Zum Vorkommen Transmissibler Spongiformer Enzephalopathien und bakterieller ZNS-Infektionen beim Reh-, Rot- und Gamswild in Bayern

About the occurrence of Transmissible Spongiform Encephalopathies
and bacterial CNS infections in roe deer, red deer and chamois in
Bavaria Brain samples of 849 wild ruminants (654 roe deer, 189 red
deer and 6 chamois) from Bavaria were examined for the occurrence
of TSE and encephalopathies caused by bacteria, respectively. For
this, the following investigations were carried out: • General
bacteriological investigation (aerobic incubation on blood,
standard I nutrient and Gassner Agar) • Detection of Listeria spp.
by selective procedures - Cultural isolation and biochemical
identification with the BBL crystal ID system - Detection of the
iap gene using real time PCR (Lightcycler) • Detection of PrPres by
ELISA technique (BioRad) • Histological investigation - HE staining
- Immunohistochemistry (mAb L42) Using conventional bacteriological
methods, 464 different bacteria were isolated. 229 of them could be
differentiated at the genus level and 235 at the species level.
Totally, 35 different bacteria species were isolated, most
frequently Micrococcus spp., Bacillus spp. and E. coli. Listeria
spp. were detected in 55 brain samples (49 from roe deer, 5 from
red deer and 1 from chamois). 52 isolates were identified with the
BBL crystal ID system as Listeria monocytogenes and 3 as Listeria
grayi ssp. murrayi. As the iap gene was detected in all strains,
the correctness of the BBL result concerning L. grayi ssp. murrayi
must be scrutinised. Analysis of the geographical distribution of
the Listeria findings indicate a regional aggregation in
Unterfranken (prevalence for roe deer: 17,8 %, versus 6,6 % in
Oberbayern-Schwaben, 6,1 in Niederbayern-Oberpfalz and 0 % in
Oberfranken-Mittelfranken). The histological investigation (HE
staining) of 87 tissue samples contaminated with encephalitis
relevant bacteria showed inflammation of different severity (e. g.
perivascular infiltration (n = 26) or (meningo)encephalitis (n =
13)) in 41 cases. The validation of the ELISA technique for
detecting prionprotein from wild ruminants pointed out that the
examination of brain of wild ruminants lead to lower extinctions
than that of bovine brain samples. Due to the fact that brain
homogenate of 2 known CWD positive wapitis showed definite positive
results, all samples were analysed with this test: There were no
indications for the occurrence of TSE in any sample. In addition,
immunohistochemical investigations of 10 % of all samples did not
show PrPres. Due to the large number of samples, the prevalence of
TSE can be quoted under 0,5 % for roe deer and under 1,5 % for red
deer with a certainty of 95 %.