A Review of Encephalitozoon cuniculi in Domestic Rabbits

Domestic rabbits infected with Encephalitozoon cuniculi can be asymptomatic or even show neurological or renal signs of disease. Diagnosis and prevention of parasitic transmission is extremely important because there can be a significant number of asymptomatic carriers. 

Out of all parasitic diseases, this is the most prevalent in this species. The high morbidity and potential zoonotic risk can have economic consequences. The high prevalence of this parasite in rabbit farms is normally a result of poor husbandry practices and inadequate prophylactic measures. The presence of this parasite in younger rabbits is normally a consequence of immature immune systems that can’t fight the parasite.  

The disease can present itself in different ways depending on the host’s immune system. Immunocompromised animals show more severe and potentially fatal signs. The disease can be acute or chronic with the latter being more difficult to observe. The most affected organs are the central nervous system (CNS), the kidneys and eyes. 

Vestibular disease is the most common manifestation of acute disease. Clinical signs can vary from head tilt, ataxia, nystagmus, paresis, tremors and seizures to longitudinal rolling and hindlimb paralysis. Renal insufficiency is a consequence of chronic disease with affected animals presenting with azotemia, weight loss, cystitis, polyuria and polydipsia, amongst other clinical signs. When the parasite invades the ocular lens, rabbits can present with phacoclastic uveitis which is generally unilateral.  

Diagnosis of the disease and choice of the best method for diagnosis has been a challenge over the last decades. The most frequently used diagnostic methods are histopathology, serology and molecular genetic techniques. 

Treatment can be as challenging as diagnosis since there is no cure and acute cases in immunocompromised animals are normally fatal. Frequently used drugs include antiparasitics and those used to treat clinical signs. Treatment of infections normally includes fenbendazole, systemic antibiotics and supportive treatments. Transmission prevention is based mainly in prophylactic administration of fenbendazole, periodic serological testing of rabbit populations and maintaining a clean environment. 

Prognosis is reserved, especially in cases where cerebral and renal lesions are irreversible.   

Doboși, A.-A.; Bel, L.-V.; Paștiu, A.I.; Pusta, D.L. A Review of Encephalitozoon cuniculi in Domestic Rabbits (Oryctolagus cuniculus)—Biology, Clinical Signs, Diagnostic Techniques, Treatment, and Prevention. Pathogens 2022, 11, 1486. https://doi.org/10.3390/pathogens11121486