Encephalitozoonosis in Pet Rabbits: Epidemiology, Pathogenesis, Immunology and Consensus on Clinical Management

Members of the microsporidial genus <i>Encephalitozoon</i> have the capacity to infect both mammals and birds, and <i>E. cuniculi</i> is most commonly found in rabbits. With a seroprevalence ranging up to 85%, <i>E. cuniculi</i> can be a problem in pet rabbits as well as in food production and laboratory animal science. While most infections are likely subclinical, there are three main clinical presentations: neurological, renal, and ocular. Typical clinical signs including vestibular disease and phacoclastic uveitis may develop with initial or relapsing infection, while renal infection is usually progressive and associated with non-specific clinical signs. High-sensitivity/specificity ante mortem diagnostic options are lacking, and serological testing most often provides adjunct rather than definitive information such that physical examination and other diagnostics are used more so for ruling out other differentials and comorbidities, rather than confirming infection. In the veterinary community, treatment regimens are variable given the lack of thorough studies and a consensus. The aim of this document is to present the available literature to give a concise review of this organism and its infection of rabbits as well as to propose guidelines and protocols for diagnostics and treatment regimens. In addition, the current challenges and recommendations for further studies are discussed.