Investigation of avian louse flies as potential vectors of protozoan and bacterial pathogens of veterinary importance

Avian louse flies (Hippoboscidae: Ornithomyinae) are blood-feeding parasites with largely unexplored vector potential, although they have been implicated in the transmission of pathogens of medical and veterinary relevance, such as West-Nile virus, Babesia and Trypanosoma species. We screened 253 specimens of nine Ornithomyinae species for selected bacteria (Anaplasma, Rickettsia, Bartonella, Borrelia, and Ehrlichia spp.) as well as for trypanosomes and piroplasms. Anaplasma phagocytophilum was detected in a single Ornithomya avicularia specimen, and Haematospirillum jordaniae was identified in three Ornithomya fringillina individuals from the same location, representing the first report of these bacteria in avian louse flies. In addition, eight different Trypanosoma sequences were obtained, belonging to the T. corvi/culicavium and T. bennetti groups. Unexpectedly, a sequence resembling T. theileri was recovered from an Ornithoica turdi specimen. Our findings suggest that the role of louse flies in transmitting the investigated bacterial pathogens is likely minimal, but their involvement in the ecology of Trypanosoma species warrants further study. Consistent with previous work, we propose that louse flies could serve as valuable sentinels for monitoring pathogens in wild bird populations.