14, and CHG19) and four novel (HNP-I – HNP-IV) genotypes were identified. Using phylogenetic analysis, genotypes EbpA, CS4, CHG19, HNP-III, and HNP-IV were clustered into zoonotic Group 1, while the remaining three genotypes (MJ14, HNP-I, and HNP-II) clustered into Group 10. The high prevalence of zoonotic genotypes of E. bieneusi among pigs suggests that pig farming is a potential source of human infection. Additionally, this is the first identification of genotypes in Group 10 in pigs indicating unique epidemic features of E. bieneusi in pigs in Hainan Province, the southernmost part of China.

Molecular characterization and distribution of Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi from yaks in Tibet, China

BACKGROUND

With worldwide distribution and importance for veterinary medicine, Cryptosporidium spp., Giardia duodenalis, and Enterocytozoon bieneusi have been found in a wide variety of vertebrate hosts. At present, few available molecular data can be used to understand the features of genetic diversity of these pathogens in areas without or less intensive farming. Dominated by grazing, Tibet is a separate geographic unit in China and yaks are in frequent contact with local herdsmen and necessary for their daily life. Therefore, to investigate the distribution of these pathogens in yaks of Tibet, 577 fecal specimens were screened using nested PCR for the presence and genotypes of the three intestinal pathogens.

RESULTS

The overall prevalence of Cryptosporidium spp., G. duodenalis, and E. bieneusi were 1.4% (8/577), 1.7% (10/577), and 5.0% (29/577), respectively. Cryptosporidium andersoni (n = 7) and Cryptosporidium bovis (n = 1) were detected by sequence analysis of the SSU rRNA gene. Genotyping at the SSU rRNA and triosephosphate isomerase genes suggested that all G. duodenalis positive specimens belonged to assemblage E. Sequence analysis of the internal transcribed spacer gene identified six known E. bieneusi genotypes: BEB4 (n = 11), I (n = 6), D (n = 5), J (n = 2), CHC8 (n = 1), and BEB6 (n = 1). One subtype (A5,A4,A2,A1) for C. andersoni and three multilocus genotypes for E. bieneusi were identified by multilocus sequence typing.

CONCLUSIONS

We report for the first time the status of three enteric pathogens infection simultaneously for grazing yaks in Tibet. Yaks in our study are likely to impose a low zoonotic risk for humans. The molecular epidemiology data add to our knowledge of the characteristics of distribution and transmission for these pathogens in Tibet and their zoonotic potential and public health significance.