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.