Serological survey of Encephalitozoon cuniculi infection in Japanese dogs

Prevalence of Encephalitozoon cuniculi Infection in Guinea Pigs (Cavia porcellus) in Poland with Different Clinical Disorders-A Pilot Study

Encephalitozoonosis is a disease caused by E. cuniculi. It is diagnosed primarily in rabbits but is less frequently so in other animal species. E. cuniculi is classified among Microsporidia-fungi frequently found in the environment, that are resistant to numerous external factors. Apart from rabbits, rodents form the next group of animals most exposed to infection with these pathogens. The objective of the study was to analyze the prevalence of E. cuniculi infection in guinea pigs with different clinical disorders. The study included 67 animals with E. cuniculi infection confirmed via real-time PCR. The infected animals most frequently exhibited nervous and urinary system symptoms, as well as issues with vision organs, while several animals were also recorded as having problems with the respiratory system and thyroid gland dysfunction. The study shows that encephalitozoonosis constitutes a significant problem in rodents kept as domestic animals, which in turn may be a source of infection for humans.

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.

Zoonotic Risk of Encephalitozoon cuniculi in Animal-Assisted Interventions: Laboratory Strategies for the Diagnosis of Infections in Humans and Animals

The involvement of animals for therapeutic purposes has very ancient roots. To date, it is clear that animal-assisted interventions (AAIs), in addition to ensuring the replacement of missing or deficient affects, improves psychophysiological parameters connected to human health. However, AAI could potentially present risks related to the transmission of infectious agents from animals to humans. Among these microorganisms, E. cuniculi is a microspore which induces pathological effects (fever, headache, nausea, vomiting, diarrhea, breathlessness, respiratory symptoms, and weakness) in both humans and animals. Consequently, an accurate and fast diagnosis of E. cuniculi infection, as well as the identification of new diagnostic approaches, is of fundamental importance. This literature review was carried out to provide an extensive and comprehensive analysis of the most recent diagnostic techniques to prevent and care for E. cuniculi-associated risks in the AAI field.

Is Encephalitozoon cuniculi of Significance in Young Dogs With Neurological Signs?

Encephalitozoon cuniculi is a microsporidium belonging to the phylum Microspora. A few reports have described the clinical significance of E. cuniculi infection in young dogs. In American and Japanese household dog populations, the seroprevalence was found to be 21%, indicating its wide-spread existence. To evaluate the clinical significance of E. cuniculi in a cohort of young dogs with neurological signs, the presence of the organism and possible response to treatment were studied. Over a 1-year period, all young dogs (<3 years old) that were referred with neurological signs were examined for the presence of E. cuniculi. Dogs were selected if serology revealed a clearly elevated IgM titer (>100) and/or if an EDTA-blood sample and/or urine sample tested positive by polymerase chain reaction (PCR). Sixteen dogs with various neurological signs were included in this study. Additional work-up included magnetic resonance imaging and cerebrospinal fluid analysis, but these revealed no abnormalities or indication of infection. All dogs were treated with fenbendazole for 10–30 days. Neurological signs disappeared completely in five dogs, 11 dogs continued to show neurological signs, and five dogs deteriorated and were euthanized, after which necropsy was performed in three. At necropsy no evidence of an E. cuniculi infection was found. We concluded that, although IgM titers and PCR indicated an E. cuniculi infection, it is most likely of limited clinical significance in young dogs.

A systematic review and meta-analysis on the global prevalence of microsporidia infection among dogs: a zoonotic concern

Background

Microsporidiosis is an emerging zoonotic disease that is considered a global public health concern. Dogs are suggested as one of potential reservoirs for transmitting the microsporidia infection to humans. However, there is little data on distribution of microsporidia in dogs. The current study aimed to evaluate the global prevalence and genetic diversity of microsporidia infection among the dog population.

Methods

We searched four major databases for studies reporting the prevalence of microsporidia in dogs until 30 May 2020. A random-effects model was used to estimate the overall and the subgroup-pooled prevalence of microsporidia across studies.

Result

Finally, a total of 32 studies (including 37 datasets) from 17 countries were included in this meta-analysis. The overall prevalence (95% CI) of microsporidia infection was estimated at 23.1% (13.5–36.8%) using microscopic methods, 20.9% (14.6–29%) using serological methods, and 8.4% (6.1–11.5%) using molecular methods. Molecular methods showed that the highest number of reports was related to Enterocytozoon bieneusi with a pooled prevalence of 6.5% (4.9–8.7%). Considering E. bieneusi genotypes, most studies reported the PtEb IX (10 studies) and the D (eight studies) genotypes.

Conclusion

These results emphasize the role of a dog as a reservoir host for human-infecting microsporidia. In addition, monitoring programs for human-infecting microsporidia in animals with close contact to humans should be considered.

Prevalence and Genotyping of Microsporidian Parasites in Dogs in Turkey: Zoonotic Concerns

Microsporidia are opportunistic pathogens that infect a wide range of invertebrates and vertebrates. To assess the potential role of dogs in the transmission of these zoonotic pathogens, a total of 282 fecal samples from dogs in the Central Anatolia Region of Turkey were analyzed by utilizing species specific polymerase chain reaction for the four most frequent human microsporidia. Two microsporidia species were recognized in 41 samples (14.5%). Encephalitozoon intestinalis was detected in 35 samples (12.4%) and it was the most common microsporidium. The second microsporidium, E. cuniculi, was identified in six (2.1%) of the samples. Sequence analysis of the intergenic spacer of the ribosomal ribonucleic acid (RNA) internal transcribed spacer (ITS) gene revealed the presence of three E. intestinalis haplotypes closely associated with each other. No polymorphic region was found among the ITS sequences of E. cuniculi isolates and they were characterized as genotype III. This study provides the first data on the zoonotic microsporidia species from dogs in Turkey.

Zoonotic microsporidia in dogs and cats in Poland

This study investigated the prevalence, genetic diversity, and zoonotic concerns of microsporidia in household dogs and cats in Poland. A total of 126 (82 dogs and 44 cats) fecal specimens were analyzed for the presence of specific DNA of Enterocytozoon bieneusi and Encephalitozoon spp. using a nested PCR protocol amplifying the internal transcribed spacer region of the rRNA gene. Microsporidia were found in 10 (7.9%) out of the 126 examined stool samples. Of the 82 dogs, 4 (4.9%) and 2 (2.4%) were positive for E. bieneusi (genotypes D and PtEbIX) and Encephalitozoon cuniculi genotype II, respectively. Of the 44 cats, 4 (9.1%) were positive for E. bieneusi (genotypes PtEbIX and eb52). Additionally, one cat (2.3%) was concurrently infected with E. bieneusi (PtEbIX) and E. cuniculi (genotype II). Considering that all detected microsporidia in dogs and cats have been previously associated with human microsporidiosis, companion animals may be a potential source of microsporidia infections in humans.

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.

Encephalitozoon cuniculi causes focal anterior cataract and uveitis in dogs

Three mongrel dogs, aged 10 months (case 1), 14 months (case 2) and 7.5 years (case 3), were presented because of ophthalmologic disorders of 4 months, 6 months and 7 years duration, respectively. All three dogs were offspring of stray dogs from Hungary and Serbia and had positive serum antibody titres against Encephalitozoon (E.) cuniculi. The two young dogs showed unilateral, the older dog bilateral chronic anterior uveitis with posterior synechia and focal anterior cortical cataract. The fundi that could be evaluated developed focal tapetal hyporeflective lesions in the course of the disease. Dogs 1 and 2 underwent removal of the lens via phacoemulsification. PCR of the lens material was positive for E. cuniculi strains IV and II, respectively. In dog 2 findings suggestive of microsporidia were detected underneath the anterior lens capsule by immunohistochemical staining. In all cases medical treatment consisted of systemic fenbendazole, prednisolone, and topical anti-inflammatory drugs, and additional brinzolamid/timolol for dog 3. For the time being all cases (follow up 23 months, 6 months and 3 months, respectively) are still on topical anti-inflammatory therapy. It is concluded that E. cuniculi infections can cause cataract and chorioretinal lesions in dogs.

First detection of an ignored parasite, Encephalitozoon cuniculi, in different animal hosts in Egypt

Encephalitozoon cuniculi is an obligate intracellular microsporidian parasite that infects a wide range of mammalian hosts. The present study investigated the prevalence of E. cuniculi in different animal hosts from different provinces of Egypt (Alexandria, Behera, and Assuit) using serological (IFAT and ELISA) and molecular (PCR) assays. A total of 324 serum and 274 urine samples were collected from seven different species of animals (cattle, buffaloes, sheep, goat, rabbit, dog, and rat). The results of serological examination confirmed the occurrence of antibodies against E. cuniculi in 38.9 % (126 out of 324) of the examined animals. The significant (P < 0.01) highest positivity was observed in goats (67 %) followed by buffaloes, rabbits, dogs, rat, and cattle (46.42, 41, 40, 36.2, and 28.1 %, respectively), while the least was recorded in sheep (9 %). Behera province showed the highest (P < 0.01) infection rate (40.68 %) followed by Alexandria and Assuit (39.2 and 22.73 %, respectively). The infection rate was significantly higher (P < 0.01) in females (45.34 %) than that in males (30.47 %). Positive cases were observed in all age categories. The highest infection rate (64.66 %) was recorded in the age group 1-5 years and the least was recorded in the age group <1 year (34.85 %).On the other hand, only five positive out of 274 urine samples (1.82 %) were detected by PCR. Our study provides a wide database on prevalence and epidemiology of an ignored parasite (E. cuniculi) for the first time in Egypt.

Evaluation of spore wall protein 1 as an alternative antigen for the diagnosis of Encephalitozoon cuniculi infection of farmed foxes using an enzyme-linked immunosorbent assay

The sequence encoding SWP1 was cloned from the genome of Encephalitozoon cuniculi. Recombinant SWP1 (rSWP1) was expressed in Escherichia coli and used to detect E. cuniculi infections in farmed foxes and dogs with an indirect enzyme-linked immunosorbent assay (ELISA) in the present study. The sera of foxes infected with E. cuniculi could be distinguished from the sera of foxes infected with Toxoplasma gondii, Neospora caninum, and Cryptosporidium parvum using the ELISA. In total, 198 fox samples collected in Liaoning were used to determine the prevalence of antibodies against this disease. The results showed that 16.7% of the fox serum samples were positive according to the ELISA using rSWP1, which agreed with the ELISA results based on recombinant PTP2 (rPTP2). The sensitivity and specificity of the ELISA based on rSWP1 suggest that this could be an alternative method for the diagnosis of E. cuniculi infections in foxes. In addition, 298 dog samples collected in Beijing, Shanghai, and Hunan were also detected in this study, of which six dog samples (2%) were positive according to the ELISA using rSWP1. To the best of our knowledge, this is the first study to demonstrate the serological prevalence of E. cuniculi infections in dogs and foxes in China.

Encephalitozoon infections in Rodentia and Soricomorpha in Japan

Encephalitozoon is an obligate intracellular microsporidian parasite that infects a wide range of mammalian hosts. In this study, we used nested PCR to investigate the presence of Encephalitozoon infection in Rodentia and Soricomorpha in Japan. We attempted to amplify and sequence Encephalitozoon-specific DNA from brain and viscera samples of 180 animals collected between 2008 and 2010. Forty-three samples (23.9%) from the orders Rodentia and Soricomorpha were positive for Encephalitozoon. This study is the first report of Encephalitozoon infection in Rodentia and Soricomorpha in Japan, and our findings suggest that these hosts may play a role in the spread of microsporidian spores in the environment.

Surveillance for an outbreak of Encephalitozoon cuniculi infection in rabbits housed at a zoo and biosecurity countermeasures

An outbreak of encephalitozoonosis occurred in a rabbit colony at a zoo in Japan. Throughout the two years after the onset, all 42 rabbits were investigated clinically, pathologically and serologically for prevention and control of the disease. Eleven rabbits (11/42, 26.2%) showed clinical symptoms. Of 38 rabbits examined to detect specific antibodies against Encephalitozoon cuniculi, 71.1% (n=27) were found seropositive; 20 out of 30 clinically healthy rabbits (except for 8 clinical cases) were seropositive. The infection rate was 76.2% (32/42), including 5 pathologically diagnosed cases. The results of serological survey revealed that asymptomatic infection was widespread, even among clinically healthy rabbits. However, encephalitozoonosis was not found by pathological examination in any other species of animals kept in the same area within the zoo. Isolation and elimination of the rabbits with suspected infection based on the results of serological examination were carried out immediately; however, encephalitozoonosis continued to occur sporadically. Therefore, all the remaining rabbits were finally slaughtered. Then, the facility was closed, and all the equipment was disinfected. After a two-month interval, founder rabbits were introduced from encephalitozoonosis-free rabbitries for new colony formation. Since then, encephalitozoonosis has not been seen in any animals at the zoo. In this study, biosecurity countermeasures including staff education, epidemiological surveillance and application of an "all-out and all-in" system for rabbit colony establishment based on serological examination were successfully accomplished with regard to animal hygiene and public health for the eradication of E. cuniculi.

Seroprevalence of Encephalitozoon cuniculi in dogs in the United States

Encephalitozoon cuniculi is an obligate intracellular microsporidian parasite that can result in clinical and subclinical infection in many species. It is also considered the cause of a potential zoonotic disease. In the present study, a serological survey was conducted using samples from pet dogs in the state of Florida. Twenty-seven of 125 serum samples, or 21.6%, were found to demonstrate reactivity by ELISA, with titers ranging from 1:32 to 1:512. There were no significant differences by age or sex. This is the first report on the detection of E. cuniculi antibodies in dogs in the United States.