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The Prevalence of Encephalitozoon cuniculi in the Domestic Rabbit Population

April Reeves, Kathleen Logan, Karen Snowden

Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, TX, USA


Encephalitozoon cuniculi, an obligate intracellular microsporidia, affects several species of animals, namely rabbits and rodents, causing neurologic disorders, renal failure, and cataracts. This study focused on investigating the prevalence of infection with Encephalitozoon cuniculi in the domestic rabbit population through parasitologic identification and serology.  Sampling for this study consisted of randomly choosing healthy animals used for meat production, breeding, showing, or pets from various rabbitries and obtaining fecal, urine, and blood samples.  Detection methods included using both calcofluor white M2R and modified trichrome blue stains for parasitologic identification of parasite spores in fecal and urine samples as well as identification of seropositive animals using immunofluorescent antibody staining for the presence of anti-E. cuniculi antibodies in blood samples.  Initial results show an overall seroprevalence of .  Spore shedding was detected at a rate of 49.02% in fecal samples stained with calcofluor and 33.33% in samples stained with modified trichrome (n=51).  Urine samples showed a 19.05% rate of spore detection with  both calcofluor and trichrome staining (n=21).  To our knowledge, this is the first time that parasitologic identification of spores in fecal and urine samples has been evaluated in conjunction with serology in rabbit populations.  The unexpectedly high parasitologic and serologic prevalence in asymptomatic domestic rabbits indicate that E. cuniculi is a significant unrecognized  pathogen and should be considered when evaluating an animal patient with neurologic, renal, or ocular disorders.  Due to multiple documented cases of E. cuniculi infection causing a disseminated disease in human HIV-positive patients, caution should be taken to avoid exposure of these individuals to parasite spores.