Deer keds (Diptera: Hippoboscidae) as potential vectors of bacterial and protozoan pathogens in Slovakia

Deer keds are ectoparasitic flies of wild ruminants and are increasingly recognised as potential vectors of various pathogens. This study aimed to assess the prevalence of selected vector-borne pathogens in wingless deer keds collected from 13 red deer and 2 fallow deer, as well as in host-seeking keds across multiple localities in Slovakia. In total, 240 flies identified as Lipoptena spp. were obtained from cervids, and 542 host-seeking deer keds were collected. Individual flies were screened using molecular methods for the presence of Borrelia spp., Bartonella spp., Rickettsia spp., haemotropic Mycoplasma spp., Anaplasma phagocytophilum, piroplasmids, and Kinetoplastida. In wingless Lipoptena spp., high DNA prevalence rates were detected for Bartonella spp. (88.33%), piroplasmids (60.83%), Anaplasma phagocytophilum (24.58%), and Kinetoplastida (20.42%). Haemotropic Mycoplasma spp. DNA was confirmed in 4.56% of flies, while DNA of Borrelia spp. and Rickettsia spp. was not detected. Among host-seeking keds, Bartonella spp. DNA was detected in 7.38%, Rickettsia spp. DNA in 0.92%, and haemotropic Mycoplasma spp. DNA in 0.37%, whereas the remaining pathogens were not detected. Regression analysis indicated significantly greater pathogen-group richness in deer keds collected from cervids, as host-seeking keds harboured an average of 1.76 fewer pathogen types than host-derived individuals. The probability of detecting Bartonella spp. and haemotropic Mycoplasma spp. was markedly lower in host-seeking keds. Overall, this study highlights the epidemiological relevance of Lipoptena spp. and underscores the need for further research on their vector competence and potential implications for animal and public health.