Brown rats (Rattus norvegicus) as potential reservoirs of Enterocytozoon bieneusi in Heilongjiang Province, China: high prevalence, genetic heterogeneity, and potential risk for zoonotic transmission

Introduction

Enterocytozoon bieneusi, an obligatory intracellular fungus, is prevalent among animals and humans. Due to their close interaction with humans and their extensive regional distribution, brown rats (Rattus norvegicus) are important pathogen reservoirs. To assess the zoonotic transmission potential of E. bieneusi, a molecular investigation was conducted on 817 R. norvegicus from four cities in Heilongjiang Province, China.

Methods

A total of 817 R. norvegicus were collected from four cities in Heilongjiang Province, China. The genotyping of E. bieneusi was conducted through PCR amplification of the small subunit ribosomal RNA (SSU rRNA)'s internal transcribed spacer (ITS) segments. Phylogenetic and similarity analyses were used to examine zoonotic potential and genetic characteristics of the E. bieneusi-positive specimens.

Results

Among the 817 R. norvegicus, the total infection rate was 33.3% (272/817). Seventy-five genotypes were identified, including 14 known genotypes D (n = 167), A (n = 15), HLJ-CP1 (n = 12), WR8 (n = 6), EbpC (n = 2), BEB6 (n = 1), CS-4 (n = 1), CHPM1 (n = 1), Henan-II (n = 1), HNH-22 (n = 1), HNH-25 (n = 1), I (n = 1), JLD-XI (n = 1), SDD5 (n = 1), and 61 novel genotypes designated as SHWR1 (n = 10), SYSWR1 (n = 2), and SHWR2 to SHWR17, SYSWR2 to SYSWR36 and QTHWR1 to QTHWR8 (n = 1, each). Moreover, 10 samples exhibited mixed genotype infections, including D + A (n = 3), D + EbpC (n = 1), D + HLJ-CP1 (n = 1), D + SHWR1 (n = 1), D + SHWR16 (n = 1), D + SHWR17 (n = 1), SDD5 + WR8 (n = 1), and CS-4 + SYSWR36 (n = 1). Phylogenetic analysis grouped the genotypes into three main groups: group 1 (n = 67), group 2 (n = 5), and group 9 (n = 3).

Discussion

The high prevalence and genetic diversity of E. bieneusi in Heilongjiang Province's R. norvegicus imply that these animals spread the pathogen. The R. norvegicus that E. bieneusi carries can spread zoonotic disease, making it a serious hazard to the local human population. Therefore, it is imperative to raise awareness about the dangers posed by R. norvegicus and implement measures to reduce their population to prevent environmental contamination.

Prevalence and molecular characterization of Enterocytozoon bieneusi and a new Enterocytozoon sp. in pet hairless guinea pigs (Cavia porcellus) from China

Enterocytozoon bieneusi, the most common microsporidian species, has been detected in humans and a variety of animals worldwide. However, limited information is available on the prevalence and molecular characterization of this parasite in guinea pigs. In this study, we conducted the first investigation of E. bieneusi infection in hairless guinea pigs recently introduced into China as new exotic pets. A total of 324 fecal samples were collected from hairless guinea pigs from a pet market and four breeding facilities in China. Sequence alignment of the internal transcribed spacer (ITS) revealed an infection rate of 14.2% (46/324) and two known ITS genotypes, S7 and PGP. Genotype S7 was the dominant genotype in these animals (42/46, 91.3%). Due to significant ITS sequence divergence, four and two PGP isolates from hairless and regular guinea pigs, respectively were further identified by PCR and phylogenetic analysis based on the small subunit (SSU) rRNA gene, as well as phylogenetic analysis of the ITS locus using E. hepatopenaei and two related genera Enterospora and Nucleospora as the outgroup. Three out of the six PGP isolates were successfully sequenced and generated the same sequences. Phylogenetic analysis of SSU rRNA and ITS loci revealed that PGP isolates formed a separate clade that was distinct and far away from E. bieneusi, suggesting that they represent a new species of Enterocytozoon. These findings indicate the dominance of zoonotic E. bieneusi genotype S7 in hairless guinea pigs and the existence of a cryptic Enterocytozoon species in guinea pigs.

First detection and genotyping of Enterocytozoon bieneusi in pet golden hamsters (Mesocricetus auratus) and Siberian hamsters (Phodopus sungorus) in China

Enterocytozoon bieneusi, a common opportunistic pathogen, has been detected in humans and a wide range of animals worldwide. However, no information on the prevalence and molecular characterization of E. bieneusi in hamsters is available worldwide. In this study, fecal specimens were collected from 175 golden hamsters and 175 Siberian hamsters purchased from pet shops in three provinces of China. The average infection rate of E. bieneusi was 12.0% (42/350), with 14.9% (26/175) in pet golden hamsters and 9.1% (16/175) in pet Siberian hamsters. Four genotypes were identified in pet golden hamsters, including three known genotypes (D, Henan-II, and SHW5) and one novel genotype (named Ebph1). Five genotypes were found in pet Siberian hamsters, including one known genotype (D) and four novel genotypes (named Ebph2 to Ebph5). Genotypes D and Ebph2 were the dominant genotype in pet golden hamsters (23/26, 88.5%) and Siberian hamsters (9/16, 56.3%), respectively. Phylogenetic analysis showed that the E. bieneusi isolates clustered into two groups: Group 1 (D, Henan-II, SHW5, and Ebph1) and Group 3 (Ebph2 to Ebph5). To the best of our knowledge, this is the first report of E. bieneusi infection in golden hamsters and Siberian hamsters worldwide. The identification of four genotypes belonging to Group 1 of high zoonotic potential suggests that pet hamsters especially golden hamsters can be potential sources of human microsporidiosis.

A Systematic Review and Meta-analysis on the Global Molecular Epidemiology of Microsporidia Infection Among Rodents: A Serious Threat to Public Health

BACKGROUND

Microsporidiosis as a zoonotic disease has caused serious health problems in high-risk groups, including immunosuppressed individuals. Among the potential animal reservoirs of microsporidia, rodents play a key role due to close-contact with humans and their dispersion in different environments. Therefore, this systematic review and meta-analysis aimed to assess the global status and genetic diversity of microsporidia infection in different rodents.

METHODS

The standard protocol of preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed. Scopus, PubMed, Web of Science, and Google Scholar were searched from 1 January 2000 to 15 April 2021. All peer-reviewed original research articles describing the molecular prevalence of microsporidia infection in rodents were included. Inclusion and exclusion criteria were applied. The point estimates and 95% confidence intervals were calculated using a random-effects model. The variance between studies (heterogeneity) were quantified by I² index.

RESULTS

Of 1695 retrieved studies, 22 articles (including 34 datasets) were included for final meta-analysis. The pooled global molecular prevalence (95% CI) of microsporidia infection in rodents was 14.2% (95% CI 10.9-18.3%). The highest prevalence of microsporidia was found in Apodemus spp. 27.3% (95% CI 15-44.5%). Enterocytozoon bieneusi was the most common pathogen (26/34; 76.47% studies) according to PCR-based methods, and the genotype D as the highest reported genotype (15 studies).

CONCLUSIONS

The findings of the study showed a relatively high prevalence of microsporidia infection in rodents as a potential animal reservoir for infecting human. Given the relatively high incidence of microsporidiosis, designing strategies for control, and prevention of microsporidia infection in rodents should be recommended.

First detection and genotyping of Enterocytozoon bieneusi in pet fancy rats (Rattus norvegicus) and guinea pigs (Cavia porcellus) in China

Enterocytozoon bieneusi, an obligate intracellular microsporidian parasite, can infect humans and a wide variety of animals worldwide. However, information on the prevalence and molecular characterization of E. bieneusi in pet rats and guinea pigs is lacking. In this study, 325 fecal samples were collected from 152 pet fancy rats and 173 pet guinea pigs purchased from pet shops in Henan and Shandong provinces. The prevalence of E. bieneusi was 11.2% (17/152) in pet fancy rats and 20.2% (35/173) in pet guinea pigs. Genotypes D (n = 12), Peru11 (n = 3), S7 (n = 1) and SCC-2 (n = 1) were identified in pet fancy rats, and genotype S7 (n = 30) and a novel genotype PGP (n = 5) were identified in pet guinea pigs. The ITS sequence and its phylogenetic analysis showed that the novel genotype PGP was distinctly different; it exhibited less than 50% similarity to the reference sequences, and did not cluster with any of the known E. bieneusi genotype groups, forming a unique branch between groups 6 and 7. These data suggest that this is a new E. bieneusi genotype group. This is the first report of E. bieneusi infection in pet fancy rats and pet guinea pigs worldwide. The identification of zoonotic genotypes D, Peru11, and S7 suggests that pet fancy rats and guinea pigs can be potential sources of human microsporidiosis.

The First Report and Molecular Analysis of Enterocytozoon bieneusi from Raccoon (Procyon lotor) in North of Iran

Microsporidia are known opportunistic microorganisms and usually transmitted via the fecal-oral route. However, there is no information about human-infecting microsporidia in wildlife in Iran. This study aimed to investigate and analyze human-infecting microsporidia isolated from raccoons in north of Iran. Totally, 30 fecal samples were collected; then, DNA extraction was performed and specific fragments of the SSU rRNA gene of Enterocytozoon bieneusi and Encephalitozoon species were amplified. After amplification and sequencing the ITS, the results were compared to the GenBank database. Phylogenetic trees and network analysis were employed to explore probable relationships. E. bieneusi was the only detected microsporidia among samples. Genotyping showed the genotypes D, E, and RA in 15/18 (83.33%), 1/18 (5.55%), and 2/18 (11.11%) of samples, respectively. Novel genotypes RA1 and RA2 grouped together and apart from other genotypes. E. bieneusi genotypes D and E clustered with the genotypes previously reported from animals, humans, and environmental samples. Network analysis revealed six distinct sequence types among raccoon's isolates. This study demonstrated that E. bieneusi genotype D was the most prevalent microsporidia among raccoons. It seems that wildlife may play a role in dispersion of microsporidia spores.

First insight into Encephalitozoon cuniculi infection in laboratory and pet rabbits in Iran

Encephalitozoon cuniculi infects a wide variety of domestic and wild mammalian species including humans. Although the infection status has been studied in laboratory and pet rabbits worldwide, there is shortage of information regarding the disease in Iran. In the present study, the occurrence of infection in brains of 117 asymptomatic rabbits from six breeding and experimental units with highest population of rabbit colonies in the country (n = 60) as well as pet rabbits of pet stores in two cities (n = 57) were examined by nested-PCR. Histological sections of brains and kidneys were also studied by light microscopy. PCR results revealed that 3.3% of laboratory rabbits (2/60) and 59.6% of pet rabbits (34/57) harboured E. cuniculi in their brains. Histopathology on the other hand showed spores of the parasite in kidney and brain of one and kidney of another pet rabbit. As encephalitozoonosis may interfere with results of experiments performed on laboratory rabbits, routine screenings for identification and culling of infected animals is recommended. Furthermore, infected companion rabbits can transmit E. cuniculi to people in close contact with them, therefore, improving public knowledge of this zoonotic infection is suggested.