phaidra.vetmeduni.ac.at o:2103 DOI 10.3390/ani12172212 Exo-Erythrocytic Development of Avian Haemosporidian Parasites in European Owls Avian haemosporidian parasites (Haemosporida, Apicomplexa) are globally distributed and infect birds of many orders. These pathogens have been much investigated in domestic and wild passeriform birds, in which they are relatively easy to access. In birds belonging to other orders, including owls (order Strigiformes), these parasites have been studied fragmentarily. Particularly little is known about the exo-erythrocytic development of avian haemosporidians. The goal of this study was to gain new knowledge about the parasites infecting owls in Europe and investigate their exo-erythrocytic stages. Tissue samples of 121 deceased owls were collected in Austria and Lithuania, and examined using polymerase chain reactions (PCR), histology, and chromogenic in situ hybridization (CISH). PCR-based diagnostics showed a total prevalence of 73.6%, revealing two previously unreported Haemoproteus and five novel Leucocytozoon lineages. By CISH and histology, meronts of several Leucocytozoon lineages (lASOT06, lSTAL5, lSTAL7) were discovered in the brains, heart muscles, and kidneys of infected birds. Further, megalomeronts of Haemoproteus syrnii (lineage hSTAL2) were discovered. This study contributes new knowledge to a better understanding of the biodiversity of avian haemosporidian parasites infecting owls in Europe, provides information on tissue stages of the parasites, and calls for further research of these under-investigated pathogens relevant to bird health. eng Blood Parasites; Molecular Characterization; Leucocytozoon-Ziemanni; Malaria Parasites; Haemoproteus; Hematozoa; Plasmodium; Infection; Prevalence; Diversity 2023-09-18T14:18:44.518Z LOMv1.0 Author BEGIN:VCARD VERSION:3.0 N:Ilgūnas;Mikas; FN:Mikas Ilgūnas END:VCARD BEGIN:VCARD VERSION:3.0 N:Weissenböck;Herbert; FN:Herbert Weissenböck X-ORCID:https://orcid.org/0000-0001-8197-6379 END:VCARD BEGIN:VCARD VERSION:3.0 N:Valkiūnas;Gediminas; FN:Gediminas Valkiūnas END:VCARD BEGIN:VCARD VERSION:3.0 N:Dagys;Mindaugas; FN:Mindaugas Dagys END:VCARD BEGIN:VCARD VERSION:3.0 N:Himmel;Tanja; FN:Tanja Himmel X-ORCID:https://orcid.org/0000-0001-9443-8967 END:VCARD BEGIN:VCARD VERSION:3.0 N:Harl;Josef; FN:Josef Harl X-ORCID:https://orcid.org/0000-0002-4915-3943 END:VCARD https://w3id.org/kim/hcrt/scheme https://w3id.org/kim/hcrt/text Textdokument Text LOMv1.0 yes https://creativecommons.org/licenses/by/4.0 application/pdf 974389 https://phaidra.vetmeduni.ac.at/o:2103 https://phaidra.vetmeduni.ac.at/api/object/o:2103/thumbnail LOMv1.0 discipline