Renal abscess in a Lionhead rabbit due to Encephalitozoon cuniculi and Escherichia coli: A case report.

Background: In rabbits, renal abscesses (pus-filled sores) are rare and diagnosis remains challenging. Therefore, in this study, we aimed to determine the clinical manifestation and diagnostic tests associated with renal abscess identification in rabbits. Case Description: A four-and-a-half-year-old castrated male Lionhead rabbit with a history of poor appetite and abdominal distension was admitted to the animal hospital. Blood analysis, radiography, ultrasonography, and computed tomography scans revealed a kidney abscess found within the renal parenchyma, with severe loss of the cortex and medulla, extending toward the capsule. Consequently, the rabbit underwent nephrectomy. The enlarged right kidney was surgically removed. Histopathological examination of the affected kidney showed severe necrosis and ischemic zones, atrophy of the renal tubules, and prominent heterophils with mixed inflammatory cell infiltrates. Immunohistochemistry and polymerase chain reaction confirmed Encephalitozoon cuniculi and Escherichia coli infections, respectively. Conclusion: This report provides novel insights into the diagnosis of renal abscesses in Lionhead rabbits.

Clinicopathologic findings and causes of mortality in 100 pet rabbits from the Canary Islands, Spain, 2011-2022.

The European domestic rabbit (Oryctolagus cuniculus domesticus) is commonly kept as a pet, with increasing popularity among pet owners. Despite the increasing body of information on lagomorph medicine and pathology, comprehensive published compilations of causes of mortality in pet rabbits are limited. We analyzed health disorders, pathology findings, and most probable causes of death in 100 pet rabbits submitted to the Anatomopathological Diagnostic Service of the Veterinary School of the University of Las Palmas de Gran Canaria, Canary Islands, Spain, from 2011 to 2022. We reviewed clinical data and gross and histopathologic findings to classify the various disorders into infectious (n = 39), noninfectious (n = 45), and idiopathic conditions (n = 16). Within infectious disease processes, Encephalitozoon cuniculi infection (n = 14) and rabbit hemorrhagic viral disease (n = 14) had the highest prevalence. Regarding the noninfectious conditions, perioperative mortality (n = 10), gastrointestinal syndrome (n = 7), and trauma (n = 6) were the most common clinicopathologic entities observed.

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

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

Prevalence of Encephalitozoon hellem among companion and exhibition birds in Japan.

Microsporidia can cause infection in various animals and humans. To determine the recent prevalence of Encephalitozoon in companion birds in Japan, 364 bird feces and 16 conjunctival exudates, as well as 28 exhibition bird feces, were examined using polymerase chain reaction (PCR). Thirty-five (9.6%) feces and 2 (12.5%) conjunctival exudates from companion birds were PCR positive, and sequence analysis revealed that all detected organisms were Encephalitozoon hellem genotype 1A. The prevalence by region varied from 4.5% in the Shikoku region to 14.3% in the Chugoku region. By age, the prevalence in birds younger than 6 months of age was 13.3%. We also discuss the threat of human infection as a zoonotic disease.

Otitis media/interna and encephalitozoonosis are the most common causes of head tilt in pet rabbits in the UK: 73 cases (2009‒2020).

BACKGROUND: There are limited studies that identify diseases associated with head tilt in pet rabbits. METHODS: This was an observational, retrospective, single-centre study of rabbits with head tilt presented between 2009 and 2020. Descriptive statistics were performed for all cases, whereas univariate and multivariate analyses were only performed for the 36 cases with a final diagnosis. RESULTS: Seventy-three rabbits met the inclusion criteria. The final diagnoses included Encephalitozoon cuniculi meningoencephalomyelitis (EC) (15/36; 41.7%), otitis media/interna (OMI) (8/36; 22.2%) and concurrent EC and OMI (13/38; 36.1%). Subacute-to-chronic onset was more common in rabbits with OMI than in those with EC (p = 0.018). Previous middle ear surgery (p = 0.046) and a diagnosis of otitis externa (p = 0.004) significantly increased the risk of OMI. Meloxicam was associated with improvement of clinical signs (p = 0.007). Upright ears (p = 0.013), recumbency (p = 0.037) and impaired mentation (p = 0.001) were associated with a higher risk of death/euthanasia. The proportions of residual head tilt (66.7%) and relapse of vestibular signs (42.1%) were high. LIMITATIONS: This was a retrospective study with cases varying in their investigation and conclusive final diagnoses. CONCLUSION: OMI and EC were the most common aetiologies of head tilt in pet rabbits in the UK. Meloxicam might be associated with a favourable outcome in affected rabbits. Paired EC serology and a CT scan of the head should be the baseline investigation for head tilt in rabbits.

Renal pathology in wild European rabbits.

BACKGROUND: There is a relative paucity of data examining the prevalence of renal pathology in wild rabbits. METHODS: Sixty-two wild rabbits that had been shot for population control in Cambridgeshire, UK, underwent postmortem examination, including macroscopic and microscopic renal assessment. RESULTS: The majority (82%) of the animals had macroscopically and microscopically normal kidneys. One animal (1.6%) had severe perirenal abscessation. Pasteurella spp. was isolated from this lesion. Ten rabbits (16%) had microscopic renal pathology comprising minimal to mild renal inflammation or fibrosis. No Encephalitozoon cuniculi organisms were detected histologically. LIMITATIONS: The sample population was composed of shot rabbits, so the probability of detecting moribund individuals was reduced. Extrapolation of these data to the wider UK wild rabbit population may be limited as rabbits were shot at two sites within a 3 km radius of each other. CONCLUSION: Renal pathology is rare in the population examined.

[Ophthalmic findings caused by Encephalitozoon cuniculi (strain III) in a dog]. / Ophthalmologische Befunde durch Enzephalitozoon cuniculi (Stamm III) bei einem Hund.

A 2-year-old female mixed-breed canine patient from Namibia presented originally with chronic uveitis. A serum antibody titer and a PCR test performed on the aqueous humor were positive for encephalitozoon cuniculi. The left eye showed an immature anterior focal cortical cataract in the periphery with suspected lens capsule rupture and signs of chronic uveitis. An incipient anterior focal cortical cataract was also perceivable in the patient's right eye. Despite local treatment as well as systemic administration of carprofen, prednisolone, and fenbendazol recurrent uveitis occurred. The patient then underwent bilateral extracapsular lensextraction via phacoemulsification. A PCR test of the lens material was positive for encephalitozoon cuniculi strain III. Recurring uveitis and secondary glaucoma 10 months post-op resulted in permanent blindness of the left eye. The patient then continued to receive local anti-inflammatory treatment. The last recheck examination of both eyes, 31 month post-op, revealed no signs of uveitis. This is the first case reported of a cataract in a canine patient caused by encephalitozoon cuniculi strain III.

Distribution of M1 and M2 macrophages in cerebral granulomas caused by Encephalitozoon cuniculi.

Encephalitozoon cuniculi spores cause severe granulomatous inflammation in the brain where mononuclear cells and macrophages infiltrate. Here, we orally infected New Zealand white rabbits with 1 × 106E. cuniculi viable spores to study the recruitment and localization of macrophages in brain granulomas. At day 30 post-infection, the positive phenotype markers iNOS (M1) and Arg-1 (M2) were located in the periphery and center of granulomas, respectively. Live intracytoplasmic spores were found only in positive Arg-1 cells. This is the first work to describe the recruitment and distribution of M1 and M2 macrophages in the brain granulomas of rabbits infected with E. cuniculi.

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.

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.

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.

Encephalitozoon cuniculi and Extraintestinal Microsporidiosis in Bird Owners.

We identified Encephalitozoon cuniculi genotype II parasites as a cause of extraintestinal microsporidiosis in 2 owners of birds also infected with E. cuniculi. Patients experienced long-lasting nonspecific symptoms; the disease course was more progressive in a patient with diabetes. Our findings suggest direct bird-to-human transmission of this pathogen.

Mice with genetic and induced B-cell deficiency as a model for disseminated encephalitozoonosis.

Encephalitozoon cuniculi, an intracellular pathogen, lives in a balanced relationship with immunocompetent individuals based on the activity of T lymphocytes. We previously highlighted the greater susceptibility of B-1 cell-deficient mice (XID mice) to encephalitozoonosis. This study aimed to develop a model of disseminated and severe encephalitozoonosis in mice with combined immunodeficiency to elucidate the role of B cells. To address this objective, cyclophosphamide (Cy)-treated BALB/c and XID mice were inoculated with E. cuniculi, followed by the evaluation of the immune response and histopathological lesions. Immunosuppressed BALB/c mice manifested no clinical signs with an increase in the populations of T lymphocytes and macrophages in the spleen. Immunosuppressed and infected XID mice revealed elevated T cells, macrophages populations, and pro-inflammatory cytokines levels (IFN-γ, TNF-α, and IL-6) with the presence of abdominal effusion and lesions in multiple organs. These clinical characteristics are associated with extensive and severe encephalitozoonosis. The symptoms and lesion size were reduced, whereas B-2 and CD4+ T cells populations were increased in the spleen by transferring B-2 cells adoptive to XID mice. Moreover, B-1 cells adoptive transfer upregulated the peritoneal populations of B-2 cells and macrophages but not T lymphocytes and decreased the symptoms. Herein, we speculated the consistency in the development of severe and disseminated encephalitozoonosis in mice with genetic deficiency of Bruton's tyrosine kinase (Btk) associated with Cy immunosuppression develop with that of the models with T cell deficiency. Taken together, these data emphasized the crucial role of B cells in the protective immune response against encephalitozoonosis.

Molecular detection and genotype identification of E. cuniculi from pet rabbits.

Encephalitozoon cuniculi is a microsporidian which is frequently reported from rabbits. This microorganism can either ravage rabbit farms or transmit to humans from pet rabbits. This study aimed to investigate the prevalence and the genotype distribution of E. cuniculi among pet rabbits. In this study urine samples were collected from 50 pet rabbits, aged 2 months to 3 years, admitted to teaching veterinary hospital. Four races Lop, Dutch, Mix, and Angora were screened for E. cuniculi. The clinical symptoms were recorded and total DNA was extracted from urine samples. E. cuniculi was identified using amplification of the small subunit ribosomal RNA (ssu rRNA) gene and its genotypes were characterized using PCR/sequencing of the polar tube protein (PTP) gene. Phylogenetic tree was drawn to confirm the characterized genotypes. Out of 50 samples, 41 (82 %) of rabbits were asymptomatic, while nine (18 %) had at least one of symptoms including head-tilt, circling, and ataxia. A statistical correlation was seen between mean age + SD and symptoms (P-value = 0.039). The presence of E. cuniculi was confirmed in 16/50 (32 %) rabbits and all of them were identified as the genotype I. Our findings represented no consistency between E. cuniculi PCR - positive and the presence of symptoms (P-value = 0.318). Our results showed positive correlation between symptoms and age; however, the lack of correlation between PCR results with age may signify the latent infection in younger rabbits. All identified E. cuniculi were the genotype I, which is reported from rabbits and humans, highlighting the zoonotic concern for this genotype, particularly among subjects who keep pet rabbits.

Isolation of Streptococcus cuniculi from corneal lesion in laboratory-raised mice.

Corneal lesions appearing as white mass beneath intact epithelium, with ocular discharge in one mouse, was observed in a batch of laboratory-raised BALB/c mice (n=9 of 56). The affected mice remained active, well-groomed and had normal appetite. Isolates recovered from swab cultures of the external and internal contents of the eye had partial 16S rRNA gene sequence of 99.1% similarity to Streptococcus cuniculi. No previous report of S. cuniculi infection in laboratory rodents has been presented. The isolate was susceptible to all antibiotics tested. We suggest S. cuniculi is an opportunistic bacteria in laboratory mice but are uncertain of its source. Our findings revealed that S. cuniculi is able to colonize laboratory mice and should be considered when mice present with eye lesion or ocular discharge.

Encephalitozoon cuniculi infection in cats: European guidelines from the ABCD on prevention and management.

OVERVIEW: Encephalitozoon cuniculi is a common obligate intracellular microsporidian parasite of rabbits that is increasingly recognised as a pathogen of cats and other mammalian species. These guidelines aim to review the literature on feline E cuniculi infection and provide recommendations on prevention and management. INFECTION IN CATS: E cuniculi infection should be considered as a differential diagnosis in cases of feline uveitis and cataract formation. It is not significantly associated with either chronic kidney disease or meningoencephalitis. E cuniculi infection is more common in stray or feral cats than in pet cats. DIAGNOSIS AND TREATMENT: Serological tests for antibody detection in the blood are easy to perform and can be useful for diagnosis, but their specificity is low as antibodies have been found in apparently healthy cats. PCR appears to be more sensitive than histopathology for diagnosis, and is more sensitive when performed on cataractous lenses compared with aqueous humour, although ease of sampling is an obvious limitation. Treatment is with fenbendazole for 3 weeks and phacoemulsification to remove microsporidia from cataractous lenses. ZOONOTIC RISK: E cuniculi is a potential zoonotic agent, and there is a particular risk to immunocompromised humans posed by infected rabbits. Albeit infrequent, spore shedding has been identified in cats, so care should be taken around infected cats.

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.

Encephalitozoon cuniculi infection in farmed rabbits in Egypt.

BACKGROUND: Encephalitozoon cuniculi is an important microsporidian parasite with zoonotic potential. The present study highlights the impact of encephalitozoonosis on rabbit health in Egypt. Three rabbit farms in Giza, with a total of 16,400 rabbits were investigated due to occurrence of rabbits displaying clinical signs consistent with encephalitozoonosis. RESULTS: Clinical signs observed during a 4 months observation period in 2018 included vestibular disease, paresis, limb paralysis, cataracts, phacoclastic uveitis, frequent urination, marked decrease in body weight and in some pregnant females, also repeated abortions. The total morbidity rates in adult and young rabbits were 76.7% and 81.5%, respectively. The highest mortality rate was recorded in offspring (12.3%), followed by dams (5.6%), and the lowest recorded mortality rate was in males (0.04%). Post-mortem findings included enteritis, pale enlarged kidneys, congested leptomeninges, focal brain necrosis, and endometrial congestion. Histopathological examination revealed nonsuppurative meningoencephalitis and glial nodules with central necrosis in the brain, vacuolation and necrosis of renal tubular epithelium, and corneal ulceration and ruptured lens capsule with fragmentation of lenticular fibres. E. cuniculi were observed in the brain, retinal ganglion cells, kidneys, and liver. Transmission electron microscopy examination revealed the presence of different developmental stages of E. cuniculi in the brain and kidney. Presence of E. cuniculi was confirmed by conventional polymerase chain reaction using a universal 16S gene for Encephalitozoon spp. followed by sequencing and sequence analysis. CONCLUSIONS: The presence of E. cuniculi in rabbits was confirmed at three farms in Egypt. Nervous signs and ocular lesions were the most predominant findings in these farms.

ENCEPHALITOZOON CUNICULI INFECTION IN A BLACK-FOOTED FERRET (MUSTELA NIGRIPES) KIT.

A 47-day-old black-footed ferret (Mustela nigripes) kit was found dead in June 2016. Histologic examination revealed pyogranulomatous tubulointerstitial nephritis, pneumonia, and encephalitis, with intralesional microsporidia. Transmission electron microscopic examination showed microsporidia with ultrastructural characteristics consistent with Encephalitozoon spp. Polymerase chain reaction (PCR) and direct sequencing confirmed the presence of Encephalitozoon cuniculi genotype II. This organism has been reported in other Carnivora (i.e., canids, felids, mustelids, procyonids, otariids). In humans, it is generally described as an opportunistic pathogen in immunocompromised individuals. The source of infection in the quarantine facility remains unknown, although two groups of frozen feeder rat kidneys tested positive for E. cuniculi genotype II via PCR. Feeding whole prey to various zoo taxa carries some potential disease transmission risk.