Encephalitozoon infections in Rodentia and Soricomorpha in Japan

Detection of Blastocystis spp., Cryptosporidium spp. and Encephalitozoon spp. among wild animals from Eastern Slovakia

The aim of this study was to draw attention to the risk of transmission of Encephalitozoon, Cryptosporidium and Blastocystis infection due to high animal migration and to point out that even wild animals can be a source of many zoonotic diseases. Encephalitozoon cuniculi, Cryptosporidium spp. and Blastocystis spp. are frequent microscopic organisms that parasitise humans, domestic and wild animals. Two hundred and fifty-five faecal specimens were collected from wild boars, badgers, wolves, bears, foxes and deer from 15 locations in Slovakia. Sequencing of positive PCR products and subsequent sequence comparison with GenBank sequences identified Blastocystis spp. in five wild boars. The ST 5 (n = 4) and ST 10 (n = 1) subtypes were determined by genotyping. We identified Encephalitozoon cuniculi in five wild boars, and genotype II (n = 5) was determined on the basis of ITS repeat sequences. Cryptosporidium scrofarum was sequenced in wolves (n = 4) and wild boars (n = 1), while Cryptosporidium suis only in wild boars (n = 2). None of the wild boars had a mixed infection.

Feline intralenticular Encephalitozoon cuniculi: three cases from California

Case series summary

Three domestic shorthair cats from California presented to veterinary ophthalmologists with immature cataracts. Other presenting clinical signs included corneal edema, anisocoria, anterior uveitis, elevated intraocular pressure, blepharospasm and/or lethargy. All patients were immunocompromised due to concurrent diseases and/or immunomodulatory drugs. Diagnostics included serial comprehensive ophthalmic examinations with tonometry, ocular ultrasound, electroretinogram and testing for other causes of feline uveitis. Testing for Encephalitozoon cuniculi included serology, histopathology and/or PCR of aqueous humor, lens material or paraffin-embedded whole eye. Treatments included antiparasitic medication, anti-inflammatory medication and supportive care in all three cases. Surgical treatment included enucleation (one case), bilateral phacoemulsification and unilateral intraocular lens placement (one case) and bilateral phacoemulsification with bilateral endolaser ciliary body ablation and bilateral intraocular lens implantation (one case). Both cats for which serologic testing for E cuniculi was performed were positive (1:64-1:4096). In all cats, diagnosis of intraocular E cuniculi was based on at least one of the following: lens histopathology or PCR of aqueous humor, lens material or paraffin-embedded ocular tissue. The clinical visual outcome was best in the patient undergoing phacoemulsification at the earliest stage of the cataract.

Relevance and novel information

Encephalitozoon cuniculi should be considered as a differential cause of cataracts and uveitis in cats in California, the rest of the USA and likely worldwide.

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.

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 course of infection of Encephalitozoon cuniculi genotype I in mice possess combination of features reported in genotypes II and III

Out of three genotypes of Encephalitozoon cuniculi (I-III) available for experimental studies, E. cuniculi genotype I remains the less characterized. This study describes for the first time individual phases of microsporidiosis caused by E. cuniculi genotype I and efficacy of albendazole treatment in immunocompetent BALB/c and C57Bl/6 mice and immunodeficient SCID, CD4^-/- and CD8^-/- mice using molecular detection and quantification methods. We demonstrate asymptomatic infection despite an intense dissemination of microsporidia into most organs within the first weeks post infection, followed by a chronic infection characterized by significant microsporidia persistence in immunocompetent, CD4^-/- and CD8^-/- mice and a lethal outcome for SCID mice. Albendazole application led to loss E. cuniculi genotype I infection in immunocompetent mouse strains, decreased spore burden by half in CD4^-/- and CD8^-/- mice, and prolongation of survival of SCID mice. These results showed Encephalitozoon cuniculi genotype I infection extend and albendazole sensitivity was comparable to E. cuniculi genotype II, but the infection onset speed and mortality rate was similar to E. cuniculi genotype III. These imply that differences in the course of infection and the response to treatment depend not only on immunological status of the host, but also on the genotype causing the infection.

Zoonotic Microsporidia in Wild Lagomorphs in Southern Spain

Microsporidia are obligate intracellular protist-like fungal pathogens that infect a broad range of animal species, including humans. This study aimed to assess the presence of zoonotic microsporidia (Enterocytozoon bieneusi, Encephalitozoon intestinalis, Encephalitozoon hellem, and Encephalitozoon cuniculi) in organ meats of European wild rabbit (Oryctolagus cuniculus) and Iberian hare (Lepus granatensis) consumed by humans in Spain. Between July 2015 and December 2018, kidney samples from 383 wild rabbits and kidney and brain tissues from 79 Iberian hares in southern Spain were tested by species-specific PCR for the detection of microsporidia DNA. Enterocytozoon bieneusi infection was confirmed in three wild rabbits (0.8%; 95% CI: 0.0-1.7%) but not in hares (0.0%; 95% CI: 0.0-4.6%), whereas E. intestinalis DNA was found in one wild rabbit (0.3%; 95% CI: 0.0-0.8%) and three Iberian hares (3.8%; 95% CI: 0.0-8.0%). Neither E. hellem nor E. cuniculi infection were detected in the 462 (0.0%; 95% CI: 0.0-0.8%) lagomorphs analyzed. The absence of E. hellem and E. cuniculi infection suggests a low risk of zoonotic foodborne transmission from these wild lagomorph species in southern Spain. To the authors' knowledge, this is the first report of E. intestinalis infection in wild rabbits and Iberian hares. The presence of E. bieneusi and E. intestinalis in organ meats from wild lagomorphs can be of public health concern. Additional studies are required to determine the real prevalence of these parasites in European wild rabbit and Iberian hare.

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.

The opportunistic pathogen Encephalitozoon cuniculi in wild living Murinae and Arvicolinae in Central Europe

Encephalitozoon spp. is an obligate intracellular microsporidian parasite that infects a wide range of mammalian hosts, including humans. This study was conducted to determine the prevalence of Encephalitozoon spp. in wild living rodents from Poland, the Czech Republic and Slovakia. Faecal and spleen samples were collected from individuals of Apodemus agrarius, Apodemus flavicollis, Apodemus sylvaticus, and Myodes glareolus (n = 465) and used for DNA extraction. PCR, targeting the ITS region of the rRNA gene was performed. The overall prevalence of microsporidia was 15.1%. The occurrence of Encephalitozoon cuniculi in the abovementioned host species of rodents has been presented for the first time, with the highest infection rate recorded for A. flavicollis. Sequence analysis showed that the most frequent species was E. cuniculi genotype II (92.5%). E. cuniculi genotypes I (1.5%) and III (6.0%) were also identified.

Serological survey of Encephalitozoon cuniculi infection in cats in Japan

Antibodies to Encephalitozoon cuniculi (E. cuniculi) were examined by enzyme-linked immunosorbent assay using E. cuniculi PTP2 recombinant protein from serum samples that had been collected from a total of 295 cats in Japan. Of these samples, 6.1% (18/295) had antibodies against E. cuniculi, which included 6.3% (6/96) of the male cats and 6.0% (12/199) of the female cats. The incidence was slightly higher in feral cats (8.3%, 11/132) compared to domesticated cats (4.3%, 7/163). This suggests the possibility that the cats of our country have become a reservoir of E. cuniculi. This study is the first to demonstrate the prevalence of E. cuniculi infection in cats in Japan.

More than a rabbit's tale - Encephalitozoon spp. in wild mammals and birds

Within the microsporidian genus Encephalitozoon, three species, Encephalitozoon cuniculi, Encephalitozoon hellem and Encephalitozoon intestinalis have been described. Several orders of the Class Aves (Passeriformes, Psittaciformes, Apodiformes, Ciconiiformis, Gruiformes, Columbiformes, Suliformes, Podicipediformes, Anseriformes, Struthioniformes, Falconiformes) and of the Class Mammalia (Rodentia, Lagomorpha, Primates, Artyodactyla, Soricomorpha, Chiroptera, Carnivora) can become infected. Especially E. cuniculi has a very broad host range while E. hellem is mainly distributed amongst birds. E. intestinalis has so far been detected only sporadically in wild animals. Although genotyping allows the identification of strains with a certain host preference, recent studies have demonstrated that they have no strict host specificity. Accordingly, humans can become infected with any of the four strains of E. cuniculi as well as with E. hellem or E. intestinalis, the latter being the most common. Especially, but not exclusively, immunocompromised people are at risk. Environmental contamination with as well as direct transmission of Encephalitozoon is therefore highly relevant for public health. Moreover, endangered species might be threatened by the spread of pathogens into their habitats. In captivity, clinically overt and often fatal disease seems to occur frequently. In conclusion, Encephalitozoon appears to be common in wild warm-blooded animals and these hosts may present important reservoirs for environmental contamination and maintenance of the pathogens. Similar to domestic animals, asymptomatic infections seem to occur frequently but in captive wild animals severe disease has also been reported. Detailed investigations into the epidemiology and clinical relevance of these microsporidia will permit a full appraisal of their role as pathogens.

Diversity of Enterocytozoon bieneusi genotypes among small rodents in southwestern Poland

Diversity of Enterocytozoon bieneusi genotypes in wild small rodent populations still remains incomplete and only few molecular studies have been conducted among these hosts. Therefore, the aim of this study was to determine whether small rodents, i.e., Apodemus agrarius, Apodemus flavicollis, Mus musculus and Myodes glareolus act as hosts of E. bieneusi and can play an important role in spore spreading in the environment of south-western Poland. Molecular analyses were conducted to determine pathogen genotypes. A total of 191 fecal and 251 spleen samples collected from 311 rodent individuals were examined for the occurrence of E. bieneusi by PCR amplifying ITS gene. The overall prevalence of E. bieneusi in rodent samples was 38.9%. The nucleotide sequences of ITS region of E. bieneusi revealed the presence a total of 12 genotypes with two being already known, i.e., D and gorilla 1 genotypes. The remaining ten are novel genotypes (WR1-WR10) which segregated into three groups in a neighbor joining phylogeny. This study reports for the first time E. bieneusi occurrence in wild living rodents in Poland and shows extensive genetic diversity within E. bieneusi isolates of rodent origin.