南澳大利亚近日发生三起大规模鸟类死亡事件，超过1000只凤头燕鸥疑似感染H5N1禽流感病毒身亡1。这些死亡事件发生在周三，地点分别为靠近袋鼠岛的Troubridge Island、North Page和South Page等偏远岛屿1。南澳大利亚总理彼得·马利诺斯基斯将此称为"重大升级"1。截至8月21日，该州已累计确诊177例H5禽流感病例1。
塔斯马尼亚也独立发现死亡事件，King Island上有28只小企鹅和3只凤头燕鸥死亡，正接受H5禽流感检测1。该州在上周四首次检测到H5禽流感，目前共有11例确诊病例，其中7例位于King Island1。
根据海外疫情经验，此次澳大利亚面临的H5N1病毒为clade 2.3.4.4b株系，该病毒自2020年出现以来已在欧洲、北美、南美和南极地区造成大规模野生动物死亡2。该病毒能同时侵袭鸟类的胃肠道、呼吸道和中枢神经系统，可感染500多个野生鸟类物种2。在西欧和北美地区，受灾最严重物种的成年鸟在繁殖期死亡率曾达25%-76%2。但国际经验也显示，首波疫情往往最为严重，随后死亡率会显著下降，幸存者逐步获得免疫力。例如欧洲三趾鸥在2023年的成鸟死亡率相比2022年下降了96%2。官方估计澳大利亚约20%的鸟类和10%的哺乳动物种群面临高到极端风险2。澳大利亚已开始跟随新西兰对人工饲养种群进行疫苗接种2。
South Australia has discovered three separate mass mortality events affecting more than 1,000 crested terns, suspected to have died from H5N1 avian influenza, marking what authorities describe as a significant escalation in the state's outbreak 1. The deaths occurred on Wednesday across remote islands including Troubridge Island, North Page, and South Page near Kangaroo Island 1. South Australian Premier Peter Malinauskas characterized the incidents as a "significant escalation," coming as the state recorded 177 confirmed H5 avian influenza cases by August 21 1.
Tasmania has simultaneously reported an independent mortality event on King Island, where 28 little penguins and 3 crested terns were found dead 1. The state first detected H5 avian influenza the previous Thursday and has since confirmed 11 cases overall, with 7 of these occurring on King Island 1. Both deceased bird populations are currently undergoing H5 avian influenza testing 1.
The H5N1 clade 2.3.4.4b virus strain circulating in Australia emerged in 2020 and has demonstrated the capacity to infect more than 500 wild bird species, including over 50 previously unrecorded species 2. According to international experience, initial outbreak waves tend to be the most severe, though death rates subsequently decline significantly as surviving populations develop immunity 2. In Western Europe and North America, breeding-age adult mortality rates among the hardest-hit species have reached 25 to 76 percent 2. Australia has implemented vaccination programs, carcass management, and surveillance measures in response, following New Zealand's approach for captive populations 2.
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