Leishmania and phlebovirus seroprevalence in dogs in two non-endemic central European countries: Austria and Germany.

In Mediterranean Europe, human and canine leishmanioses, mainly caused by the sand fly-borne protozoan parasite Leishmania infantum, are highly endemic, and Phlebovirus infections are common. Dogs represent the main reservoir hosts of L. infantum, facilitating zoonotic vector-borne circulation. Although phleboviruses are primarily of medical importance in humans, dogs are regularly exposed due to the overlapping ecology of Leishmania and phleboviruses and serve as good sentinels for circulation. This study aimed to assess canine Leishmania and phlebovirus seroprevalence in two understudied non-endemic Central European countries, Austria and Germany. 1520 dog sera from Austria (n = 760) and Germany (n = 760) were screened for anti-Leishmania antibodies by immunofluorescence antibody tests (IFAT) and for anti-phlebovirus antibodies using seroneutralization assays. For positive tested dogs of Austrian or German origin without travel history, clinical, anamnestic data, and, if available, PCR-based confirmation was assessed. Leishmania seroprevalence was 0.8% (95% CI: 0.3-1.7%) in Austrian and 1.2% (95% CI: 0.5-2.2%) in German dogs. Phlebovirus seroprevalence was 1.7% (95% CI: 0.9-2.9%) and 2.9% (95% CI: 1.8-4.4%) in these study populations, respectively. No statistically significant difference in seropositivity for both agents was observed between dogs living in sand fly endemic versus non-endemic regions. While most Leishmania-seropositive dogs had been imported from Leishmania-endemic countries, three had been born in Austria or Germany and had never travelled to endemic regions. Our study highlights that seropositive dogs living in non-endemic countries are mainly imported from endemic regions. Nevertheless, few potential local transmission events highlight the complexity of sand fly-borne disease epidemiology and require broader surveillance programs.