Molecular Survey of Hemosporidian Parasites in Owls in Mainland Portugal.

Owls play an important role as avian hosts for hemosporidians via overlap in habitat use and activity with these arthropod vectors, thereby resulting in susceptibility to morbidity and, in some cases, mortality upon infection. This study analyzed the hemosporidians in tissues collected from individual dead owls (n=240) in various regions of mainland Portugal; the owls were primarily obtained from wildlife rehabilitation centers (WRCs). Hemosporidian species were detected using nested PCRs, targeting the cytochrome b gene of the mitochondria. For species and lineage identification, 19 positive PCR samples were selected and sequenced by the Sanger method. In total, 51% (n=122) of the 240 owl samples tested positive for at least one hemosporidian species: 31% (n=75) were positive for Haemoproteus-Plasmodium spp., whereas 44% (n=106) were positive for Leucocytozoon spp. Only 7% (n=16) were positive for Haemoproteus-Plasmodium spp. alone and 20% (n=47) for Leucocytozoon spp. alone, whereas 25% (n=59) of owls had mixed infections. Owl species, age, and geographic region of collected samples were significantly associated with hemosporidian prevalence: Eurasian Eagle-Owls (Bubo bubo), adults, and individuals from the Alentejo region presented higher prevalences than other species, ages, and geographic regions. Our findings highlight the potential impact of hemosporidians on owl conservation, particularly their effect on species currently threatened with extinction and the possible repercussions on reintroduction or translocation projects. This study emphasizes the role of WRCs in disease surveillance and suggests the importance of considering prophylactic measures in these settings. Given the high prevalence of hemosporidians, further studies involving live owls, both wild and captive, are encouraged, along with integrating clinical and hematologic data.