phaidra.vetmeduni.ac.at o:5577 DOI 10.3390/poultry5020025 Inclusion Body Hepatitis (IBH) Outbreaks Following Vertical Transmission of Fowl Adenovirus Serotype 11 (FAdV-11), Species D: A Strain with Regional Persistence and Global Presence In recent years, outbreaks of inclusion body hepatitis (IBH) have been reported with increasing frequency worldwide. In Austria, the presence of fowl aviadenoviruses (FAdVs) and/or IBH has been documented sporadically. The present report describes a surge of natural IBH cases in fifteen Ross 308 broiler flocks. The clinical picture was characterized by the sudden onset of increased mortality in birds 3 to 15 days of age, persisting for approximately one week, resulting in cumulative flock mortality ranging from 2% to 27%. The main pathological findings were hepatitis with diffuse necrotic foci and petechial hemorrhages with intranuclear inclusion bodies by histology. FAdV was detected in liver samples from all affected flocks. Based upon partial hexon sequence analysis, FAdV serotype-11, species-D (FAdV-11, FAdV-D) was identified, showing complete sequence identity among broiler-derived strains and high identity with previous isolates from Austria and globally IBH-associated isolates. Furthermore, FAdV-11 DNA was detected in dead-in-shell embryos collected during the ongoing outbreak, originating from one suspect broiler breeder flock, confirming vertical transmission. Serological investigations of the suspect breeders confirmed the FAdV-11 infections within the studied timeframe. In conclusion, investigations confirmed vertical transmission of FAdV-11 and subsequent manifestation of IBH in broilers under field conditions, highlighting the epidemiological importance of broiler breeders in IBH outbreaks. eng inclusion body hepatitis fowl adenovirus serotype 11 broiler broiler breeder vertical transmission mortality 2026-10-09T08:18:36.725Z LOMv1.0 Author BEGIN:VCARD VERSION:3.0 N:Grafl;Beatrice; FN:Beatrice Grafl X-ORCID:https://orcid.org/0009-0006-1976-0490 END:VCARD BEGIN:VCARD VERSION:3.0 N:Mitsch;Peter; FN:Peter Mitsch END:VCARD BEGIN:VCARD VERSION:3.0 N:Wiesinger;Ernst; FN:Ernst Wiesinger END:VCARD BEGIN:VCARD VERSION:3.0 N:Ziegerhofer;Josef; FN:Josef Ziegerhofer END:VCARD BEGIN:VCARD VERSION:3.0 N:Bilic;Ivana; FN:Ivana Bilic X-ORCID:https://orcid.org/0000-0003-3296-5117 END:VCARD BEGIN:VCARD VERSION:3.0 N:Hess;Claudia; FN:Claudia Hess X-ORCID:https://orcid.org/0000-0002-3535-5157 END:VCARD BEGIN:VCARD VERSION:3.0 N:Liebhart;Dieter; FN:Dieter Liebhart X-ORCID:https://orcid.org/0000-0003-2412-1248 END:VCARD BEGIN:VCARD VERSION:3.0 N:Hess;Michael; FN:Michael Hess X-ORCID:https://orcid.org/0000-0002-6991-0120 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 3010830 https://phaidra.vetmeduni.ac.at/o:5577 https://phaidra.vetmeduni.ac.at/api/object/o:5577/thumbnail LOMv1.0 discipline