Retrospective Analysis of Canine Vector-borne Diseases (CVBD) in Germany with Emphasis on the Endemicity and Risk Factors of Leishmaniosis

A cross-sectional study was designed to provide data on the detection of canine vector-borne diseases (CVBDs) with special emphasis on leishmaniosis in Germany. For this purpose, results of blood or serum samples sent by local veterinarians to a veterinary diagnostic laboratory were retrospectively analysed. Samples were examined for Leishmania spp., Babesia spp., Ehrlichia canis, Dirofilaria immitis and Anaplasma phagocytophilum during the years 2004-2006 and 2014-2016 (Leishmania only). Erythrocyte stages of large Babesia spp. or Babesia DNA were found in 1.7 % of 9,966 blood smears and 3.3 % of 15,555 samples examined by PCR, respectively. Large Babesia merozoites were found more frequently in Giemsa-stained smears from dogs born in Germany when compared to blood samples of dogs originating from south or south-east European countries. A total of 15 blood samples of German dogs which have never been abroad were positive for Babesia DNA. Antibodies titres (>=80) against Babesia canis were detected by IFAT in 11.5 % of 2,653 serum samples. Out of 570 samples 3.2 % were positive for E. canis using PCR. Antibodies against E. canis and A. phagocytophilum (both at titres >=50) were detected by indirect IFAT in 15.1 % and 41.9 % of 18,652 and 794 serum samples, respectively. Using Knott's test 4.5 % of 440 blood samples were positive for microfilariae, and Dirofilaria immitis antigen was found by ELISA in 1.4 % of 9,381 serum samples. Leishmania spp. DNA was detected in 11 % of 301 whole blood or tissue samples examined by PCR. Antibodies against Leishmania were found in 23.5 % (23,665 samples) and 22.7 % (54,103 samples) of blood samples by IFAT (titres >=50) and ELISA (>=7 test units), respectively (2004-2006 versus 2014-2016). Antibodies against Leishmania (IFAT) were detected in 80.6 % (399/495) of dogs imported from endemic areas, in 57.6 % (34/59) of German dogs travelling outside Germany and in 4 (n = 8) German dogs without any history of travelling. Potential endemicity of leishmaniosis in Southern Germany was prospectively evaluated. For some of these infectious agents, sex or age of dogs and season were identified as risk factors.