Matthew J. Neave

High pathogenicity avian influenza H5N1 clade 2.3.4.4b has caused a panzootic of devastating impact to poultry and wildlife globally. The Australian continent and broader Oceania until recently remained the last major region without confirmed detections. Here we report the first H5N1 clade 2.3.4.4b detections from two live seabirds - a brown skua and a southern giant petrel - found on the south coast of Western Australia in June 2026. Virus genome sequencing showed that both viruses were most closely related to H5N1 viruses detected recently on sub-Antarctic islands in the Southern Indian Ocean. In time-calibrated phylogeographic analyses, both viruses sampled in Western Australia clustered with viruses from Heard Island, a sub-Antarctic external territory of Australia. Ancestral location reconstruction also identified Heard Island as the most probable source location, although unsampled intermediate locations cannot be excluded. The two Western Australian detections were estimated to be independent incursions from Heard Island, rather than local transmission on mainland Australia. There was no evidence of reassortment with endemic avian influenza viruses in Australia, and both virus sequences retained key avian-like genetic markers and lacked known substitutions for reduced antiviral susceptibility. These detections revealed a Southern Ocean pathway of recurrent H5N1 incursions into Australia, highlighting the risk of potential establishment on the mainland and the need for heightened surveillance and rapid, nationally-coordinated, virus genomic characterisation.

Background: Adding to the global burden of high pathogenicity avian influenza (HPAI) H5N1, five HPAI H7 outbreaks occurred globally in 2024. Of these, three occurred in South‐East Australia, with the independent emergence of HPAI H7N9, H7N8 and H7N3, resulting in the destruction of 2 million poultry. Historical data demonstrate that H7 outbreaks in Australia do not occur randomly; rather, there is a strong association between the timing of the previous H7 outbreaks and rainfall patterns in South‐Eastern Australia. Methods: We aimed to address a hypothesis wherein prior to H7 outbreaks in poultry, there was a detectable change in H7 prevalence and/or virus diversity in wild bird populations. We addressed this using virological data from wild captured ducks, hunted ducks, as well as faecal environmental samples collected in South‐Eastern Australia from 2020 to 2024. We also interrogated changes in seroprevalence using both a commercial anti‐NP ELISA as well as haemagglutinin inhibition (HI) assays against H7. Results: Despite the collection of thousands of samples, there was only weak evidence to support our hypothesis, which provides strong incentive to evaluate current surveillance approaches for the purposes of risk prediction. However, in alignment with a previous analysis, there is strong support for a relationship between H7 outbreak probability and rainfall patterns across South‐East Australia. Conclusions: Overall, improved understanding of the ecology and evolution of H5 and H7 viruses in wild bird reservoirs is pivotal to global disease preparedness and response.

Background: The current panzootic of high pathogenicity avian influenza (HPAI) H5N1 has been catastrophic for wildlife, and following substantial geographic spread, clade 2.3.4.4b is found in every region aside from Oceania. Herein, we report the results of our third year of targeted surveillance of incoming migratory seabirds and shorebirds into Australia. Methods: From October to December 2024, we captured and sampled 946 migratory shorebirds (Charadriiformes) and seabirds (Procelariiformes) in Australia to rule out the arrival of HPAI H5N1. Results: We did not find evidence of HPAI H5N1 in any of the birds tested, and there were no reports of HPAI H5N1 in wildlife tested through other surveillance schemes in 2024. Unlike previous years, we detected a diversity of low pathogenicity avian influenza (LPAI) viruses in shorebirds. Through phylogenetic analysis, we revealed that the H3N7 and H4N7 viruses recovered from Red‐necked Stints were complex mosaic viruses, comprising segments of Eurasian, Australian shorebird and Australian waterfowl segments. One H1N7 virus detected comprised a wholly Eurasian introduction, confirming this incursion route for avian influenza viruses into Australian ecosystems. Conclusions: These results provide further evidence for the key role of long‐distance migratory shorebirds in introducing novel LPAI viruses into Oceania. While our focus on northern migration routes remained appropriate for HPAI H5N1 surveillance in 2024, the continued spread of HPAI H5N1 to sub‐Antarctic Islands demands consideration of a potential southern incursion route for Oceania in future.

High pathogenicity avian influenza (HPAI) has spread across the sub-Antarctic, causing significant wildlife impacts. We report its first detection in an Australian external territory, Heard Island and McDonald Islands, which supports over one million breeding seabirds and seals. Drone and ground surveys (October 2025, January 2026), combined with viral genome analysis, confirmed infection with Influenza A H5N1 clade 2.3.4.4b at Heard Island. Drone surveys revealed mass mortality in southern elephant seals, with 8,573 pups (62%) recorded dead across Heard Island by the final surveys. Mortality increased at an average rate of 5.6% per day in a subset of harems, and the highest observed mortality in a harem was 97%. Based on the average (76%) mortality in the final surveys, total estimated pup mortality at Heard Island was 13,359 (from a total population of 17,364 pups), though this may be an underestimate as mortality was ongoing at this time. HPAI was detected in six of nine species tested and, we suspect, led to elevated mortality in king and gentoo penguins. Phylogenetic analysis indicates the virus was introduced from Crozet Islands, with an estimated arrival around August 2025. These data show the continued easterly spread of HPAI around the sub-Antarctic, with severe but heterogeneous impacts across taxa. Our results demonstrate the value of drones for large-scale monitoring, underscoring the need for continued and enhanced HPAI surveillance across the Southern Ocean.

Northern Australia has long been a hotbed of arboviral discovery, and collections of viral isolates from Northern Australia represent an invaluable resource for both our knowledge of viral diversity and for disease preparedness and treatment. While discovery of novel viruses via classical virology methods is on the decline, next generation sequencing offers the possibility to speed up viral discovery, albeit at the expense of the collection of valuable life history data. By sequencing unknown isolates from historical viral collections, we may leverage both the rich data collected through classical virology and the power of identification using contemporary sequencing technologies. In the present study, we sequenced 76 historical viral isolates held at the Berrimah Veterinary Laboratory in Darwin, northern Australia, for which serological typing had yielded ambiguous results. We determined that 43 of these isolates belong to the genera Hapavirus, Orbivirus, and Orthobunyavirus. Several of these isolates are putatively novel genotypes or potential taxa, which has significant potential implications for human and animal health. This study demonstrates the utility of historical collections for viral discovery and characterisation and how considerable past efforts to isolate and characterise viruses can be enhanced using next generation sequencing approaches.

African swine fever virus (ASFV) is a highly stable DNA virus showing little genetic variation among genomes. This genetic stability has often posed challenges in tracking variants and identifying potential transmission chains as ASFV spreads into new regions. While mutations within individual sequenced genes are infrequent, the application of whole‐genome sequencing enables the identification of neutral and functional mutations across the entire genome, contributing to a deeper understanding of ASFV evolution and epidemiology. In this study, we sequenced whole genomes from 25 ASFV positive samples collected from Vietnam, Timor‐Leste and Papua New Guinea (PNG). We classified mutations across ASFV genes and non‐coding regions, while identifying mutations that may act as candidates for geographic‐based population genetic structuring. Overall, ASFV samples showed >99.8% genetic similarity to the Georgia 2007 isolate reference genome. Nonetheless, emergent genetic clusters rooted in geographic location were apparent. Multiple nonsynonymous mutations were found in sequenced genomes, often unique to ASFV collected within only one studied country. Of the observed mutations, four were found within genes of known function ( E199L , CP80R , B962L and B602L ), with the latter ( B602L ) being a novel mutation within a known targeted marker gene for conventional genotyping of the virus. This work highlights the benefits of incorporating whole‐genome sequencing into ongoing ASFV surveillance to better reflect the natural population genetic structuring within the species as it has spread across the Asia–Pacific region. Additionally, this work highlights the value of whole‐genome sequencing as a tool for actively monitoring emergent variants displaying functional divergence in key genes associated with ASFV proliferation and host selection.

The current panzootic of high pathogenicity avian influenza virus H5N1 demonstrates how viral incursions can have major ramifications for wildlife and domestic animals. Herein, we describe the recent incursion into Australia of two low pathogenicity avian influenza virus subtypes, H4 and H10, that exhibited contrasting evolutionary dynamics. Viruses detected from national surveillance and disease investigations between 2020-2022 revealed 27 genomes, 24 of which have at least one segment more closely related to Eurasian or North American avian influenza lineages than those already circulating in Australia. Phylogenetic analysis revealed that H4 viruses circulating in shorebirds represent a recent incursion from Asia that is distinct from those circulating concurrently in Australian waterfowl. Analysis of the internal segments further demonstrates exclusive, persistent circulation in shorebirds. This contrasts with H10, where a novel lineage has emerged in wild waterfowl, poultry and captive birds across Australia, and has likely replaced previously circulating H10 lineages through competitive exclusion. Elucidating different dynamics for avian influenza incursions supports effective disease risk identification and communication that better informs disease preparedness and response.

Herpesviruses are ubiquitous viruses which infect a wide range of hosts. Novel herpesviruses are being increasingly detected in free‐ranging bird populations and there are growing concerns for cross‐species infection and spillover events. Herein, multiple sporadic outbreaks of mortality caused by a herpesvirus are described in domestic geese in Queensland, Australia. Goose herpesvirus was initially detected in 1989 in south‐east Queensland, and this article details four further recent outbreaks and reports novel genome sequencing and phylogeny of the preliminarily designated anatid alphaherpesvirus 2 (AnHV‐2). Affected flocks were housed outdoors and comingled with other domesticated and wild anseriforms and other birds which were unaffected by disease. Affected geese displayed anorexia, lethargy, weakness, vomiting, and diarrhoea prior to death within 12–24 hr of the onset of clinical signs. Post‐mortem examinations showed variable hepatic necrosis, splenic necrosis, fibrinonecrotising enteritis, lymphoid necrosis, necrotising thymitis, necrotising adrenalitis, and vasculitis. Intranuclear inclusion bodies were observed in hepatocytes, biliary epithelium, small intestinal mucosal epithelium, thymus, endothelial cells, ovarian stromal cells, adrenal cortical cells, and neuronal cell bodies in peripheral nerve ganglia. Transmission electron microscopy visualised herpesviral particles in virus culture supernatant, and within the nuclei of hepatocytes, biliary epithelium, and endothelial cells in case tissues. The genome sequence of this herpesvirus, designated anatid alphaherpesvirus 2 (AnHV‐2), is described. While investigating goose mortalities, archived isolate from a swan with suspected herpesvirus infection was tested and genome sequencing identified a further novel herpesvirus, proposed anatid alphaherpesvirus 3 (AnHV‐3). The AnHV‐2 and AnHV‐3 genomes were more similar to each other, with a nucleotide identity of 76.1%, than to reference genome sequences. Phylogenetically, the new genomes formed a distinct clade within the alphaherpesvirus genus Mardivirus. We sequenced four AnHV‐2 genomes from different cases and these did not display consistent divergence over time or distance. Expanded surveillance and outbreak testing are recommended, facilitated by the development of a specific real‐time PCR for the rapid detection of AnHV‐2.