Retrospective analysis of vector-borne infections in dogs after travelling to endemic areas (2007–2018)

Canine vector-borne infections gained in importance in Germany due to growing tourist traffic, the increased import of dogs from abroad and the changing of climatic conditions. The Mediterranean region and southeastern Europe are geographical areas where pathogens such as Leishmania (L.) infantum, Hepatozoon (H.) canis, Ehrlichia (E.) canis, Anaplasma (A.) platys and Dirofilaria (D.) spp. are endemic. Meanwhile, Babesia (B.) spp. and A. phagocytophilum are present in central and western Europe. The objective of this retrospective study was to evaluate whether dogs were exposed to a corresponding risk of infection when travelling to regions in the Mediterranean area and southeastern Europe, which are endemic for these pathogens. Medical records and laboratory test results of 303 dogs that travelled to 14 countries endemic for the mentioned canine vector-borne pathogens and that were presented to the Small Animal Clinic at Freie Universität Berlin between 2007 and 2018 were retrospectively reviewed. A total of 1174 test results from external laboratories were descriptively analysed including 525 test results of direct and 649 of indirect determination methods. Overall, 13% of the tested dogs (40/303) were positive for at least one pathogen. Concurrent infections with two pathogens were detected in 1% of the dogs (4/303). The positive results were: E. canis 8% (18/231 dogs; Polymerase chain reaction [PCR] 3/73, indirect immunofluorescence test [IFAT] 18/209 dogs), L. infantum 5% (14/260 dogs; PCR 5/80, IFAT or enzyme linked immunosorbent assay [ELISA] 11/251 dogs), Babesia spp. 5% (11/232 dogs; Babesia spp. PCR 3/127, B. canis/vogeli IFAT or ELISA 8/160, B. gibsoni IFAT 2/22), Dirofilaria spp. 1% (1/133 dogs; D. immitis antigen-ELISA 1/117, microfilariae PCR 0/16, Knott´s test 0/69 dogs). None of the dogs has been tested positive in a combined Babesia spp./Hepatozoon spp. PCR test (0/15 dogs) and for H. canis (0/17 dogs; PCR) or A. platys (0/11 dogs; PCR). There is a substantial risk for dogs travelling to areas endemic for vector-borne pathogens even with limited time of exposure to get infected. The data indicates the importance of owner education and prophylactic measurements against vector-borne infections in dogs travelling to endemic areas.