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

The Prevalence of Encephalitozoon cuniculi in Domestic Rabbits (Oryctolagus cuniculus) in the North-Western Region of Romania Using Serological Diagnosis: A Preliminary Study

Encephalitozoon cuniculi is a microsporidian, domestic rabbits being the main host. The disease can be acute or subclinical, but treatment options are limited and usually with unrewarding results; therefore, diagnosis and prevention of encephalitozoonosis in rabbits are of the utmost importance. This study aims to obtain the first preliminary information of the prevalence of E. cuniculi in the north-western region of Romania. A total of 176 rabbits were clinically examined and 2 mL of blood was sampled from each. An enzyme-linked immunosorbent assay (ELISA) kit by Medicago (Medicago, Uppsala, Sweden) on the resulted blood serum was utilized. Statistical analysis of the results was conducted using the EpiInfo 2000 software (CDC, Atlanta, GA, USA). A total prevalence of 39.2% (69/176) was identified, with statistically significant differences in relation to the rabbits' clinical status, age, season of sampling, breeding system, body condition score and county of origin; the different family farms tested also had a statistically significant difference. This study gives the first preliminary information on this pathogen distribution on Romania's territory, but further studies need to be performed on larger regions to declare the prevalence in the country.

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.

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.

A Review of Encephalitozoon cuniculi in Domestic Rabbits (Oryctolagus cuniculus)-Biology, Clinical Signs, Diagnostic Techniques, Treatment, and Prevention

Encephalitozoon cuniculi is a eukaryote, unicellular, spore-forming, obligate intracellular microorganism of the phylum Microsporidia, with domestic rabbits as its main host. Another important species in which this pathogen has been identified are humans, the infection being therefore called a "zoonosis". The transmission takes place via the horizontal route or the vertical route, and cell-mediated immunity plays the biggest role in the infected hosts' protection. Encephalitozoonosis can manifest itself as an acute infection, with neurological signs, renal signs, and ocular lesions, or as a chronic or subclinical infection, which is usually the case for asymptomatic carriers. The diagnostic techniques usually carried out are histological examination, serological tests, and molecular genetic techniques. The treatment of encephalitozoonosis is usually symptomatic, with unrewarding results, and prevention methods include periodical serological screening, prophylactic administration of fenbendazole, and maintenance of a clean environment. The purpose of this article is to review the current data regarding the pathogenesis, host immunity, clinical signs, diagnostic methods, treatment, and prevention methods of encephalitozoonosis in the domestic rabbit, as well as to analyze the prevalence of this disease in different countries of the world.

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.