West Nile Fever

近日，西尼罗病毒在以色列、美国、西班牙等国家引发疫情，其中以色列情况相对严重。 以色列卫生部19日发布的声明，西尼罗河病毒今夏在以色列多地传播，过去3个月来共导致858人感染，其中至少62人死亡。 据报道，以色列每年6月至11月蚊虫滋生季节都会出现西尼罗病毒感染病例，但该病毒导致大规模人群感染尚属罕见。以政府提示卫生部门加快消灭蚊虫，对西尼罗病毒传播蔓延情况加强监控。 除以色列以外，美国、加拿大等国部分地区也出现西尼罗病毒疫情。加拿大安大略省渥太华公共卫生局21日发出预警，西尼罗病毒感染病例近期在渥太华“显著增加”。该卫生局说，研究人员近期同时对设在该市周边用于评估蚊虫种类和密度的多处检测站的采样样本进行西尼罗病毒检测，其中有5处的样本检测结果为阳性，这是继2017年以来第二高水平。2017年，渥太华周边同时有7处检测站的该样本检测结果为阳性。 安大略省安普赖尔、贝尔维尔等多地同样发现携带该病毒的蚊子，金斯顿地区上报一例疑似感染病例。    在美国纽约市，当地卫生部门19日通报，该市全部5个城区的蚊虫检测站均检测发现西尼罗病毒；7月底至今共出现4例感染病例，其中1人出现发烧症状，另外3人因出现神经性疾病住院治疗。此外，3名献血者的血液中也发现感染这一病毒的特征。 美国媒体21日发布的数据显示，得克萨斯州今年以来至少4人因感染西尼罗病毒死亡，该州北部地区近期出现逾40例西尼罗病毒感染病例。 另据西班牙媒体21日报道，西班牙韦尔瓦省、塞维利亚省本周共新增13例西尼罗病毒感染病例。塞维利亚省上周通报出现10例该病毒感染病例，其中一名87岁的感染者死亡。 西班牙加的斯省两处备受游客欢迎的旅游区也发现携带西尼罗病毒的蚊子，卫生部门预计西班牙的西尼罗病毒感染病例近期会进一步增多。 西尼罗病毒（West nile virus，WNV）是属于黄病毒科黄病毒属的RNA病毒，主要通过库蚊等蚊媒传播。 WNV最早于1937年在非洲乌干达西尼罗地区一位发热妇女血液标本分离到病毒并因此命名。在过去50多年中，许多国家均报告过西尼罗病毒引起的人类感染，其中1999年西尼罗病毒首次传入美国，5年后美国全境均有病例报告，引起全世界的高度关注。2004年，新疆喀什地区曾有西尼罗病毒脑炎的区域流行，2011年夏季，我国在该地区的尖音库蚊中首次分离到WNV。 流行病学 1、传染源 鸟是该病毒的贮存宿主，是西尼罗河病毒感染的主要传染源，目前已查明有70多种鸟与传播该病毒有关，其中有些鸟的死亡率很高，如乌鸦、大乌鸦、喜鹊、蓝鸟和灰鸟。 病人和隐性感染者是该病毒的传染源，但还未得到证实。 2、传播途径     西尼罗河病毒常通过蚊虫叮咬传播。人类，家禽与鸟类之间无法直接传播。病毒通常沿着鸟迁移的路径而传播到新的地方。 临床表现 80%左右的人在感染西尼罗病毒后不会发病，也没有任何症状。而另外20%左右的感染者在潜伏期1－6 天，部分长达20 天后。临床表现有发热型和脑炎型。两型均起病突然，体温骤升至40℃，部分患者伴有寒战。 1、发热型 突然发热，多表现为双波热，头痛、眼痛、全身肌肉酸痛，可伴咽炎及恶心、呕吐、腹痛、腹泻、食欲缺乏等胃肠症状。高热可致颜面潮红、结膜充血。腋下及腹股沟淋巴结肿大，无明显压痛。约有半数患者出疹，出疹时间在发热期或发热期末，颈背部、躯干及四肢出现淡红色玫瑰疹或斑丘疹，持续时间约为1 周，自行消退。轻型病例仅有类似感冒过程，全身反应轻，表现为自限性，80%患者经3－6 天自愈。 2、脑炎型 少数患者尤其是老年人及部分儿童、青少年感染后可引起脑炎、脑膜炎。此时病情较重，体温骤升、持续不降、剧烈头痛、恶心、呕吐、嗜睡，继而神志不清，颈项强直，出现异常神经反射，四肢发抖、痉挛、惊厥、昏迷、呼吸困难直至呼吸循环衰竭。 偶有皮肤水疱、急性脊髓前角灰质炎、心肌炎、胰腺炎、肝炎等发生。淋巴结消肿时间常需数月。西尼罗河热的病死率约为3%至5%。 诊断 血清学诊断是确定WNV感染的主要方式。标本通常使用ELISA (IgM捕获、阻塞和IgG)、HI和空斑减少中和试验(PRNT)来检测。 西尼罗河脑炎会使血清铁蛋白水平升高，可以与其他脑炎进行鉴别。    脑脊液检查淋巴细胞轻度增加，脑脊液蛋白含量增高，葡萄糖水平正常。 治疗 对于西尼罗河病毒感染的治疗，目前尚无特效药物。治疗主要以支持性疗法为主，包括对症治疗、控制并发症以及加强患者的免疫支持。此外，目前尚无人类可用疫苗，预防西尼罗河病毒感染的主要手段为切断传播途径，即有效的、大规模灭蚊，户外活动时应采取措施以防蚊子叮咬等。 是否对我国造成影响？ 南方医科大学公共卫生学院生物安全研究中心主任赵卫表示，西尼罗河病毒主要通过库蚊传播，而我国库蚊分布范围广，因此存在一定的输入风险。 他提醒，“普通居民尽量不要去疫区旅游，必须到疫区的人需要采取措施以防蚊子叮咬，如涂抹驱避剂、穿长袖衣服等。”   来源｜央视新闻 撰文 | Anna.An 编辑 | Swagpp ● 太痛心！江苏、浙江大三甲连续痛失两位国宝级科主任！均不满60岁！网友痛悼：救了很多人，唯独救不了自己，终于明白“医者不寿”的心酸 ● 猪肉牛肉要少吃！Nature子刊：超20万人36年随访发现，红肉吃得多，糖尿病风险更高！罪魁祸首是它 ● 重磅！华西刘进：写病历、拉钩不是干杂活，对规培生很重要！医生要有疲劳下工作的能力！50% 的规培生月收入超过 5000 元了？ 版权说明：梅斯医学（MedSci）是国内领先的医学科研与学术服务平台，致力于医疗质量的改进，为临床实践提供智慧、精准的决策支持，让医生与患者受益。欢迎个人转发至朋友圈，谢绝媒体或机构未经授权以任何形式转载至其他平台。 点击下方「阅读原文」 立刻下载梅斯医学APP！

Researchers demonstrate the contribution of climate change to the spatial expansion of West Nile virus in Europe, a virus that constitutes a new public health threat in the continent. Their findings highlight a notable increase in the area ecologically suitable for the virus circulation since the beginning of last century and an increase in the human population at risk of exposure, due in part to climate change. In a study published this week in the journal Nature Communications, researchers from the Spatial Epidemiology Lab (SpELL, ) of the University of Brussels (ULB) and their collaborators demonstrate the contribution of climate change to the spatial expansion of West Nile virus in Europe, a virus that constitutes a new public health threat in the continent. Their findings highlight a notable increase in the area ecologically suitable for the virus circulation since the beginning of last century and an increase in the human population at risk of exposure, due in part to climate change. West Nile virus is an emerging pathogen in Europe and represents a public health threat in previously non-affected European countries. Occurring in a cycle involving transmission between bird and mosquito species, this virus can be transmitted to humans by mosquitoes and induce West Nile fever. While most human infections are asymptomatic, around 25% of victims develop symptoms such as fever and headache, and less than 1% develop more severe neurological complications that can lead to death. While climate change has been cited as a potential driver of the emergence of West Nile virus on the European continent, a formal evaluation of this causal relationship was lacking. In a study published in the journal Nature Communications, researchers from the University of Brussels (ULB) -- Diana Erazo and Simon Dellicour from the Spatial Epidemiology Laboratory -- and their collaborators investigated the extent to which West Nile virus spatial expansion in Europe can be attributed to climate change while accounting for other direct human influences such as land use and human population changes. To this end, they adopted a machine learning approach to predict the risk of local West Nile virus circulation given local environmental conditions. They subsequently unravelled the isolated effect of climate change by comparing factual simulations to a counterfactual where climate change had been removed. "Our results point towards a significant responsibility of climate change in the establishment of West Nile virus in the south-eastern part of the continent. In particular, we identify that current West Nile virus hotspots in Europe are most likely to be attributed to climate change" explains Diana Erazo, first author of the study and post-doctoral researcher at the Spatial Epidemiology Lab. "Our results also demonstrate a recent and drastic increase of the population at risk of exposure. While this increase is partly due to an increase in population density, we show that climate change has also been a critical factor driving the risk of West Nile virus exposure in Europe." Made possible by the collaboration of researchers with different expertise, the study is also the result of an interdisciplinary approach. "Our work illustrates how climate data could be effectively used in an epidemiological context by estimating the past and present-day ecological suitability of the virus, filling another analytical gap between climate science and epidemiology" says Simon Dellicour, supervisor of the study and head of the Spatial Epidemiology Lab. "With climate change emerging as a critical public health challenge, future work should explore the evolution of infectious disease distributions under different scenarios of future climate change to inform surveillance and intervention strategies."

Scientists have developed vaccine will protect farmed saltwater crocodiles from West Nile virus (WNV), providing economic and biodiversity benefits to northern Australia. A University of Queensland developed vaccine will protect farmed saltwater crocodiles from West Nile virus (WNV), providing economic and biodiversity benefits to northern Australia. Dr Jody Hobson-Peters from UQ's School of Chemistry and Molecular Biosciences said the virus, which is prevalent in high rainfall years, threatens the commercial viability of the $100million a year crocodile hide farming industry. "Crocs infected with the local strain of WNV, known as Kunjin virus, develop small skin lesions called pix, which renders their hide unsaleable," Dr Hobson-Peters said. "WNV infection can affect up to 30 per cent of croc hides, costing the industry as much as $10million in a single year. "If we were to experience consecutive years of high rainfall, the virus could render the crocodile farming industry unviable and threaten the current conservation model. "It would also disrupt an industry that contributes to Indigenous livelihoods and economic development opportunities in the Northern Territory and Far North Queensland." UQ's Professor Roy Hall said the vaccine is based on a benign 'Binjari' virus isolated from Australian mosquitoes and is the first of its kind to achieve proven safety and efficacy in crocodiles. "We have demonstrated that our vaccine induces a robust, immune response in vaccinated animals after two doses," Professor Hall said. "Crocodiles that received the vaccine developed strong protective immunity against WNV, without the virus replicating." UQ has received funding from the Australian Research Council to work with the Centre for Crocodile Research to assess the vaccine's long-term performance. Director of the Darwin-based Centre for Crocodile Research, Dr Sally Isberg said the surge in the wild crocodile population in recent decades was made possible by the farmed crocodile industry. "It's not just an economic threat we're facing -- croc farming has played a pivotal role in returning this apex predator from the brink of extinction over the past 60 years," Dr Isberg said. "The captive-breeding industry promotes sustainable practices and places an economic value on crocodiles, meaning communities living with or near crocs are more tolerant of their presence in waterways and are incentivised to protect their habitats. "As a result, other species that co-inhabit with crocs are protected, such as the brolga, jabiru and long-necked turtle." The research is published in npj Vaccines, and is an outcome of UQ's Dr Gervais Habarugira's PhD thesis. The team is working with the Australian veterinary vaccine company Treidlia BioVet, to develop a commercial version of the vaccine for wider industry use. UQ acknowledges the contributions of the Australian crocodile industry and biotechnology company Vaxine Pty Ltd.