武汉市新洲区2021年高致病性禽流感和新城疫免疫抗体监测数据浅析

高致病性禽流感（highly pathogenic avian influenza, HPAI）和新城疫（newcastle disease, ND）等烈性传染病对养禽业危害严重,是养禽业需重点防控的疾病,其中HPAI是国家规定的强制免疫疫病。武汉市新洲区为家禽养殖大区,有规模禽场350余家,养殖规模近1140万只。为了解2021年度武汉市新洲区规模养殖场高致病性禽流感和新城疫免疫抗体合格率,武汉市新洲区农业技术推广服务中心连续12个月对辖区内规模鸡场进行蛋样抽检,运用血凝和血凝抑制试验,分别检测了高致病性禽流感H5亚型、H7亚型和新城疫的免疫抗体。结果显示,高致病性禽流感H5亚型、H7亚型和新城疫的整体免疫抗体合格率分别为94.1%、96.4%和88.9%,均达到了农业农村部规定的免疫抗体合格率不低于70.0%的标准。     

The Perceived Value of Passive Animal Health Surveillance: The Case of Highly Pathogenic Avian Influenza in Vietnam

Economic evaluations are critical for the assessment of the efficiency and sustainability of animal health surveillance systems and the improvement of their efficiency. Methods identifying and quantifying costs and benefits incurred by public and private actors of passive surveillance systems (i.e. actors of veterinary authorities and private actors who may report clinical signs) are needed. This study presents the evaluation of perceived costs and benefits of highly pathogenic avian influenza (HPAI) passive surveillance in Vietnam. Surveys based on participatory epidemiology methods were conducted in three provinces in Vietnam to collect data on costs and benefits resulting from the reporting of HPAI suspicions to veterinary authorities. A quantitative tool based on stated preference methods and participatory techniques was developed and applied to assess the non‐monetary costs and benefits. The study showed that poultry farmers are facing several options regarding the management of HPAI suspicions, besides reporting the following: treatment, sale or destruction of animals. The option of reporting was associated with uncertain outcome and transaction costs. Besides, actors anticipated the release of health information to cause a drop of markets prices. This cost was relevant at all levels, including farmers, veterinary authorities and private actors of the upstream sector (feed, chicks and medicine supply). One benefit associated with passive surveillance was the intervention of public services to clean farms and the environment to limit the disease spread. Private actors of the poultry sector valued information on HPAI suspicions (perceived as a non‐monetary benefit) which was mainly obtained from other private actors and media.     

Animal Health Policy Principles for Highly Pathogenic Avian Influenza: Shared Experience from China and Canada

Animal health policy for highly pathogenic avian influenza (HPAI) must, for the time being, be based on expert opinion and shared international experience. We used the intellectual capital and knowledge of experienced Chinese and Canadian practitioners and policy makers to inform policy options for China and find shared policy elements applicable to both countries. No peer‐reviewed comprehensive evaluations or systematic regulatory impact assessments of animal health policies were found. Sixteen guiding policy principles emerged from our thematic analysis of Chinese and Canadian policies. We provide a list of shared policy goals, targets and elements for HPAI preparedness, response and recovery. Policy elements clustered in a manner consistent with core public health competencies. Complex situations like HPAI require complex and adaptive policies, yet policies that cross jurisdictions and are fully integrated across agencies are rare. We encourage countries to develop or deploy capacity to undertake and publish regulatory impact assessments and policy evaluation to identify policy needs and provide a basis for evidence‐based policy development.     

H5亚型高致病性禽流感二价灭活疫苗对不同日龄家禽的免疫原性研究

为找出禽流感母源抗体及免疫抗体消长规律,对不同日龄的蛋鸡进行了免疫,并进行了跟踪检测,为制定禽的免疫程序提供科学依据。从试验结果可见,雏鸡母源抗体水平与种鸡的抗体水平相关,种鸡血清中H5亚型禽流感HI抗体水平与子代母源抗体消长规律呈正比。     

2013－2019年广西边境地区低致病性禽流感病毒监测分析

为了解广西边境地区低致病性禽流感病毒（low pathogenic Avian influenza virus,LPAIV）的流行情况,本研究对2013-2019年在广西边境地区的规模养殖场和活禽市场采集的33 964份家禽棉拭子样品,采用鸡胚接种方法进行病毒分离,并结合血凝抑制试验和RT-PCR等方法鉴定禽流感病毒的亚型。结果显示,共有3 892份样品分离到LPAIV,2013-2019年的样品病毒分离率分别为17.39%、11.23%、13.59%、9.31%、9.09%、9.12%和15.21%,总分离率为11.46%,其中2013年样品的病毒分离率最高。分离到的LPAIV包括H1、H3、H4、H6、H9、H10和H11 7种亚型,样品病毒分离率分别为0.14%、4.37%、0.19%、4.06%、2.69%、0.01%和0.003%。其中活禽市场分离到H1、H3、H4、H6、H9、H10和H11 7种亚型流感病毒,样品病毒分离率分别为0.19%、5.53%、0.21%、5.29%、3.41%、0.01%和0.004%,总分离率为14.64%;而养殖场分离到H3、H4、H6和H9 4种亚型流感病毒,样品病毒分离率分别为1.26%、0.12%、0.79%和0.78%,总分离率为2.95%,养殖场的分离率远低于活禽市场（14.64%）。鸡源样品的病毒分离率为5.77%,水禽样品的病毒分离率为15.10%,环境样品的病毒分离率为21.67%,水禽和环境样品的病毒分离率远高于鸡。结果表明,当前广西边境地区家禽携带多种亚型LPAIV,水禽是高风险禽群,应进一步加强监测和防控;活禽市场污染严重,应进一步加强对活禽市场的监管力度,建立和实施更加科学有效的活禽市场运营机制。     

我国H5和H7N9亚型高致病性禽流感的监测及疫情暴发分析

禽流感病毒（avian influenza virus,AIV）是一种重要的人兽共患病病原,严重制约养禽业的健康发展,并对公共卫生安全构成极大威胁。其中,H5（H5N1、H5N2、H5N6、H5N8等）和H7N9亚型高致病性禽流感病毒（highly pathogenic avian influenza virus,HPAIV）引起的高致病性禽流感（highly pathogenic avian influenza,HPAI）对我国养禽业危害巨大。通过实施强制免疫,疫情得到了控制,但在禽群中仍散状暴发,并出现多种新型病毒,防控形势依然严峻。本文总结了截至2021年9月我国禽类暴发H5和H7N9亚型HPAI的所有官方公布的疫情暴发事件以及监测数据,分析了其流行特点,以期为禽流感的预警和防控提供参考。     

天津市某鸡场高致病性H7N9流感紧急流行病学调查

2017年5月13日,天津市某蛋鸡场出现疑似流感疫情,发病鸡伴有呼吸困难、咳嗽等症状,死亡率持续升高,经国家参考实验室确诊为高致病性H7N9流感疫情。为查找可能风险因素并提出防控建议,进行了紧急流行病学调查。结果显示,本次疫情袭击率为10.8%,车流、人流以及野鸟带毒入场可能是引起疫情的主要原因。本次疫情得到有效处置,未发生扩散。     

禽流感病毒的分子致病机理及其跨种传播的分子机制研究进展

禽流感病毒是引起家禽及野生鸟类禽流感的病原,能够跨种间传播给人类及虎等哺乳动物,给养禽业造成巨大的经济损失,也严重威胁人类健康。文中综述了近些年来禽流感病毒分子致病机理及其跨种间传播分子机制的国内外研究成果,以期为禽流感的科学防控提供参考。     

武定鸡IFN-γ基因-316A/GSNP对H5N1亚型高致病性禽流感灭活疫苗免疫效果的影响

为探讨γ干扰素(IFN-γ)基因-316A/G SNP对云南地方鸡品种武定鸡接种H5N1亚型高致病性禽流感(HPAI)灭活疫苗效果的影响,随机选取100只同日龄母源抗体阴性的武定鸡,应用PCR结合DNA测序确定其IFN-γ基因-316A/G SNP分布状况,同时应用血凝抑制试验(HI)测定免疫前和再次免疫后血浆特异抗体水平,随后采用卡方检验总样本基因型频率是否处于Hardy-Weinberg平衡,并采用最小二乘分析检查基因型组间抗体水平差异。结果发现,该试验样本符合Hardy-Weinberg平衡(P0.05),并且存在随着A取代G抗体水平呈逐渐升高的趋势,即与GG基因型(n=20,7.90±0.343)相比,AG基因型(n=56,8.62±0.205)的抗体水平升高不显著(P0.05),但AA基因型(n=24,9.04±0.313)的抗体水平升高显著(P=0.01570.05)。结果表明,IFN-γ基因-316A/G SNP与武定鸡HPAI特异性抗体应答水平存在关联性,这对培育AA基因型抗病品系和制定合理的HPAI免疫程序具有积极的指导意义。     

安徽省合肥市家禽高致病性禽流感血清学调查

2017年秋,我国开始采用高致病性禽流感(H5+H7)二价灭活疫苗,对家禽实行强制免疫。为评价该疫苗在合肥市家禽中的免疫效果,科学制定该地区免疫计划和防控措施,2017年10月—2018年10月,在春季和秋季集中强制免疫后,分别随机抽取养殖场、交易市场和自然村散养户家禽血清样品,进行3次集中抗体监测;在2018年春季集中免疫前和免疫后,选取22个固定家禽养殖场,开展定点抗体监测。集中监测结果显示:高致病性禽流感抗体场点合格率从2017年秋季的48.0%,分别提高到2018年春季的96.6%和秋季的95.5%,2018年的H5、H7亚型个体合格率均高于2017年秋季水平,差异均有统计学意义(P<0.01)。定点监测结果显示:免疫后21d,H5亚型禽流感抗体个体合格率由92.6%降到58.2%,但60d后又大幅回升到90.8%,差异极显著(P<0.01);而H7亚型抗体合格率却直线上升,个体合格率差异有统计学意义(P<0.01)。上述结果表明,高致病性禽流感(H5+H7)二价灭活疫苗防护效果较好,可显著提升H5和H7亚型抗体场点合格率和个体合格率,使其达到免疫保护水平,因此应继续加强该疫苗的免疫、监测,根据实际情况及时补免。     

实验性鸡大肠杆菌病病理学动态变化

用致病性大肠杆菌O18分离株和／或低致病性禽流感病毒（Mildly pathogenic avian influenza virus ,MPAIV)接种10－12日龄SPF鸡。在接种后1－96h进行临床症状与大体病理变化、组织学观察发现：大肠杆菌接种组、MPAIV接种组和健康接种组除扑杀鸡外未见鸡死亡，MPAIV与大肠杆菌混合接种组除扑杀鸡外死亡率为24％。混合接种组的病变比大肠杆菌接种组出现的时间早，恢复也慢，各脏器的病理变化更严重。MPAIV主要引起各实质器官的坏死，结果表明，大肠杆菌经气管内接种后试验鸡主要表现为呼吸道的炎症反应；MPAVI可使鸡大肠杆菌病严重化。     

实验性鸡大肠杆菌病的超微动态病理变化

10～ 12日龄 SPF鸡 180只 ,随机分为 4组 ,分别气管内注射致病性大肠杆菌 O18分离株 (大肠杆菌接种组 )、低致病性禽流感病毒 (mildly pathogenic avian influenza virus,MPAIV) H9N2株 (MPAIV接种组 )、先接种 MPAIV再接种大肠杆菌 (混合接种组 ) ,并设健康对照组 ,分别于接种后不同时间 ,取气管、肺、气囊、胸腺、法氏囊、脾、肝和肾组织 ,制作超薄切片 ,电镜观察。结果表明 ,MPAIV与大肠杆菌混合接种组比大肠杆菌接种组出现病变的时间早、恢复慢 ;在大肠杆菌接种组 ,接种后 3h气囊上皮和间质细胞中都可见典型的大肠杆菌 ;在混合接种组 ,接种后 3h,气囊间质细胞的吞噬泡中可见多个 MPAIV粒子。由此认为 ,MPAIV可使鸡大肠杆菌病严重化 ,大肠杆菌对 MPAIV的入侵和在鸡体内的复制可能有促进作用。     

野鸟在禽流感流行病学中的作用研究进展

作者对中国特别是辽宁省野鸟存在和迁移情况进行了详细总结;同时结合野鸟的迁移,携带禽流感病毒情况,深入分析、探讨野鸟在禽流感传播中的作用,明确预防控制野鸟禽流感的重要性,为野鸟禽流感的防控提供参考。     

Risk factors and characteristics of H5N1 Highly Pathogenic Avian Influenza (HPAI) post-vaccination outbreaks

Highly pathogenic avian influenza (HPAI) virus H5N1 is now endemic in South-East Asia but HPAI control methods differ between countries. A widespread HPAI vaccination campaign that started at the end of 2005 in Viet Nam resulted in the cessation of poultry and human cases, but in 2006/2007 severe HPAI outbreaks re-emerged. In this study we investigated the pattern of this first post-vaccination epidemic in southern Viet Nam identifying a spatio-temporal cluster of outbreak occurrence and estimating spatially smoothed incidence rates of HPAI. Spatial risk factors associated with HPAI occurrence were identified. Medium-level poultry density resulted in an increased outbreak risk (Odds ratio (OR) = 5.4, 95% confidence interval (CI): 1.6–18.9) but also climate-vegetation factors played an important role: medium-level normalised difference vegetation indices during the rainy season from May to October were associated with higher risk of HPAI outbreaks (OR = 3.7, 95% CI: 1.7–8.1), probably because temporal flooding might have provided suitable conditions for the re-emergence of HPAI by expanding the virus distribution in the environment and by enlarging areas of possible contacts between domestic waterfowl and wild birds. On the other hand, several agricultural production factors, such as sweet potatoes yield, increased buffalo density, as well as increased electricity supply were associated with decreased risk of HPAI outbreaks. This illustrates that preventive control measures for HPAI should include a promotion of low-risk agricultural management practices as well as improvement of the infrastructure in village households. Improved HPAI vaccination efforts and coverage should focus on medium poultry density areas and on the pre-monsoon time period.     

MPAIV、NDV Lasota株分别与较低致病性禽源E.coli的联合感染试验

以 2× 1 0 5EID50 的低致病性禽流感病毒 ( mildly pathogenic avian influenza virus,MPAIV)、2× 1 0 6 EID50 新城疫病毒 L asota株( Newcastle disease virus Lasota strain,NDVL asota)气管内注射 1 0日龄 SPF鸡 ,2 4h后 ,同剂量、同法重复感染一次 ;48h后 ,分别气管内注射较低致病性禽病原性大肠杆菌 1 2 0( O1 8)和 1 73( O2 6 )株 ,2× 1 0 7CFU/羽 ,2 4h后同剂量、同法重复攻毒一次 ,连续观察 1 0d。结果 :MPAIV单独感染组死亡率为 53% ;NDV Lasota株单独攻毒组未见死亡 ;大肠杆菌 1 2 0株单独攻毒组死亡率为 40 % ,1 73株单独攻毒组死亡率为 7% ;MPAIV与大肠杆菌1 2 0株联合攻毒组的死亡率为 87% ,NDV L a-sota株与 1 2 0株联合攻毒组的死亡率为 40 % ;MPAIV与大肠杆菌 1 73株联合攻毒组的死亡率为 80 % ,NDV Lasota株与 1 73株联合攻毒组的死亡率为 2 0 %。     

H5N1亚型高致病性禽流感病毒对鸽的致病性分析

为评估H5N1亚型禽流感病毒对鸽的致病性,用我国2004年分离的一株H5NI亚型禽流感病毒A/pigeon/GD/C2/2004( H5NI)人工感染4周龄鸽,进行了致病性试验.结果表明,该株病毒以106EID50/I00μL剂量感染能致死鸽,致死率为22.2％,病毒能在感染鸽体内广泛分布,其中肺脏和肾脏中病毒含量达到...     

内蒙古地区猪群中HP-PRRS的流行病学调查

为掌握内蒙古地区猪群中高致病性猪蓝耳病(HP-PRRS)的流行规律,应用流行病学调查、病理剖检、血清学试验、分子生物学等方法对发病猪群进行了HP-PRRSV的研究.结果表明,临床上发病猪多为合并感染,病死率高.PCR检测16份送检样品中, HP-PRRS阳性率62.5%,猪蓝耳病(PRRS)阳性率18.8%,猪瘟(CSF)阳性率25%,伪狂犬病(PR)阳性率12.5%,猪细小病毒(PP)感染阳性率0%,猪圆环病毒2型(PCV-2)感染阳性率37.5%,而且以上这些猪病病毒抗体在猪群中普遍高于未发生HP-PRRS疫情之前.由此可见,目前猪病疫情是以HP-PRRSV为优势毒株,结合其他病原体混合感染而引发的.     

对厦门市某猪场一起仔猪副猪嗜血杆菌病的暴发调查

[目的]2013年11月底至12月上旬,厦门市某猪场的一间产房兼保育猪舍出现了大规模的仔猪发病和死亡情况,为了找出引起病症暴发的可能病因,[方法]采用描述性流行病学方法对疫情特点进行描述,对发病风险因素进行分析。[结果]断奶仔猪袭击率为85.7%,病死率为66.5%;哺乳仔猪袭击率为60.3%,病死率为54.9%,断奶仔猪的发病风险是哺乳仔猪的1.4倍（95%CI：1.3~1.6）;从饲养密度看,高床上每栏饲养15只以上的断奶仔猪的发病风险是每栏饲养15只及以下的断奶仔猪的1.6倍（95%CI：1.4~1.8）;从母猪每窝产子数看,产床上母猪1胎产子8只以上的哺乳仔猪的发病风险是1胎8只及以下的哺乳仔猪的1.2倍（95%CI：1.04~1.4）。[结论]结合剖检变化和实验室检测结果,判定这可能是一起仔猪应激反应引发感染副猪嗜血杆菌病的暴发事件。最后根据调查分析结果,建议场主加强生产管理,提高猪群抗病能力。     

山西省某灰雁养殖场H5N6高致病性禽流感暴发调查

2017年5月26日至6月5日,山西省某养殖专业合作社养殖的灰雁出现了发热、腹泻(拉黑绿稀便)、头颈后仰、失明等症状,并陆续死亡,共死亡625只,袭击率为52.08%(625/1 200),经国家禽流感参考实验室检测,确诊为H5N6亚型高致病性禽流感。采用问卷调查方式,对场内基本情况、免疫情况、调运情况及发病情况进行调查。调查发现,发病灰雁系5月26日调入,调运前未进行H5N6亚型禽流感免疫,因此调入时可能已感染禽流感病毒是此次暴发的主要原因。对全市范围的养殖禽类进行禽流感疫情排查,未发现其他疫情。调查结果提示:加强所有饲养禽类的禽流感免疫,建立有效的免疫屏障,对于控制禽流感疫情暴发具有重要意义;养殖场在购入禽类时,应认真查验检疫票证,了解免疫背景,并建立完善的养殖管理档案。