ABSTRACT

Highly pathogenic avian influenza viruses (HPAIV), such as H5N1, H5N6, and H7N9, have been reported to frequently infect humans, but acute encephalitis caused by HPAIV in humans has been rarely reported. We report the first critical case of acute encephalitis with mild pneumonia caused by the H5N6 virus. On January 25 of 2022, a 6-year-old girl with severe neurological symptoms was admitted to our hospital and rapidly developed into seizures and coma. Brain imaging showed abnormalities. Electroencephalogram (EEG) presented abnormal slow waves. Cerebrospinal fluid (CSF) contained elevated protein (1.64 g/L) and white cells (546 × 10⁶/L). Laboratory investigations revealed abnormally elevated transaminases, lactate dehydrogenase, and cytokines in serum. A novel reassortant H5N6 virus was identified from the patient’s serum, CSF, and tracheal aspirate specimens. Phylogenic analysis indicated that this virus was a novel reassortant avian-origin influenza A (H5N6) virus that belonged to clade 2.3.4.4b. This patient was diagnosed with acute encephalitis and discharged from the hospital accompanied by a language barrier. An epidemiological investigation confirmed that wild waterfowls were the direct source of infection in this case. Our study highlights the urgent need to pay attention to acute encephalitis caused by HPAIV.

摘要

据报道，H5N1、H5N6和H7N9等高致病性禽流感病毒（HPAIV）经常感染人类，但由HPAIV引起的人类急性脑炎却鲜有报道。我们报告了首例由 H5N6 病毒引起的伴有轻度肺炎的急性脑炎重症病例。2022年1月25日，一名6岁女孩，出现严重的神经系统症状，被我院收治，并迅速发展为癫痫发作和昏迷。脑成像显示异常。脑电图（EEG）呈现异常慢波。脑脊液 (CSF) 含有升高的蛋白质 (1.64 g/L) 和白细胞 (546 × 10 ⁶/L)。实验室检查显示血清中转氨酶、乳酸脱氢酶和细胞因子异常升高。从患者的血清、脑脊液和气管吸出物样本中鉴定出一种新型重配 H5N6 病毒。系统发育分析表明该病毒是属于进化枝2.3.4.4b的新型重配禽源甲型流感（H5N6）病毒。该患者被诊断为急性脑炎，并伴有语言障碍出院。流行病学调查证实，野生水禽是该病例的直接感染源。我们的研究强调迫切需要关注由 HPAIV 引起的急性脑炎。