Encephalitozoonosis in rabbits

The global prevalence of microsporidia infection in rabbits as a neglected public health concern: A systematic review and meta-analysis

Microsporidia are intracellular parasites with significant impact on both animal and human health. The prevalence of microsporidia infections in rabbits, including the genera Enterocytozoon and Encephalitozoon, underscores the importance of understanding their epidemiology for effective control strategies. This systematic review and meta-analysis estimated the global prevalence of microsporidia infection in rabbits using five databases (Scopus, PubMed, Embase, Web of Science, and Google Scholar) to retrieve articles published between 03 December 2003 and 26 March 2023. The global prevalence was estimated with a 95 % confidence interval. All statistical analyses conducted were based on meta-package of R (version 3.6.1). A p-value lower than 0.05 was interpreted as statistically significant. A total of 71 studies comprising 72 datasets were included, yielding a global pooled prevalence of microsporidia infections in rabbits at 0.312 (0.250-0.378). The prevalence varied significantly by continent with highest observed in North America (0.495, 0.151-0.842). Slovenia had the highest pooled prevalence (0.714, 0.654-0.773). Encephalitozoon cuniculi accounted for the highest prevalence (0.338, 0.271-0.407). The findings highlight the global distribution of microsporidia in rabbit populations, emphasizing the zoonotic potential and public health implications. The predominance of E. cuniculi underscores its importance as a widespread pathogen affecting both animal and human health. The data underscore the need for continued surveillance and monitoring, particularly in regions with high prevalence.

Novel zoonotic Enterocytozoon and Encephalitozoon genotypes in domestic pigeons (Columba livia domestica) in Iran: Public health implications

To determine the occurrence of microsporidiosis in domestic pigeons in Iran, privately-owned pigeons presenting weight loss and diarrhea were tested through molecular and histopathological methods. Multiplex-PCR findings showed 57%, 30%, and 14% positivity for Enterocytozoon, Encephalitozoon, and mixed infection in the fecal samples, respectively. A novel Enterocytozoon bieneusi genotype, named IrnEb1, falling into zoonotic group 1 of E. bieneusi, and a novel genotype of Encephalitozoon hellem, named Irn2E, clustering as a sister taxon to genotype 2B were identified in pigeons for the first time using Sanger sequencing and phylogenetic analyses. Histopathological examination revealed the occurrence of non-suppurative enteritis, nephritis, pneumonia, hepatitis, and encephalitis associated with focal necrosis and inflammatory cell infiltration. Data shown herein present a high prevalence of microsporidiosis in pigeons in Iran. Considering that both detected microsporidian species are zoonotic parasites, these findings suggest that the infected pigeons could pose a risk to public health.

Encephalitozoon cuniculi Infection in Rabbits (Oryctolagus cuniculus): Data from an International Survey of Exotic and Small Animal Veterinarians

In 2022-2023, the first survey of clinicians regarding Encephalitozoon cuniculi infection of rabbits was undertaken. The purpose was to assess the current worldwide knowledge of clinicians regarding influence of breed and age, clinical presentations, use of various diagnostic tools, and treatment regimens and to explore how responses may differ by geographic location. Identifying mostly as exotic animal clinicians, 339 respondents participated, with nearly half from the United States and the remainder from 35 other countries. Neurological signs were most consistently reported as associated with Encephalitozoon cuniculi and the most recurrent clinical case presentation. Other responses showed differences by geographic location. For example, age predilection for disease varied, with 71.1% of international respondents indicating that infection was more common in young rabbits versus 28.9% who suggested it was more frequent in older rabbits. This was significantly different (p = 0.001) from the information from respondents from the United States, where 48.0% indicated that younger rabbits had an increased incidence versus 52.0% who indicated that older age increased occurrence. While some differences may be related to the practice composition and the training level of respondents, many responses were in alignment with the existing literature. Future inquiries should focus more on these discrepancies to aid in generating guidelines for the diagnosis and treatment of this infectious disease.

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.

Encephalitozoon cuniculi Infection of Domestic Rabbits (Oryctolagus cuniculus) in Slovenia between 2017 and 2021

Encephalitozoon cuniculi is a microsporidial parasite that primarily infects domestic rabbits (Oryctolagus cuniculus). It is the causative agent of encephalitozoonosis, a disease with an internationally recognized seroprevalence among rabbits. This study determines the presence, clinical manifestation, and serological status of encephalitozoonosis in pet rabbits in Slovenia using various diagnostic procedures. From 2017 to 2021, 224 pet rabbit sera were collected and tested for encephalitozoonosis with the indirect immunofluorescence assay. Immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies against E. cuniculi were confirmed in 160 (65.6%) cases. Most seropositive rabbits suffered from neurological clinical signs or signs of gastrointestinal disorders such as recurrent hypomotilities, chronic weight loss, cachexia, or anorexia, and fewer showed clinical signs related to the urinary system or phacoclastic uveitis. A quarter of the positively tested rabbits presented without clinical signs. Hematological and biochemical blood analysis confirmed that seropositive animals had elevated globulin and deviated albumin levels in comparison to the normal reference values of non-infected animals. Furthermore, rabbits with neurological clinical signs showed statistically significant higher levels of globulins and total protein. Sixty-eight whole-body radiographs and thirty-two abdominal ultrasound reports were analyzed, looking for changes in the shape or size of the urinary bladder, presence of urinary sludge or uroliths, and any abnormalities related to the kidneys (shape, size, or nephrolites). The results suggest that neurological defects in the urinary bladder caused by E. cuniculi lead to a distended urinary bladder and consequently dysuria, incontinence, urine scalding, and sludgy urine.

Acute renal injury from thrombotic microangiopathy associated with enteritis in New Zealand white rabbits

Over a 3-y period, 12 adult New Zealand white (NZW) rabbits were presented for postmortem examination following variably long periods of inappetence and soft-to-liquid stool production. Postmortem findings included serosanguineous fluid in abdominal and thoracic cavities, dark-red-to-white renal foci, reddened intestinal serosa, and pulmonary edema. Microscopically, mesangial changes and thrombi were observed in renal glomeruli, and mild-to-severe enteritis was observed. These findings resemble hemolytic uremic syndrome, which typically follows enterocolitis associated with Shiga toxin (Stx)-producing Escherichia coli infection. In our case series, various gram-negative bacteria, most commonly E. coli, were isolated from the intestinal tracts; however, Stx production was not demonstrated. Evidence of Encephalitozoon cuniculi infection, a common cause of renal disease in rabbits, was also not found. Our cases suggest that gram-negative enteric bacteria should be included in the differential diagnosis of renal disease in NZW rabbits, especially in cases with an accompanying clinical history of gastrointestinal disorder.

Serological survey for antibodies to Encephalitozoon cuniculi and Toxoplasma gondii in pet rabbits in eastern coastal areas of China

Encephalitozoon cuniculi (E. cuniculi) is a microsporidian parasite commonly detected in rabbits and can infect humans and cause encephalitozoonosis. And Toxoplasma gondii is a prevalent parasite distributed worldwide and can infect almost all warm-blooded animals, including humans. The aim of the current study was to investigate the seroprevalence of E. cuniculi and Toxoplasma gondii, and risk factors of infection in pet rabbits reared in eastern coastal areas of China (Tianjin, Shandong, Jiangsu, Zhejiang, Shanghai and Fujian). Total 222 blood samples of pet rabbits were collected from local veterinary hospitals. The seropositivity rates of E. cuniculi were 16.22% (36/222) according to an Enzyme-linked immunosorbent assay (ELISA). Female pet rabbits was significantly higher than that in males (P=0.002), Zhejiang were markedly higher than those in Jiangsu and Shanghai (P=0.017, P=0.022), and cross-breed rabbits were dramatically higher than those in Chinchilla, New Zealand white, Rex (P=0.02, P=0.006, P=0.008). The seroprevalence of T. gondii was 13.06% (29/222) by the method of ELISA. The seroprevalence in Zhejiang was significantly higher than that in Shanghai (P=0.017). No difference in seroprevalence was detected with respect to the gender, age, species, health status, or season. These findings show that E. cuniculi and T. gondii are present and spread in pet rabbits. Therefore, pet rabbits should be considered as an important reservoir of encephalitozoonosis for humans and maybe important implication for public health in eastern coastal areas of China.

Encephalitozoon spp. as a potential human pathogen

Encephalitzoon spp. are microsporidia, and intracellular opportunistic pathogens. The hosts of these pathogens include vertebrates, invertebrates, and certain protozoa. In people microsporidia may be opportunistic pathogens for immunocompromised patients (with AIDS or after organ transplantation). Infection with these microorganisms was also described in persons with diarrhea and corneal diseases.

The species causing rare infections in humans, Encephalitozooncuniculi, had previously been described from animal hosts. However, several new microsporidial species, including E. intestinalis and E. hellem, have been discovered in humans, raising the question of their natural origin. Vertebrate animals are now identified as hosts for all three microsporidial species infecting humans, implying a zoonotic nature of these microorganisms. Molecular studies have identified phenotypic and/or genetic variability within these species, indicating that they are not uniform, and have allowed the question of their zoonotic potential to be addressed. The focus of this review is to present the zoonotic potential of E. intestinalis, E. cuniculi, and E. hellem.

Seroprevalence of Encephalitozoon cuniculi and Toxoplasma gondii antibodies and risk-factor assessment for Encephalitozoon cuniculi seroprevalence in Finnish pet rabbits (Oryctolagus cuniculus)

Background

Neurological signs, such as head tilt, torticollis, paralysis, and seizures, are common in rabbits. Differential diagnoses include two zoonotic infections caused by the microsporidial fungi Encephalitozoon cuniculi and the apicomplexan protozoa Toxoplasma gondii. Both infections are mainly latent in rabbits but may cause severe or even fatal disease. Although several international studies have reported the seroprevalence of these pathogens in different commercial rabbit populations, similar prevalence studies and risk-factor analyses among family-owned pet rabbits are uncommon and lacking in Scandinavia. We sought to estimate the seroprevalence and possible risk factors for E. cuniculi and T. gondii among Finnish pet rabbits. We used ELISA to measure E. cuniculi IgG seroprevalence of 247 rabbits and modified direct agglutination test for T. gondii seroprevalence of 270 rabbits. Samples were collected as part of the Finnish Pet Rabbit Health Research project. Internet-based questionnaires (n = 231) completed by the rabbit owners were used for risk-factor analysis.

Results

The apparent seroprevalence of E. cuniculi was 29.2% and true seroprevalence of T. gondii 3.9%. Risk factors were analysed only for E. cuniculi due to the low T. gondii seroprevalence. The final multivariable logistic regression model revealed that rabbits spending the whole summer outdoors had a higher risk of being E. cuniculi seropositive than rabbits with limited outdoor access. Additionally, rabbits living in households with only one or two rabbits had higher risk of being E. cuniculi seropositive than those in multi-rabbit households.

Conclusions

Nearly one third of Finnish pet rabbits participating in this study had E. cuniculi IgG antibodies, indicating previous exposure to this pathogen. The prevalence is similar to that reported previously in clinically healthy rabbit populations in UK and Korea. While the seroprevalence of T. gondii was low (3.9%), antibodies were detected. Therefore, these zoonotic parasitic infections should be considered as differential diagnoses when treating rabbits.

Intestinal Microsporidia Infection in Leukemic Children: Microscopic and Molecular Detection

BACKGROUND

Microsporidia infection was originally described as an immunocompromised associated pathogen. Limitations to correct microscopic diagnosis of microsporidia include size of the organism presenting a challenge even to a highly competent laboratory expert.

OBJECTIVE

The present study aimed to detect microsporidia infection among leukemic children. The performance of modified trichrome stain and PCR in the diagnosis of microsporidia was evaluated with further speciation.

METHODS

Stool samples of 100 leukemic children on chemotherapy were examined microscopically for microsporidia. DNA was extracted from all samples. Amplification was performed by conventional and nested PCR. Sequencing of amplified products was performed on unspeciated samples.

RESULTS

Microsporidia were detected in 23% of the children by MTS and 29% by PCR. The 29 positive samples were subjected to PCR for speciation. Enterocytozoon bieneusi was found to predominate in 20 cases, Encephalitozoon intestinalis in three cases, two cases had co-infection, and the remaining four samples were not amplified with either E. bieneusi or E. intestinalis specific primers. By DNA sequencing of the unspeciated samples, three samples shared high homology with Encephalitozoon hellem and one sample with Encephalitozoon cuniculi. Referring to PCR as a gold standard, MTS exhibited 72.4% sensitivity and 97.2% specificity with 90% accuracy. Among a number of studied variables, diarrhea and colic were significantly associated with microsporidia infection when diagnosed by either technique.

CONCLUSION

The use of sensitive and discriminative molecular tools will contribute to determining the true prevalence of microsporidiosis and possibly their potential transmission source depending on species identification.

Toxicity Evaluation of a Novel Rapamycin Liposomal Formulation After Subconjunctival and Intravitreal Injection

Purpose: Safety and toxicity evaluation of a novel, liposome-encapsulated rapamycin formulation, intended for autoimmune ocular disorders. Methods: The formulation was assessed by micronucleus polychromatic erythrocyte production, irritability by Hen's Egg Test-Chorioallantoic Membrane (HET CAM), sterility, and pyrogenicity testing. Subconjunctival (SCJ) and intravitreal (IVT) administration of the formulation were performed to evaluate subacute and acute toxicity, respectively. Differences between groups in biochemical and hematological parameters were evaluated by analysis of variance and t-tests. Numeric score was assigned to histopathological classification. Electroretinography (ERG) testing was also performed. Data were analyzed by a 1 way no parametric Kruskal-Wallis and the Mann-Whitney tests. Significance was considered when P < 0.05. Results: No significant toxicity directly related to the preparation was detected. Micronucleus count, mucous irritation score, and pyrogenicity results were negative. Pathology demonstrated no damage related to the formulation after SCJ injection. After IVT injection, only lens injury associated with technique was observed. Retinal function was also conserved in ERG. Conclusions: The preparation evaluated offers a good toxicity and safety profile when injected in a SCJ or IVT manner in an animal model. A clinical trial conducted in humans is highly warranted, as it could reveal an alternative immunosuppressive treatment for ophthalmological immune-mediated pathologies.

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.

Characterization of humoral and cell-mediated immunity in rabbits orally infected with Encephalitozoon cuniculi

Encephalitozoonosis is a common infectious disease widely spread among rabbits. Encephalitozoon cuniculi, is considered as a zoonotic and emerging pathogen capable of infecting both immunocompetent and immunocompromised hosts. The aim of the study was to describe in detail the spread of the E. cuniculi in a rabbit organism after experimental infection and the host humoral and cellular immune response including cytokine production. For that purpose, healthy immunocompetent rabbits were infected orally in order to simulate the natural route of infection and euthanised at 2, 4, 6 and 8-weeks post-infection. Dissemination of E. cuniculi in the body of the rabbit was more rapid than previously reported. As early as 2 weeks post-infection, E. cuniculi was detected using immunohistochemistry not only in the intestine, mesenteric lymph nodes, spleen, liver, kidneys, lungs and heart, but also in nervous tissues, especially in medulla oblongata, cerebellum, and leptomeninges. Based on flow cytometry, no conspicuous changes in lymphocyte subpopulations were detected in the examined lymphoid organs of infected rabbits. Cell-mediated immunity was characterized by ability of both CD4⁺ and CD8⁺ T cells to proliferate after stimulation with specific antigens. Th1 polarization of immune response with a predominance of IFN-γ expression was detected in spleen, mesenteric lymph nodes and Peyer’s patches. The increased expression of IL-4 and IL-10 mRNA in mixed samples from the small intestine is indicative of balanced control of IFN-γ, which prevents tissue damage. On the other hand, it can enable E. cuniculi to survive and persist in the host organism in a balanced host-parasite relationship. The Th17 immunity lineage seems to play only a minor role in E. cuniculi infection in rabbits.

Immunohistochemical localization of TNF-α and IL-4 in granulomas of immunocompetent and immunosuppressed New Zealand white rabbits infected with Encephalitozoon cuniculi

Encephalitozoon cuniculi is a fungi-related, obligate, zoonotic, spore-forming intracellular eukaryotic microorganism. This emerging pathogen causes granulomas to form in the brain and kidneys of infected individuals. The objective of the current study was to detect the distribution of TNF-α- and IL-4-positive cells using immunohistochemistry within these granulomas in both infected immunocompetent (group A) and immunosuppressed (group B) New Zealand white rabbits. In the brain, labeled TNF-α immune cells were mainly located in the granuloma peripheries in group B. Granulomas examined in the kidneys of groups A and B were TNF-α positive, but were significantly different (p < 0.001) when compared with the brain. IL-4-producing immune cells in the brain and kidneys were disseminated within granulomas in groups A and B; however, no significant difference (p > 0.05), was observed. IL-4 positive cells were more numerous in brain sections of group B and differed significantly (p < 0.05) when compared with kidneys. Granulomas were not observed in control animals (groups C and D). In conclusion, we identified TNF-α positive cells in both the brain and kidneys of immunocompetent and immunosuppressed animals; IL-4 positive cells were numerous in the brains of immunosuppressed rabbits; however, in terms of percentage were numerous in the brains of immunocompetent rabbits. Immunosuppression appeared to stimulate a change in the cellular phenotype of Th1- to Th2-like granulomas in the brain and kidneys via an unknown mechanism. Expression of pro- and pre-inflammatory cytokines in microsporidian granulomas suggests a mechanism by which E. cuniculi evades the immune response, causing more severe disease. These results increase our understanding of TNF-α and IL-4-positive cells within the E. cuniculi granuloma microenvironment.

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.

First molecular evidence of ocular transmission of Encephalitozoonosis during the intrauterine period in rabbits

Many reports have been published on the suspected vertical transmission of Encephalitozoon cuniculi; however, prior to 2003, these reports were based on circumstantial evidence, such as histopathological, immunohistochemical, or serological diagnosis of the infection. In 2003, vertical transmission of the parasite was confirmed by detection of E. cuniculi DNA in fetuses with the nested polymerase chain reaction (PCR) technique. However, the passage of the parasite to eyes of fetus during the intrauterine stage still requires verification. In the current study, natively infected with parasite spores female rabbits were mated with non-infected males. All resulting offspring that died before ten postpartum days were investigated using molecular techniques to confirm the intrauterine transmission of the parasite to the offspring' eyes. In total, 119 DNA samples from rabbit offspring tissues were collected from blood, kidney, brain, eye (both eyes were used as single samples), lung, placenta, liver and heart were used for PCR. Parasitic DNA in the eyes of offspring was detected (54%) 6 of 11 naturally seropositive mother rabbits. PCR results were found to be positive for the eyes of 63% (19/30) of the offsprings from seropositive rabbits. Therefore, mother rabbits naturally infected with E. cuniculi showed the molecular presence of the parasite in their offspring' eyes. Sequence analysis confirmed the partial DNA sequence data of E. cuniculi and blast analysis identified the agent as genotype I. These results confirm transmission of E. cuniculi to rabbit offspring' eyes in the intrauterine period. This is the first molecular evidence to show ocular transmission of the infection via an intrauterine route in rabbits.

Encephalitozoonosis infection in a traditional rabbit farm with neurological manifestations

Encephalitozoon cuniculi, a zoonotic and opportunistic pathogen, can cause latent infection, especially in lagomorphs. Nowadays, this member of the Eukaryotes has drawn significant attention in the fields of veterinary and public health. The purpose of this study was to determine the seroprevalence of infection in a New Zealand rabbit farm that has a clinical history of neurological manifestations including head tilt ataxia, aggressiveness, seizures, and circling and rotational movements around the body length axis, but the general conditions and food intake were normal. Blood samples were taken from 42 breeding rabbits and researched for E. cuniculi antibodies. Out of that, 25 (59%) animals resulted positive against the pathogen. The rabbit was found to be seropositive for E. cuniculi antibodies, but negative for Toxoplasma gondii and Listeria monocytogenes antibodies. Hematological and serum biochemical parameters were measured at reference intervals. No brain tissue impairment was observed the computed tomography (CT) scan. As a result of these histopathological findings, the brain cortex presented severe neuronal degeneration and partial myelin loss, with reactive diffuse gliosis against the parasite spores was observed to the histopathology. These results are possibly related to the early stage of infection because the parasitic infestation comprise long time spreading. E. cuniculi DNA was detected on brain tissues using polymerase chain reaction (PCR), and it partial DNA sequence was identified as E. cuniculi genotype I.

Clinical Signs, Diagnosis, and Treatment of Encephalitozoon cuniculi Infection in Rabbits

Central vestibular dysfunction caused by Encephalitozoon cuniculi frequently mimics the condition of a peripheral disorder. A negative antibody titer rules out E cuniculi as the cause of present clinical signs. Cerebrospinal fluid analysis including polymerase chain reaction is considered an inappropriate diagnostic method for in vivo diagnosis of encephalitozoonosis. The usefulness of glucocorticoid anti-inflammatories in the treatment of encephalitozoonosis is called into question. Encouraging activity early in the course of disease and adding in therapeutic exercise may represent the most important part of therapy in rabbits with vestibular dysfunction associated with encephalitozoonosis.

Quantitative analysis of TNF-α, IL-4, and IL-10 expression, nitric oxide response, and apoptosis in Encephalitozoon cuniculi-infected rabbits

The expression of tumor necrosis factor (TNF) -α, interleukin (IL) -4 and IL-10, as well as apoptosis and nitric oxide (NO) levels were measured in the brain and kidneys of immunocompetent and immunosuppressed New Zealand White rabbits infected with Encephalitozoon cuniculi. All of the animals had clinical signs histopathological lesions compatible with encephalitozoonosis and were E. cuniculi-positive by using a carbon immunoassay test. Encephalitozoon cuniculi infection promoted the expression of TNF-α and NO production in the kidneys of infected rabbits, and a synergic effect was observed in animal treated with dexamethasone. The IL-4 expression was similar in the brain and kidneys of infected rabbits, regardless of their immunologic status. The IL-10 mRNA expression in the brain of infected immunosuppressed rabbits was elevated when compared with positive controls. Apoptosis of granuloma mononuclear-like cells was detected in immunocompetent E. cuniculi-infected rabbits, but it was more evident in infected-immunosuppressed animals. Nitric oxide levels were elevated both in immunocompetent and immunosuppressed infected animals, but it was more apparent in the kidneys. These data suggest that modulation of the immune response by E. cuniculi could contribute to the survival of the parasite within phagocytic cells in granulomas via an as yet undetermined mechanism.

[Nephritis in a Staffordshire Terrier puppy caused by Encephalitozoon cuniculi genotype I]

An 8-week-old puppy was presented to the clinic because of anorexia, polyuria, polydipsia and azotemia. The urinary sediment displayed large amounts of protozoan-like organisms, which could be identified by PCR as Encephalitozoon cuniculi genotype I. In the immunofluorescence antibody test (IFAT) an antibody titer against E. cuniculi of 1  :  2560 was found. The dog was treated with fenbendazole over 3 weeks. After 3 months, an antibody titer against E. cuniculi could no longer be detected. The dog recovered completely. This rare case demonstrates that E. cuniculi genotype I can cause clinical disease in dogs with renal involvement, which can be successfully treated with fenbendazole.

Application of mass spectrometry to elucidate the pathophysiology of Encephalitozoon cuniculi infection in rabbits

Encephalitozoon cuniculi is a microsporidian species which can induce subclinical to serious disease in mammals including rabbits, a definitive natural host. The pathophysiology of infection has not been comprehensively elucidated. In this exploratory study, we utilized two mass spectrometry approaches: first, the analysis of the humoral response by profiling the microsporidian antigens as revealed by Western blot screening, and second, implementing the iTRAQ®-labeling protocol to focus on the changes within the host proteome during infection. Seven E. cuniculi proteins were identified at one-dimensional gel regions where specific seropositive reaction was observed by Western blot, including polar tube protein 3, polar tube protein 2, and for the first time reported: heat shock related 70kDa protein, polysaccharide deacetylase domain-containing protein, zinc finger protein, spore wall and anchoring disk complex protein EnP1, and translation elongation factor 1 alpha. In addition, there was a significant increase of nine host proteins in blood samples from E. cuniculi-diseased rabbits in comparison with non-diseased control subjects undergoing various inflammatory processes. This included serum paraoxonase, alpha-1-antiproteinase F precursor and alpha-1-antiproteinase S-1 which have presumptive catalytic activity likely related to infection control, and cystatin fetuin-B-type, an enzyme regulator that has been poorly studied to date. Notably, 11 proteins were found to be statistically increased in rabbits with neurological versus renal clinical presentation of E. cuniculi infection. Overall, this novel analysis based on mass spectrometry has provided new insights on the inflammatory and humoral responses during E. cuniculi infection in rabbits.

Application of Western blot analysis for the diagnosis of Encephalitozoon cuniculi infection in rabbits: example of a quantitative approach

Diagnosis of Encephalitozoon cuniculi infection in rabbits remains a major veterinary issue. ELISA or immunofluorescence assays are the current reference standards of serological tests. However, these conventional techniques suffer from a lack of accuracy for distinguishing active from past infections, as a positive serostatus is common in clinically normal rabbits. In this study, we assessed the diagnostic performance of Western blot (WB) to detect both anti-E. cuniculi immunoglobulin G (IgG) and immunoglobulin M (IgM) in comparison with ELISA and to address the intensity of the immune response through a quantitative approach. Positive WB results were highly correlated with the E. cuniculi-related diseased status (P < 0.0001). Although it was more labor intensive and less standardized, quantitative WB provided detailed comparable analysis regarding the humoral response and diagnostic performance similar to ELISA testing with statistically higher sensitivity (88.4 vs. 76.1% for IgG detection and 84.3 vs. 70.4% for IgM, P < 0.01). Several specific WB bands were shown to be significantly associated with concomitant clinical signs, like the one located at 50 kDa (OR = 8.2, [2.4-27.7], P = 0.0008) for IgG and (OR = 27.9, [4.2-187.9], P = 0.0006) for IgM. Therefore, the quantitative WB may have application in veterinary diagnostic laboratories to increase the accuracy of the clinical diagnosis of E. cuniculi infection. In addition, this tool may help to further understand the development and function of the humoral immune response to this infectious agent.

Encephalitozoon cuniculi in rabbits: Serological screening and histopathological findings

Serological prevalence of E. cuniculi infection was assessed in 183 rabbits from central Italy. In seropositive deceased rabbits, histopathological lesions were also evaluated. Sera from 118 rabbits from 6 intensive farms, 10 rabbits from 6 family farms, 16 rabbits from a zoo, 30 rabbits from 5 research laboratories and 9 pet rabbits from 9 different owners, were tested by an enzyme-linked immunosorbent assay. Data were statistically analysed. Tissue samples from brain and kidney of 10 deceased rabbits were formalin-fixed and subsequently analysed by histopathology and immunohistochemistry. Anti-E. cuniculi antibodies were found in 129/183 (70.5%) analysed sera. At statistical analysis, E. cuniculi seropositivity was significantly higher (p<0.05) in industrial and zoo rabbits. At histology, different degrees of pathological lesions were found in serological positive (9) deceased animals. In three rabbits deceased after showing neurological signs, the severity of the lesions was interpreted as a likely cause for their death.

Triple infection with agamid adenovirus 1, Encephaliton cuniculi-like microsporidium and enteric coccidia in a bearded dragon (Pogona vitticeps)

A 2-month-old juvenile central bearded dragon was presented for anorexia and cachexia. Another specimen from the same cage had died suddenly 2 weeks prior. Fecal analysis revealed a high quantity of Isospora amphiboluri and a few pinworm eggs. Other examinations were not performed and the animal died a few days later despite supportive care. A third individual from the same cage presented with anorexia and a distended cœlom and was euthanized. In this third dragon, histological examination revealed intestinal coccidiosis, basophilic intranuclear inclusions compatible with adenovirus infection, acute hepatic necrosis with intrahepatocytic and intraenteritic organisms typical of microsporidia and renal gout. A PCR confirmed the diagnosis of adenovirosis. Sequencing showed that the PCR product was 100% identical to the corresponding portion of the agamid adenovirus 1 genome. A PCR for the detection of Encephalitozoon (E.) cuniculi was positive. Partial sequencing revealed 100% identity to an E. cuniculi-like organism previously found in bearded dragons. In cases where environmental factors such as poor hygiene or stress can be excluded, the presence of opportunistic pathogens in high numbers can be due to a systemic (viral) infection with temporary immunosuppression.

Interferon γ and interleukin 10 responses in immunocompetent and immunosuppressed New Zealand White rabbits naturally infected with Encephalitozoon cuniculi

Levels of interferon (IFN)-γ and interleukin (IL)-10 were measured in the serum of immunocompetent and immunosuppressed New Zealand White rabbits naturally infected with Encephalitozoon cuniculi. IFN-γ levels were elevated in infected rabbits, and a synergic effect was observed in animals treated with the immunosuppressive agent dexamethasone (Dex). The role of IL-10 in infected rabbits remains unclear, as IL-10 levels were similar to those of negative controls. Dex appeared to exhibit a proinflammatory effect, as IFN-γ levels were elevated in infected immunosuppressed rabbits. Similarly, Dex exhibited a synergic effect in infected immunosuppressed rabbits, as evidenced by the elevation in IFN-γ production. These data indicate that the immune response to this glucocorticoid should be considered in the design of future animal model studies of immunosuppression.

Case Report of Bilateral 3-4 Metatarsal Syndactyly in a Pet Rabbit

We report the first case of spontaneous syndactyly reported in a pet rabbit. Syndactyly only caused an atypical gait in the rabbit. The radiological study revealed bilateral 3rd and 4th metatarsal bones fused in its entire length preserving normal joint surfaces resembling syndactyly type Ia. The cause of this congenital malformation was unknown.

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.

Serological survey on some pathogens in wild brown hares (Lepus europaeus) in Central Italy

OBJECTIVE

To determine the exposure of wild brown hares [Lepus europaeus (L. europaeus), pallas] to Anaplasma phagocytophilum (A. phagocytophilum), Borrelia burgdorferi (B. burgdorferi) sensu lato, Encephalitozoon cuniculi (E. cuniculi), Leishmania sp., Neospora caninum (N. caninum) and Toxoplasma gondii (T. gondii).

METHODS

Two hundred twenty-two blood serum samples of wild brown hares captured in protected areas of the province of Pisa (Central Italy) were tested to detect antibodies against the reported pathogens.

RESULTS

Thirty one (14.0%) animals resulted positive for at least one tested agent, with antibody titres ranging from 1:20 to 1:320. In particular, 13 (5.8%) samples were positive to B. burgdorferi s.l., 11 (4.9%) to N. caninum, 3 (1.3%) to T. gondii, 2 (0.9%) to A. phagocytophilum and 2 (0.9%) to Leishmania sp. No samples scored positive to E. cuniculi. Four animals (14.8%) resulted coinfected with 2 different pathogens.

CONCLUSION

The obtained results showed that B. burgdorferi s.l. N. caninum, T. gondii, A. phagocytophilum and Leishmania sp. circulate in wild brown hares in Central Italy, suggesting a possible role of L. europaeus as reservoir of these pathogens. The obtained results showed that autochthonous wild brown hares living in Central Italy have been exposed to several pathogens circulating in this area, suggesting a possible role of L. europaeus as reservoir.

Encephalitozoon cuniculi: Grading the Histological Lesions in Brain, Kidney, and Liver during Primoinfection Outbreak in Rabbits

This is the first confirmed report of Encephalitozoon cuniculi (E. cuniculi) in farm meat rabbits located in Northern Mexico. Eighty young rabbits exhibited clinical signs of this zoonotic emerging disease, like torticollis, ataxia, paresis, circling, and rolling. Samples of brain, kidney, and liver were examined for histology lesions. For the first time the lesions caused by E. cuniculi were graded according to their severity (I, II, and III) and the size of the granulomas (Types A, B, and C). The main cerebral injuries were Grade III, coinciding with the presence of Type C granulomas. The cerebral lesions were located in the cortex, brain stem, and medulla. The renal lesions were also Grade III distributed throughout cortex and renal medulla, with no granuloma formation. The involvement of hypersensitivity Types III and IV is suggested. All of the rabbits were seropositive to E. cuniculi by CIA testing, suggesting that this zoonotic and emerging pathogen is widely distributed among animals intended for human consumption. We believe this work could be used as a guide when examining E. cuniculi and will provide direction to confirm the diagnosis of this pathogen.

Microsporidiosis in Vertebrate Companion Exotic Animals

Veterinarians caring for companion animals may encounter microsporidia in various host species, and diagnosis and treatment of these fungal organisms can be particularly challenging. Fourteen microsporidial species have been reported to infect humans and some of them are zoonotic; however, to date, direct zoonotic transmission is difficult to document versus transit through the digestive tract. In this context, summarizing information available about microsporidiosis of companion exotic animals is relevant due to the proximity of these animals to their owners. Diagnostic modalities and therapeutic challenges are reviewed by taxa. Further studies are needed to better assess risks associated with animal microsporidia for immunosuppressed owners and to improve detection and treatment of infected companion animals.

Biology and Diseases of Rabbits

Beginning in 1931, an inbred rabbit colony was developed at the Phipps Institute for the Study, Treatment and Prevention of Tuberculosis at the University of Pennsylvania. This colony was used to study natural resistance to infection with tuberculosis (Robertson et al., 1966). Other inbred colonies or well-defined breeding colonies were also developed at the University of Illinois College of Medicine Center for Genetics, the Laboratories of the International Health Division of The Rockefeller Foundation, the University of Utrecht in the Netherlands, and Jackson Laboratories. These colonies were moved or closed in the years to follow. Since 1973, the U.S. Department of Agriculture has reported the total number of certain species of animals used by registered research facilities (1997). In 1973, 447,570 rabbits were used in research. There has been an overall decrease in numbers of rabbits used. This decreasing trend started in the mid-1990s. In 2010, 210,172 rabbits were used in research. Despite the overall drop in the number used in research, the rabbit is still a valuable model and tool for many disciplines.

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.

Encephalitozoon cuniculi in pet rabbits: diagnosis and optimal management

Encephalitozoonosis is a significant microsporidial disease of captive pet rabbits (Oryctolagus cuniculus). This article overviews the life cycle, pathogenesis, and host immune response to the parasite. Clinical presentation, differential diagnoses, antemortem diagnostics, and postmortem diagnosis will be discussed. International seroprevalence data and histologic prevalence estimates in the US are presented. A review of current treatment and control recommendations are discussed based on extensive review of controlled studies, which have found fenbendazole to be effective for limiting spread of the disease.

Comparison of an indirect fluorescent antibody test with Western blot for the detection of serum antibodies against Encephalitozoon cuniculi in cats

Current clinical research indicates that Encephalitozoon (E.) cuniculi infections in cats may be underdiagnosed, especially in animals with typical ocular signs (cataract/anterior uveitis). Although molecular detection of the pathogen in tissue appears promising, serology remains the major diagnostic tool in the living animal. While serological tests are established for the main host of E. cuniculi, the rabbit, the routine serological diagnosis for cats still needs validation. The aim of the study was to evaluate the consistency of indirect fluorescence antibody test (IFAT) and Western blot (WB) for the detection of IgG antibodies against E. cuniculi in the serum of 84 cats. In addition, PCR of liquefied lens material or intraocular fluid was performed in those of the cats with a suspected ocular E. cuniculi infection. Twenty-one cats with positive PCR results were considered as a positive reference group. Results obtained by IFAT and WB corresponded in 83/84 serum samples, indicating a very good correlation between both serological methods. Using WB as the standard reference, sensitivity and specificity for the detection of antibodies against E. cuniculi by the IFAT were 97.6 and 100%, respectively. The positive and negative predictive values for the IFAT were 100 and 97.7%, respectively. The accuracy (correct classified proportion) for the detection of IgG antibodies against E. cuniculi in cats was 98.8%. The comparison of both serological methods with the PCR results also revealed a good agreement as 20 out of 21 PCR-positive samples were seropositive both in IFAT and WB. Both tests can be considered as equally reliable assays to detect IgG antibodies against E. cuniculi in cats. As the IFAT is quicker and easier to perform, it is recommended for routine use in the diagnosis of feline encephalitozoonosis.

Seroprevalence of Encephalitozoon cuniculi in pet rabbits in Korea

Encephalitozoon cuniculi is a microsporidian parasite commonly found in rabbits that can infect humans, causing encephalitozoonosis. The prevalence of encephalitozoonosis is not well documented, even when many clinics suspect pet rabbits as being highly infected. This study investigated the seropositivity of E. cuniculi using ELISA. The examination of 186 rabbits using ELISA showed that 22.6% (42/186) were seropositive against E. cuniculi. In analysis with healthy status, all 42 seropositive sera were collected from clinically normal rabbits. Moreover, the gender and age of pet rabbits did not have anysignificant effect on E. cuniculi infection. To the best of our knowledge, this is the first report to describe the seroprevalence of E. cuniculi in pet rabbits and suggests that pet rabbits could act as an important reservoir of encephalitozoonosis for both pet animals and humans in Korea.