Avian influenza wildlife surveillance in Ukraine – a bridge between Europe and Asia

Introduction. Avian influenza virus (AIV) remains one of the most unpredictable, dangerous pathogens causing disease for humans, animals, birds. Recent spillover of AIV to new hosts emphasizes the importance of expanding the active surveillance and ecological studies in natural hosts. Methods. In total, 41,306 samples (137 wild bird species) in Ukraine in 2009-2024 were tested for presence AIV. Additionally, in 2021-2023, 1722 serum samples, 286 fecal samples from mammals were tested. Results. In total, 207 AIV were isolated from wild birds including 15 HA subtypes and 7 NA serotypes. Most isolates were from waterfowl: Anseriformes (196 AIV, 0.18-2.5%); less from shorebirds: Charadriiformes (17 AIV, 0.12-1.49%); single isolates from Ciconiiformes (6,25%), Pelecaniformes (0.15%). Most viruses were LPAI, but 19 were HPAI, including in clinically healthy waterfowl migratory birds. Genetic analysis revealed a large genetic diversity, phylogenetic association with AIVs reported from Europe, Siberia, Asia. Circulation of influenza viruses (IV), including AIV, in mammals in Ukraine is still open question. However, seropositivity to IV was detected in carnivores (4.2-14.8%). Also, several PCR-positive samples were detected in bats. Conclusions. Our results highlighting the importance of Ukraine for study the ecology of influenza. The finding of AIV, connectivity of Ukraine with bird wintering areas in other regions show the potential for dissemination into new regions. Study showed large antigenic and genetic diversity of AIV in wild birds, moderate seroprevalence in mammals and potential presence IV in bats. Detection of sero- and PCR-positive mammals indicate spillover events, something that warrants additional studies.

Denys Muzyka (1,2,3), Oleksandr Rula (1), Muzyka Nataliia (1), Conny Tolf (2), Oleksandr Mezinov (1,3,4), Oleksandr Gaidash (3), Mary Pantin-Jackwood (5), Martin Beer (6), Jonas Waldenström (2) 1 National Scientific Center Institute of Experimental and Clinical Veterinary Medicine (IECVM), Kharkiv, Ukraine; 2 Linnaeus University, Kalmar, Sweden. 3 Department of Zoology, H.S. Skovoroda Kharkiv National Pedagogical University, Kharkiv, Ukraine; 4 The F.E. Falz-Fein Biosphere Reserve “Askania Nova” Askania-Nova Ukraine. 5Southeast Poultry Research Laboratory, Agricultural Research Service, USDA, Athens, Georgia, USA 6 Friedrich-Loeffler-Institut, Greifswald-Insel Riems Germany

Notable outbreaks, field and molecular epidemiology, and surveillance in wild birds