以兽类为例探讨我国陆生野生动物疫病监管中面临的问题与对策

近年来, 新型冠状病毒、SARS病毒和鼠疫等新发和再发性动物源疫病多是由兽类及其媒介携带的病原生物直接或间接感染而引发的, 不仅对人类健康和生态系统平衡造成了重大威胁, 而且威胁全球公共卫生安全、粮食安全和生物安全。结合我国重要陆生兽类疫源疫病发生的新情况和新特点, 本文重点总结了我国以陆生野生及非野生兽类(家畜为主)为重点的24种重要人兽共患病的监管情况, 并对这些疫源疫病的监管空缺进行了分析。由于病原生物的种类多及其感染传播方式多样, 我国人间和动物间疫情呈现多发态势, 新发和再发疫病防控面临严峻挑战。从目前情况来看, 我国重要野生动物疫源疫病呈现为多部门、多层监管的局面。全球化贸易剧增、非法猎杀、非法交易、违法违规养殖、滥食野生动物陋习、检疫环节失察等导致了当前我国野生动物疫源疫病的传染源头和传播链错综复杂, 加剧了人类与野生动物所携带的病原接触、感染和传播的风险。极端气候或灾害事件频发以及对新发再发传染病的认知不足导致难以从源头做好疫病防控。针对上述问题, 本文提出了从源头加强基础研究和全链条监管来积极防范陆生野生动物疫病疫情的对策和建议。     

新冠疫情下野生动物资源保护与利用的生物安全问题思考

自2019年底以来,全球范围内爆发了新型冠状病毒SARS-CoV-2引起的COVID-19大流行。SARS-CoV-2与蝙蝠来源的严重急性呼吸综合征(SARS)样冠状病毒高度同源,且穿山甲等野生动物中也鉴定出了同源性高的SARS样冠状病毒,提示SARS-CoV-2的源头与野生动物有关,野生动物资源利用与保护相关的生物安全问题凸显。在此背景下,本文介绍了常见的人畜共患病毒,提出了人类在利用野生生物资源时如何预防此类病毒的建议和思考。呼吁全社会应高度重视野生动物资源生物安全问题,形成"动物的健康即人类的健康、坚决不吃野味"的全民共识。     

同一健康理念下中国野生动物源疫病监测及响应体系发展对策

现代人类新发传染病中, 有60.3%是人兽共患病, 其中71.8%源于野生动物。野生动物是许多病原体的贮存库, 对人类和饲养动物会产生潜在的生物安全威胁。目前, 中国针对饲养动物疫病的监测检测系统和法律法规较为健全, 但针对野生动物的疫源疫病监测仍比较薄弱。根据“One Health”的理念, 野生动物疫源疫病的有效监测与相应防治措施的落实, 不仅可以为人兽共患病的大规模流行做出预警并降低其几率, 同时也为野生动物种群的健康提供了保障。本研究通过国际案例的比较分析, 提出有效的野生动物疫源疫病监测系统特征。同时, 通过对我国现有监测体系的研究分析, 结合利益相关方访谈以及实地调查, 提出了完善现有系统的主要措施建议。建议包括: (1)推进不同政府部门间的资源互通, 提高国家疫病监测体系应对跨学科、跨领域问题的综合能力; (2)针对人及饲养动物与野生动物接触频繁的生产生活方式, 应建立重点监测管理和响应机制; (3)提高对科学技术的重视, 包括建立野生动物疫病参考实验室、提升相关工作人员的技术能力等, 保障科学的监测方案和检测方法; (4)建立基于公众和现有监测资源的信息上报、汇总系统, 提升野生动物疫病监测的公众参与度和信息透明度。     

加强圈养野生动物疫病防控技术研究

2005年,我们进行了部分动物园饲养野生动物使用疫苗情况调查,了解到动物园动物使用36种疫苗预防31种疫病,其中涉及人兽共患病9种,7种疫病是动物园动物没有明确发生但在进行免疫预防的疾病。调查发现所用疫苗没有适应野生动物使用的疫苗和相应的免疫程序,疫苗接种均是参照家畜家禽的使用剂量和程序,大部分动物园动物没有进行禽流感、狂犬病等人兽共患病的监测,动物园之间的技术交流较少。主要原因是技术落后、设备缺乏、人员不济。应加强对圈养野生动物疾病防控技术的研究,加强对动物园动物重要疫病的监测,进一步加强动物园之间对疫病信息的交流和防疫资源的利用,加大对动物园动物疫病的研究投入。     

新冠肺炎时期公众对野生动物消费和贸易意愿的调查

新冠肺炎疫情的暴发, 使得对野生动物的消费与贸易中的公共健康安全问题引起广泛关注。为了给相关的立法和政策制定提供参考, 我们通过网络对于全国及部分海外华人发放问卷进行了调查, 共收回74,040份有效问卷。根据问卷调查结果, 本文对普通公众对于野生动物消费和贸易立法意愿及影响因素进行了分析。研究结果包括: (1)公众对全面取缔野味餐馆和集市、禁止消费野味、禁止野生动物及其制品的买卖以及禁止野生动物商业性活体展演的立法动议持赞成态度的比例均超过90%; (2)现有野生动物消费群体经历新冠肺炎疫情后倾向于停止消费行为; (3)曾经消费野生动物或周围有人从事野生动物相关产业的群体相比其他人群更有可能不支持全面禁止对野生动物的消费和贸易。结果表明, 全国人民代表大会常务委员会禁食野生动物的决定和修改野生动物保护法的动议在受高等教育者和城镇居民中有良好的公众基础。     

“野生动物”的概念框架和术语定义

“野生动物”(wild animal)一词不止在我国, 在全球的英语使用者中也有不同的含义。通过梳理相关研究、国内法和国际法背景下的定义和适用范围, 结合人类对动物繁殖和生活条件的控制情况, 本文提出了“野生动物”的二维概念框架, 梳理了动物从“野生”到“驯化”的12个连续状态。以下状态即未经中长期人工选择的动物类群应被视为野生动物: (1)其在荒野自然或人工环境(如城市或乡村)中自由生存繁殖, 无论是否存在人工投喂、经救护或辅助生殖后被放归的个体; (2)被捕捉圈养在人工环境中生活, 或源自野外但在圈养条件下出生的个体; (3)直系血亲(《濒危野生动植物种国际贸易公约》解释为世系前四代)仍有野外来源的人工繁育后代; (4)放生、逃逸或引入到自然环境中的人工繁育个体。在野生动物物种保护的目标和语境之下, 经过长期人工选择的驯化动物, 无论其是否在人类控制下生活, 如家养猫狗、家禽家畜或模式实验动物, 以及流浪猫狗、放生禽畜和野化家养动物等都不是“野生动物”。但对于一些经过一定程度的人工选择, 所处人类控制情况和对野外种群的影响各异(如经过多代人工繁育的驯养动物、因人类活动导致的外来动物等), 其是否需被作为野生动物管理, 则需要根据生态安全、物种管理、立法目标等特别设定监管范围。《中华人民共和国野生动物保护法》的保护对象可以考虑为: 受到人类威胁濒临灭绝的, 或者具有重要生态作用的野生动物物种, 其状态可不限于是在野外还是人工控制条件下。其他动物的管理, 可根据遗传资源保护、疫病防控、动物福利和生态安全等需要, 另外设立《动物福利法》《生物安全法》等, 并和已有的法律法规如《动物防疫法》《渔业法》等做好衔接。本文还就《野生动物保护法》可能采用的“野生动物”定义提出建议。     

野生动物狩猎、贸易和狩猎持续性研究进展

过度狩猎和过度贸易是当前生物多样性保护面临的重大挑战。虎骨和犀牛角贸易、东南亚一带的活野生动物非法狩猎和贸易、俄国远东地区及中俄边境野生动物产品非法贸易、热带地区的野生动物狩猎和丛林肉食贸易以及喜马拉雅区域的野生动物非法贸易正严重威胁着全球的野生动物资源。提倡狩猎持续性是解决过度贸易和过度捕杀的途径之一。 在众多的狩猎持续性模型中,“狩猎动物避难所模型”和“空间控制模型”提倡在狩猎区建保护区,有广泛的应用前景。了解偷猎动态和特征及其对濒危动物种群的影响,协调传统医药和野生动物保护间的关系,控制边境地区的野生动物非法狩猎和贸易,以及在保护实践中运用狩猎持续性模型是未来保护关注的焦点。野生动物非法狩猎和非法贸易严重威胁着我国的生物多样性保护和持续利用,但相关的研究却比较少。建议建立野生动物捕杀和贸易的监测机构,加强相关的立法、执法和保护区管理,开展野生动物捕杀和贸易研究。     

我国野生鸟类疫病传播风险及防范措施

众多疫病病毒来源于野生动物,具有向人类传播的风险,尤其是具有飞翔能力的鸟类不易控制,所携带的病毒传播广泛,威胁人畜安全。因此,充分了解鸟类携带疫病情况以及鸟类迁徙路线中重点区域的疫病风险,对疫病防控非常重要。本文总结了鸟类主要携带的病原类型,如冠状病毒、流感病毒、寄生虫和新城疫病毒等。着重探讨鸟类携带病原对生物安全防范重点区域的人员和动物的疫病风险,包括自然保护区、机场和禽类养殖场等,并从加强候鸟迁徙的动态监测、加强栖息地检疫和保护、家禽定期疫苗接种等方面提出疫病防范措施。     

云南省2014—2017年收容救护野生动物调查

通过对2014-2017年云南省被收容救护野生动物的物种数量、来源、频次等的调查和分析,结果发现:(1)云南省收容救护的野生动物超过93科269种,共计21 784只;其中,外来物种超过35种,以鸟类的种类和数量最多;(2)收容救护动物主要来源于执法单位移交,共20 485只,占94%;(3)非法动物贸易市场和渠道、人兽冲突、违规经营、民众缺乏对动物习性的了解是动物被收容救护的主要原因。管理部门需要加大监管力度,加强执法,严厉打击野生动物非法贸易,建立健全野生动物及制品市场准入机制,加强野生动物科普宣教工作,减少民众误抓误捉、随意放生外来物种等行为,进一步完善提高野生动物保护工作。     

切实加强自然保护区内野生动物的疫源疫病防控工作

野生动物是大自然的产物,是和我们一样在自然界生存的物种,也在维持自然生态系统的平衡中起到不可估量的作用。为了维持生物系统的稳态,为了使人与自然和谐发展,我们必须采取积极有效的措施去维护大自然的和谐,保护野生动物。在此,文本以我国某一自然保护区的实际工作情况为例,探讨了如何加强预防控制野生动物疫源疫病的具体措施,以期给相关部门的工作提供参考依据,为我国保护我国野生动物做出贡献。     

Viral infections at the animal–human interface—Learning lessons from the SARS-CoV-2 pandemic

This Lilliput explores the current epidemiological and virological arguments for a zoonotic origin of the COVID-19 pandemic. While the role of bats, pangolins and racoon dogs as viral reservoirs has not yet been proven, a spill-over of a coronavirus infection from animals into humans at the Huanan food market in Wuhan has a much greater plausibility than alternative hypotheses such as a laboratory virus escape, deliberate genetic engineering or introduction by cold chain food products. This Lilliput highlights the dynamic nature of the animal-human interface for viral cross-infections from humans into feral white tail deer or farmed minks (reverse zoonosis). Surveillance of viral infections at the animal-human interface is an urgent task since live animal markets are not the only risks for future viral spill-overs. Climate change will induce animal migration which leads to viral exchanges between animal species that have not met in the past. Environmental change and deforestation will also increase contact between animals and humans. Developing an early warning system for emerging viral infections becomes thus a societal necessity not only for human but also for animal and environmental health (One Health concept). Microbiologists have developed tools ranging from virome analysis in key suspects such as viral reservoirs (bats, wild game animals, bushmeat) and in humans exposed to wild animals, to wastewater analysis to detect known and unknown viruses circulating in the human population and sentinel studies in animal-exposed patients with fever. Criteria need to be developed to assess the virulence and transmissibility of zoonotic viruses. An early virus warning system is costly and will need political lobbying. The accelerating number of viral infections with pandemic potential over the last decades should provide the public pressure to extend pandemic preparedness for the inclusion of early viral alert systems.     

Exploring human-animal host interactions and emergence of COVID-19: Evolutionary and ecological dynamics

The novel coronavirus disease (COVID-19) that emerged in December 2019 had caused substantial morbidity and mortality at the global level within few months. It affected economies, stopped travel, and isolated individuals and populations around the world. Wildlife, especially bats, serve as reservoirs of coronaviruses from which the variant Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) emerged that causes COVID-19. In this review, we describe the current knowledge on COVID-19 and the significance of wildlife hosts in its emergence. Mammalian and avian coronaviruses have diverse host ranges with distinct lineages of coronaviruses. Recombination and reassortments occur more frequently in mixed-animal markets where diverse viral genotypes intermingle. Human coronaviruses have evolved through gene gains and losses primarily in interfaces where wildlife and humans come in frequent contact. There is a gap in our understanding of bats as reservoirs of coronaviruses and there is a misconception that bats periodically transmit coronaviruses to humans. Future research should investigate bat viral diversity and loads at interfaces between humans and bats. Furthermore, there is an urgent need to evaluate viral strains circulating in mixed animal markets, where the coronaviruses circulated before becoming adapted to humans. We propose and discuss a management intervention plan for COVID-19 and raise questions on the suitability of current containment plans. We anticipate that more virulent coronaviruses could emerge unless proper measures are taken to limit interactions between diverse wildlife and humans in wild animal markets.     

Evolutionary insights into the ecology of coronaviruses

Although many novel members of the Coronaviridae have recently been recognized in different species, the ecology of coronaviruses has not been established. Our study indicates that bats harbor a much wider diversity of coronaviruses than any other animal species. Dating of different coronavirus lineages suggests that bat coronaviruses are older than those recognized in other animals and that the human severe acute respiratory syndrome (SARS) coronavirus was directly derived from viruses from wild animals in wet markets of southern China. Furthermore, the most closely related bat and SARS coronaviruses diverged in 1986, an estimated divergence time of 17 years prior to the outbreak, suggesting that there may have been transmission via an unknown intermediate host. Analysis of lineage-specific selection pressure also indicated that only SARS coronaviruses in civets and humans were under significant positive selection, also demonstrating a recent interspecies transmission. Analysis of population dynamics revealed that coronavirus populations in bats have constant population growth, while viruses from all other hosts show epidemic-like increases in population. These results indicate that diverse coronaviruses are endemic in different bat species, with repeated introductions to other animals and occasional establishment in other species. Our findings suggest that bats are likely the natural hosts for all presently known coronavirus lineages and that all coronaviruses recognized in other species were derived from viruses residing in bats. Further surveillance of bat and other animal populations is needed to fully describe the ecology and evolution of this virus family.     

Differential stepwise evolution of SARS coronavirus functional proteins in different host species

Background  

SARS coronavirus (SARS-CoV) was identified as the etiological agent of SARS, and extensive investigations indicated that it originated from an animal source (probably bats) and was recently introduced into the human population via wildlife animals from wet markets in southern China. Previous studies revealed that the spike (S) protein of SARS had experienced adaptive evolution, but whether other functional proteins of SARS have undergone adaptive evolution is not known.     

Leptospirosis: Public health perspectives

Leptospirosis, caused by a spirochete of genus Leptospira, is considered the most widespread zoonosis in the world. It has a global distribution with a higher incidence in the tropics and subtropics, ranging from 10 to 100 human cases per 100,000 individuals. Leptospirosis is considered an “emerging” zoonosis due to increased contact between animals and humans and the resulting human encroachment into wildlife habitat. Climate change and its associated environmental shifts can affect the degree of transmission of leptospirosis. Surveillance for leptospirosis is important for early detection of cases because early treatment is crucial to decrease morbidity and mortality. In June 2012, the Council of State and Territorial Epidemiologists approved reinstatement of leptospirosis as a Nationally Notifiable Condition. Reinstatement of national surveillance will facilitate the assessment of the incidence, geographic distribution, trends, and risk factors associated with human cases and the identification of outbreaks and potential new animal reservoirs.     

The dynamics of trade in live wildlife across the Guangxi border between China and Vietnam during 1993–1996 and its control strategies

A survey on trade in live wild animals was conducted along the Guangxi border between China and Vietnam during 1993–1996. The results showed that there were 55 species, which were underestimated, involved in the trade, including 15 species of mammals, 10 species of birds, 29 species of reptiles and 1 species of amphibian. Many of them were species listed on Appendices I and II of CITES and on China's protection list (known as ASSP). During the investigation, about 2.29–29.325 tons of wildlife per day were imported to China form Vietnam. Some species with a large volume of trade may be over-exploited. Sixty-three percent of middle–high quality restaurants in three border cities and Nanning in Guangxi sold wildlife foods. Twenty kinds of wild animals were eaten at the restaurants. Although numbers of species involved in the trade remained fairly stable over the survey period, numbers of species listed in Appendices I and II of CITES and the state protection list had declined. The scale of wildlife markets in border cities of Guangxi and consumption levels of wildlife in the restaurants had been reduced because border control measures were enforced on the trade by local governments of China. However, the prices of the 5 main species in wildlife markets were still going up. This suggested that demand for wildlife in Guangxi was strong and will facilitate the illegal trade. The key steps to control the illegal wildlife trade between the two countries should focus on (i)suppression of illegal wildlife markets and prohibition of the sale of wildlife food in restaurants consisting of species listed in the ASSP inventory; (ii) international cooperation in the control of the trade; (iii) tighter enforcement of CITES for both countries; (iv) control of invasion of exotic species and epidemics of disease in the trade in China; and (v) education for wildlife conservation in China.