In the present study the application of different diagnostic markers for intram vitam and post mortem diagnosis of E. cuniculi infections in 71 pet rabbits were compared. The examined population was divided into 33 rabbits with symptoms of suspected encephalitozoonosis (neurological symptoms, elevated blood creatinine, or signs of phacoclastic uveitis; group I) and 38 animals without symptoms (group II) which died or were euthanised for unrelated reasons. All animals were examined by Indirect Immunofluorescence Test, histological examination including special spore staining (Ziehl-Neelsen, acid-fast trichrome) and conventional and nested PCR (organs, body fluids).
Additionally, eye lens material of eight seropositive live patients with phacoclastic uveitis was examined by conventional PCR. In group I 69.7 % and in group II 50.0 % showed seroconversion. No difference concerning the titre levels (low, moderate, high) was noticeable between rabbits with suspected encephalitozoonosis and unsuspected rabbits ([chi]2 =0.237; p = 0.627). 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. 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/or histological changes in the brain and/or kidneys) and nested PCR could be detected in 52.1 % of the rabbits (n = 71), whereas 31.0 % showed negative results in all three diagnostic techniques. 5.6 % of the rabbits were positive by two and 11.3 % by one method. Of the 37 rabbits positive in the nested PCR 91.9 % were positive in the brain and 54.1 % in the kidneys. Furthermore nested PCR of urine revealed positive results in 29.7 % of 37 rabbits with seroconversion and/or confirmed E. cuniculi infection by spore detection. All 25 samples of CSF tested negative in nested PCR.
The post mortem examination of organs by nested PCR showed that the brain was the most appropriate tissue for the detection of E. cuniculi DNA. Moreover the distribution and extent of histological lesions in the brain and in the kidney of natural infected pet rabbits with or without clinical encephalitozoonosis was determined. In the brain the cerebrum (97.5 %) and the brain stem (77.5 %) were the most frequently affected regions. The cerebellum (55 %) and the vestibular cores (37.5 %) were less commonly concerned. Granulomas were found in 77.5 % of animals with non-suppurative encephalitis and in 12.5 % of rabbits with interstitial nephritis. Granulomas were found in the brain in all grades (from discret to severe). However the more pronounced histological lesions were the higher was the probatility to find granulomas. There was no correlation between the severity of encephalitis and the occurrence of neurological symptoms. Since severe lesions were also found in clinically inconspicuous animals, histological findings of inflammatory lesions are not indicative of overt encephalitozoonosis as the causative agent for neurological signs.