Diagnostic markers for encephalitozoonosis in pet rabbits

Encephalitozoonosis is a common disease in pet rabbits, routinely diagnosed in vivo by serological examination or post mortem by histopathology. Recently molecular techniques have become increasingly important as diagnostic tools. The application of different diagnostic markers for in vivo and post mortem determination of E. cuniculi in naturally infected pet rabbits were compared. The examined population was divided into 33 rabbits with symptoms of encephalitozoonosis (group I) and 38 animals without symptoms (group II) which were all tested by serological analysis (Indirect Immunofluorescence Test), histological examination including special spore staining (Ziehl-Neelsen, acid-fast trichrome) and conventional and nested PCR (organs, body fluids). Additionally, in group III lens material (n=10) of animals (n=9) with phacoclastic uveitis were examined by conventional PCR. Infections with E. cuniculi could be determined post mortem in 78.8% of the rabbits of group I and in 57.9% of group II by histological examination combined with spore staining. In group I 69.7% and in group II 50.0% showed seroconversion. Conventional PCR was only sufficiently sensitive in samples of eyes with phacoclastic uveitis (n=10; 100%). Therefore nested PCR was performed in tissue samples, urine and cerebrospinal fluid (CSF) with positive results in 63.6% of group I and 42.1% of group II. Positive results in serology, pathohistology (spore detection and histological changes in the brain and/or kidneys) and nested PCR were obtained in 52.1% of the rabbits (group I and II, n=71), whereas 31.0% showed negative results in all three diagnostic techniques. 5.6% of the rabbits were positive in two methods and 11.3% in one method. In 37 rabbits (group I and II) with positive results in nested PCR, E. cuniculi DNA could be detected more frequently in the brain (91.9%) than in the kidney (54.1%). Furthermore nested PCR of urine revealed positive results in 29.7% of the rabbits (n=37) with seroconversion and/or confirmed E. cuniculi infection by spore detection. All 25 samples of CSF tested negative in nested PCR. Conventional PCR of eyes with phacoclastic uveitis was an excellent diagnostic marker in living rabbits, while nested PCR of urine or CSF was not reliable. Histological examination combined with special staining was the most sensitive method in post mortem diagnostics. Nested PCR appears to be a good post mortem method to investigate organs, especially brains, of chronically infected animals.