Abstract Introduction Repeated incursions of highly pathogenic avian influenza virus (HPAIV) H5 subtype of Gs/GD lineage pose a serious threat to poultry worldwide. We provide a detailed analysis of the spatio-temporal spread and genetic characteristics of HPAIV Gs/GD H5N8 from the 2019/20 epidemic in Poland. Material and methods Samples from poultry and free-living birds were tested by real-time RT-PCR. Whole genome sequences from 24 (out of 35) outbreaks were generated and genetic relatedness was established. The clinical status of birds and possible pathways of spread were analysed based on the information provided by veterinary inspections combined with the results of phylogenetic studies. Results Between 31 December 2019 and 31 March 2020, 35 outbreaks in commercial and backyard poultry holdings and 1 case in a wild bird were confirmed in nine provinces of Poland. Most of the outbreaks were detected in meat turkeys and ducks. All characterised viruses were closely related and belonged to a previously unrecognised genotype of HPAIV H5N8 clade 2.3.4.4b. Wild birds and human activity were identified as the major modes of HPAIV spread. Conclusion The unprecedentedly late introduction of the HPAI virus urges for re-evaluation of current risk assessments. Continuous vigilance, strengthening biosecurity and intensifying surveillance in wild birds are needed to better manage the risk of HPAI occurrence in the future.

中文翻译：

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2019-2020年波兰高致病性H5N8禽流感


摘要 引言 Gs/GD 谱系高致病性禽流感病毒 (HPAIV) H5 亚型的反复入侵对全球家禽构成严重威胁。我们对波兰 2019/20 年度流行的 HPAIV Gs/GD H5N8 的时空传播和遗传特征进行了详细分析。材料和方法 通过实时 RT-PCR 测试来自家禽和自由生活鸟类的样品。生成了 24 起（共 35 起）疫情的全基因组序列，并建立了遗传相关性。根据兽医检查提供的信息结合系统发育研究的结果，分析了鸟类的临床状况和可能的传播途径。结果 2019年12月31日至2020年3月31日期间，波兰9个省份确认商业和散养家禽养殖场爆发35起疫情，其中1起野鸟病例。大多数疫情是在肉火鸡和鸭肉中发现的。所有特征病毒都密切相关，属于以前未被识别的 HPAIV H5N8 进化枝 2.3.4.4b 基因型。野生鸟类和人类活动被确定为 HPAIV 传播的主要方式。结论 HPAI 病毒的引入前所未有地晚，迫切需要重新评估当前的风险评估。需要持续保持警惕，加强生物安全并加强对野生鸟类的监测，以更好地管理未来高致病性禽流感发生的风险。